Condensed Matter) (Vol 19)

Definitions, units and conversion factors

Units are given for the cgs/emu system and SI, for defining relations of the magnetization, B = H + 4πM, B = µ0(H + M) and B = µ0H + M, respectively. µ0 = 4π⋅10–7 VsA–1m–1, A: molar mass, ρ : mass density. Quantity

cgs/emu

SI

B

G = (erg cm–3)1/2 1G≡ 1 Oe = (erg cm–3)1/2 1 Oe ≡ B = H + 4πM G 1G≡

T = Vs m–2 10–4 T A m–1 103/4π A m–1 B = µ0(H + M) A m–1 103 A m–1

B = µ0 H + M T 4π⋅10–4 T

P = MV G cm3 1 G cm3 ≡ σ = M/ρ G cm3 g–1 1 G cm3 g–1 ≡ σm = σA G cm3 mol–1 1 G cm3 mol–1 ≡

P = MV A m2 10–3 A m2 σ = M/ρ A m2 kg–1 1 A m2 kg–1 σm = σA A m2 mol–1 10–3 A m2 mol–1

P = MV Vsm 4π⋅10–10 V s m σ = M/ρ V s m kg –1 4π⋅10–7 V s m kg –1 σm = σA V s m mol–1 4π⋅10–10 V s m mol–1

χ

P = χH cm3 1 cm3 ≡

P = χH m3 4π⋅10–6 m3

P = χ µ0 H m3 4π⋅10–6 m3

χV

χV = χ/V cm3 cm–3 1 cm3 cm–3 ≡

χV = χ/V m3 m–3 4π m3 m–3

χV = χ/V m3 m–3 4π m3 m–3

χg

χg = χV/ρ cm3 g–1 1 cm3 g–1 ≡

χg = χV/ρ m3 kg–1 4π⋅10–3 m3 kg–1

χg = χV/ρ m3 kg–1 4π⋅10–3 m3 kg–1

χm

χm = χg A cm3 mol–1 1 cm3 mol–1 ≡

χm = χg A m3 mol–1 4π⋅10–6 m3 mol–1

χm = χg A m3 mol–1 4π⋅10–6 m3 mol–1

R0 , Rs

ρH = R0B + 4πRsMs Ω cm G–1 1 Ω cm G–1 ≡

ρ H = R 0 B + µ0 R s M s m3 C–1 100 m3 C–1

ρH = R0B + RsMs m3 C–1 100 m3 C–1

H M

P

σ σm

Ref. p. 1881

6.1 Amorphous 3d-M alloys (M = 4d, 5d, or main group element)

1

6 Liquid-quenched alloys 6.1 Liquid-quenched and sputtered alloys of 3d elements and main group elements 6.1.1 Introduction 6.1.1.1 General remarks Recently, the development of new solidification techniques has made available a variety of new materials with composition ranges unattainable in crystalline alloys. Amorphous metallic alloys can be obtained by rapid solidification from the liquid state. Typical cooling rates are of the order of, or higher than, IO6K/s. Existing and possible applications of amorphous magnetic materials are in context with their soft magnetic properties, sometimes in combination with high electrical resistivity, their production-inherent low thickness and magnetomechanical properties. Magnetic cores with low losses and specifically designed hysteresis loops, magnetic heads, magnetic sensors and other applications are developed and partly commercially used. For application-addressed magnetic properties see sect.7.1 in subvolume 111/19i. This data compilation will concentrate on the intrinsic magnetic properties of amorphous alloys, i.e., their susceptibility in the paramagnetic region, magnetic moments and saturation magnetization, phasediagrams and transition temperatures of ferromagnetically ordered alloys as well as of those alloys with more complicated magnetically ordered structures (e.g.amorphous spin glasses).Nonmagnetic properties are included if they are in some respect related to the magnetic properties, e.g. crystallization temperature, density. Out of scope are systemscontaining rare earth elements, e.g. transition metal (TM) - rare earth (R) alloys; they are dealt with in sect. 6.2, and also such alloys containing TM, R and other elements, cf. also [88 H 21. Data for amorphous alloys produced by methods other than the liquid-quenching or sputtering, e.g. electrodeposition, evaporation, ion implantation, solid-state reaction, spark erosion, etc.,are not included in this chapter. Further on, we do not deal with the diamagnetic properties of amorphous alloys, since the latter are closely related to superconductivity. For an introduction to the problems of amorphous magnetic alloys the following books and review articles are recommended: [80 H 1,83 L 1,84 M 7,84 K $84 E I,87 0 11.A survey with an extensive bibliographical part r is given in [83 F 2, 86 K 31.

6.1.1.2 Preparation methods Widely used techniques for the production of amorphous materials are: splat cooling and melt spinning [SSG 23. For research purposes small samples can be obtained by solidification of a liquid droplet in a pistonand-anvil or two-piston device. Melt spinning technique permits the formation of continuous ribbons (e.g.,by quenching the molten alloy on a rotating copper wheel or betweentwo rotating cylinders). The ribbons are one millimeter to several centimeters wide and 30. ..50 pm thick. Wider ribbons (up to 10.. .30 cm) can be produced by the planar-flow-casting method. Another method for the production of amorphous alloys is sputter deposition: the material of interest is bombarded at the cathode with positive ions of a rare gas. Thereby the atoms of the target are released and collected on a substrate at the anode. See [84 M 73 for a review, and also [88 W I]. The inclusion of sputtered thick amorphous samples, separated from the substrate or not, and, to some extent, of sputtered films was dictated by the similarity in the values of the magnetic parameters of both groups of amorphous alloys for the samechemical composition, together with the wider range of alloy composition which can be prepared in amorphous form by sputtering. As most of the data compiled concern liquid-quenched amorphous alloys, this is not specially indicated in the tables and figures, whereas the data for sputtered samples are identified as such.

Landolt-Bijmstein New Series III/l9h

Kobe, Ferchmin

2

6.1 Amorphous 3d-M alloys (M =4d, 5d, or main group element)

[Ref. p. 188

6.1.1.3 Structure It is hardly possible to specify the atomic structure of a noncrystalline solid as precisely asthat of a crystal. An amorphous alloy can be characterized by the absenceof long-range order or periodicity’in the microscopic structure. The range of the short-range order is about 10A (1 nm). The local order in the neighbourhood of a given atom may be noncrystalline (e.g.the local atomic arrangement of icosahedral symmetry) or that of a nearly crystalline equilibrium or nonequilibrium phase [87 0 1-J.To decide whether a substanceis amorphous or not, X-ray, electron and neutron diffraction can be used. In contrast to crystalline materials, the diffraction pattern consists of diffuse rings which sharpen as the materials transform, on heating, into polycrystalline phases (sometimesbeginning with a quasicrystalline phase).However, it is not possible to distinguish an amorphous structure from one that is crystalline on a scale of lessthan about 20 8, (2 nm) [84 M 7-J.An example of a reduced radial distribution function, which is related to the probability of finding an atom at somedistance from a given atom, is shown in Fig. 1 [82A 4, 84 E l] for Fe,,B,,.

600 nmm2

-300I 0.1

0.2

0.3

0.1

0.5

0.6

0.7 nm 0.8

r-

Fig. 1. Reduced radial distribution function 4rrr[e(r)e,-Jas a function of distance r from an averageorigin atom for Fe,,B,,. e(r): density of atomsat distancer, eo: averagedensity [82A4,84El].

Systems with structures other than amorphous, which can also be obtained by rapid solidification or sputtering, are not included in this data compilation. It concerns micro- and nanocrystalline materials and the recently observed “quasicrystals” (systemspossessingnoncrystalline short-range order and quasiperiodic longrange order) as well as mixed amorphous/crystalline systemsin caseswhere partial crystallinity has been found by the authors. The magnetic properties of powdered systemsgenerally differ from those of the ribbons and depend on the details of the process of powder preparation. Because of the resulting spread in magnetic properties they, too, are omitted. An amorphous alloy is in a thermodynamically metastable state. Such a state cannot be as uniquely defined as a crystalline stable state. There exists a multitude of possible amorphous structures with grossly different atomic arrangements and it is claimed that at least two different amorphous phasescan coexist 186Z 1,87 B 5-j. The consequencesof metastability for the presentation of data on magnetic and other properties are twofold: (i) Firstly, liquid-quenched alloy samples of the same composition from different batches can presumably have somewhat different thermal histories (in the caseof amorphous alloys, mostly a different quenching rate) leading. similarly to the situation in ordering or segregating crystalline alloys (cf. 171V 11, chapter 21, 5), to different local configurations of magnetic atoms, in particular different numbers of magnetic neighbours of magnetic atoms. A practical rule states that the magnetization data of liquid-quenched alloys of the same

Kobe, Ferchmin

LandolbB6mstein New Series IW19h

Ref. p. 1881

6.1 Amorphous 3d-M alloys (M = 4d, 5d, or main group element)

3

composition usually differ by no more than several percent. Whenever possible, a typical value is given together with the upper and lower limit data. Quite different metastable statescan be obtained by imposing well defined external conditions during the quenching process,e.g.by applying strong external magnetic fields (see[87 E I]). Such conditions are indicated by remarks. (ii) On the other hand, a metastable state tends to transform continuously towards progressively more stable states.This process is driven by the annealing temperature and time, sometimesalso by a magnetic field and is accompanied by structural relaxation phenomena. Data on magnetic properties measured after structural relaxation are given together with the annealing conditions. Starting from the as-preparedstate the relaxation by annealing leads mostly to a relief of stress induced during the preparation process. For commercial amorphous alloys nominal compositions only are usually available. For a few other alloys solely nominal compositions are available as well. Such cases,representing an obvious source of uncertainty, are indicated in the “remark” column and should serve for provisional orientation. Another source of uncertainty in magnetic data stemsfrom the nonuniformity of the samples:as a rule, due to the conditions of preparation, a surface layer differs chemically and structurally from the bulk and the surfaces can differ from each other as well [87 S 51.

6.1.1.4 How to find the data of a specific alloy in this chapter? As a consequenceof the preparation conditions there are more amorphous alloys than crystalline materials with the same components. The following rules should help the reader to find a specific alloy. In principle, the rules of order for the amorphous materials follow the system of Chemical Abstracts (CAS). Becausethe alloys under consideration are transition-metal-based, these elements determine the ordering. (i) First, all alloys with a single TM element are listed following their order in the respective row of the Periodic Table (Ti, V, Cr, Mn, Fe, Co, Ni, Cu). The other elements are arranged with decreasing atomic percentage (e.g. Fe,,Si,5B,,). (ii) Next, for a given TM element (e.g.Fe) the alloys are ordered alphabetically according to the first (i.e. the most abundant) non-TM element (e.g.FeB, FeC, FeSi, . . .). Alloys composed of the sameelements are arranged with increasing TM content (e.g.Fe7aBz1,Fe,,B,,, . . .). If the composition range of an alloy has to be given, the right place is before the alloy with the lowest TM concentration (e.g.Fe,,, - XB, (17 5 x 5 21), Fe,aBzl, . . .); less precise formulae are placed before more precise ones. (iii) Alloys with more than one non-TM element are arranged in alphabetical order immediately after the alloys with only one non-TM element and so on (e.g. Fe,,B,,, Fe,,B,,Mo,, Fe,,B,,Mo,, Fe,,B,,Mo,, . . .). Please note that entries are not given, so that e.g. FMWbSi5, WA7Nb5, %3bW@L Fe,,B&3,, can be found only after the Fe-B alloys, whereas Fe,,Si,,B,, only after Fe-Si. Sometimesa given composition range covers two formulae (e.g. Fe,,B,S-.$3i, with 12sx5 14 covers Fe,,B,,Si,, and Fe,,Si,,B,,). The formula is then situated only at the first place in the materials table (in the above example, before Fe,,B,,Si,,). (iv) In a formula for alloys with two TM elements,in general, the TM element with the higher atomic number in the Periodic Table is inserted preceding the TM element with the lower number. In this connection we consider Cu as a TM element. However, becauseit is usual in the literature to write e.g. Fe-Ni instead of Ni-Fe (and Co-Ni instead of Ni-Co), we keep the place an alloy should have in the table according to the above rules, but once the place is chosen, we write the alloy formula in priority order: Co, Fe, Ni, Cu. The ordering rule is illustrated by the following example for some Ni-Mn and Ni-Fe alloys: Ni,,Mn,Zr,,, Fe,,Ni,,B,,, Fe,,Ni,B,,. (v) For alloys with three TM elements first the ordering principles for the respective alloys with two TM elements are used and then the third TM element is added according to the Periodic Table order. (vi) With respectto the non-TM element in a given alloy, the materials are inserted in the order of increasing content of the sum of all TM elements.If this sum is equal for alloys with the sameelements,the alloy with the lower content of the first-written TM element is given first. Examples for these rules are to be found in the list of materials (subsect.6.1.2). The reader is advised to start his search with the materials list for the following reasons: the information he needscan be included either in a table or in a figure. Moreover, it occurs that more than one alloy is contained in one figure. Then the figure is placed according to the material which occurs first according to the foregoing rules.

Land&-Biirnstein New Series III/19h

Kobe, Ferchmin

6.1.2 Materials and properties - guide Composition range

Properties

Figures

Cr-Ge CflOO-,Gex

Tables

22 22 8 9

Mn-B M%,B,,

2 22 10

15x57

ti

CrPdGe

-

XPdGe)-

’

22

Mn5A8

4

10

vs. T Mn-P-C MwP&o

2 22 11

Mn-Pd-Ge Mn,Pd,,-,Ge,,

15x57

ti

12

MnPdGc -

XPdGe)

- ’

vs. T Mn alloys

Mn20Ah

Figures

Mn-Al-Si Mn, 7A158Si25 Mn-Au-!3 Mn,Au,,Si,,

Cr-PdSi Cr,Pd,$i,, Cr,Pd,,Si,, Cr,Pd,,Si,, Cr.,Pd,,Si,, CrsPd,,Si,, Cr,Pd,,Si,, Cr,Pd,,Si,,

Mn-Al MnxA400-, MnlsA185

Properties

Mn 22.~4177~ Mn 24.JA17S.7

Cr alloys

Crd+e72 Crdk4 Crdh %8Ges2 Crs7Geb3 Cr-Pd-Ge CrxPd82-xGe18

Composition range

Tables

15~x524

@(x) x&9 x.c T vs. T L,(T) (log scale) x'. 09 CgrPerr xac(T) (log scale) C8

7 5 6 6

2 2

Mn-Pd-Si Mn,Pd,,Si,, Mn,Pd,,Si,, Mn,Pd,,Si,, Mn,Pd,,Si,, M&i Mn~oo-xS4

2 2 2 2

0 0 0 0 255x575

TW' ~(Tm4.2 vs. x

69 w

Land&Biimstein New Series IIIIl9h

Kobe, Ferchmin

Composition range

Properties

Figures Tables

Fe-B (continued)

Fea4B16

Fe85.4 B 14.6

D

12

critical exponents

20

4, as Tc Tc 4 To TX Tc(hAT&-a) 4 To TX

21 22 22 21 22

129 83

21 22 12 21 22 21 22 21 22 21 22 21 22

D 4, a, TC 4

Fe,.&,

F%.,B,,.a

TC

Fea7B13

4,~s To TX 4, Tc

Fe81.5 B 12.5 %A2

F’Fe Tc

Fe-B-Al Fe84B16-xAlx Fe84B,3A13 Fe-B-AI-Si

05x53

o,, T,, TX vs. x Tc

84 22 21

Fe,,B,,A16Si2 Fe-B-Au Fe80-xB20Aux Fe82-xB18Aux

b6B20Au4 Fed, ,Au2

O~xB fitting a power law ca(T,-v thermogravimetry thermogravimetry

82F3 82F3 85Cl 8527 8527 82Cl 82Cl 81L3

K

.

with /?=1/2...1/3 with /?=1/2+..1/3

1.2 Pa I 0.8 Id az

0

xFig.210. Fe,OO-,Ti,. Magnetic moment per atom, p,,, of sputteredsamplesas a function of Ti concentration, x. T=4.2 K [8SS9].

20

40

x-

60

80

100

Fig. 211. FelO,,-xTir. Curie temperature, Tc, estimated from Arrott plots and paramagnetic Curie temperature,0, of = 50 urn thick sputteredsamplesas a function ofTi concentration,x [88S9].

Kobe, Ferchmin

Land&-BCmstein New Series 111/19h

I””

137

6.1.6 Amorphous Fe-Ti-M

Ref. p. 1881

1

f

FelooMx Ti,

‘

T= 4.2K

1 75 50

00

k?

0 25 0 0 0

IO

20

x-

30

n 40

50

0

20

60

80

100

x-

Fig. 212. Ferc,,-,Ti,. Saturation magnetization, es, at 4.2 K of sputtered samples as a function of Ti concentration, x [8336].

Fig.213.

Fe,TiIO,,-,,

I

60

Co,,,.xFe,Ti,,,

Fe,Ni,,-,Ti,,,

Fe,Cu,,.,Ti,,. Fe atomic magnetic moment, pFe, from magnetic hypertine field measurements at 4.2 K as a function of Fe concentration, x. Several-pm-thick samples obtained by high-rate sputtering. The magnetic moments of Co, Ni, and Cu are assumed to be 1.17, 0.17, and 0 pa, respectively [87L4].

500,

I

I

I

60

80

I I-u

d 40

20

-0 Fig.214.

40

Fe,Tir,,,,-,,

40

60

x-

Co,,-,-,Fe,Ti,,,

80

100

Fe,Ni,,-,Ti,,,

Fe,Cu,O~,Ti,O.Spontaneous magnetization, (T,, at 6 K of several-pm-thick samples prepared by high-rate magnetron stuttering as a function of Fe concentration, x [87L4]. -

Land&-BBmstein New Series III119h

0

20

40

IO0

x-

Fig.215. Fe,TiiOO.,, Fe,TM,O.xTi,, with TM= Co, Ni, Cu. Curie temperature, rc, vs. Fe concentration for thick high-rate magnetron sputtered samples [84L3, 87L43.

Kobe, Fercbmin

6.1.6 Amorphous Fe-Ti-M

0

2

4

6

8

10 kbor 12

0 Ti

[Ref. p. 188

V

Cr

Mn

Fe

Co

Ni

cu

PFig.216. Fe,sTi,s, Fe,,Ti,,. Shift in the Curie temperature, AT,, as a function of pressure, p, for highrate sputtered samples (~0.3 mm thick). Fe,sTi,, (Tc=238 K),Fe,,TiZ,(Tc=240K)[82F3].

Fig.217. Fe,,TM,B,,, TM =Ti, V, Cr, Mn, Fe, Co, Ni, Cu. Average magnetic moment per Fe atom, jFe. for Fe-B alloys substituted with various TM elements [8262].

--

9

m2 G

200 &F kg 180

1.50

I 100 d

I 160 t3”

120 li

I V

Cr

Mn

Fe

Co

Ni

Cu

0

150

300

450

600

K 750

T-

Fig.218. FesoTMJB,,, TM=Ti, V, Cr, Mn, Fe, Co, Ni, Cu. Room-temperature saturation magnetization, a,, for Fe-B alloys substituted with various TM elements. Melt temperature before quenching: 1520 K [81L3].

Fig.219. (Fe,.,Ti,),,B,,. Saturation a,, versus temperature, T[82Cl].

Kobe, Ferchmin

magnetization,

Land&-BGmstein New Series 111119h

6.1.6 Amorphous Fe-V-M

Ref. p. 1881

139

6.1.6.5 Fe-V alloys Table 29. Fe-V alloys. Atomic magnetic moment at low temperature, unless stated otherwise, and saturation magnetization. Remarks

>m’/kg

T K

137 160 181 186 170

4.2 300 RT 0 0 0 0 0

Ref.

PTM

p(Fe), p(V) = - 0.6 uB assumed PTM

extrapolated from 77 K Es,.

165 137 186

77 293 0

extrapolated from 77 K

2.02

PFe

182 156 185

77 293 0

extrapolated from 77 K

1.99

PFe

182 163 108 123 136 133

Fe,,V,,B,,Si, +O.Ol at% N Fe,,V,,B,,S& +O.Ol at% N Fe,,V,B,,Si, +O.Ol at% N Fe77Vd’t&,

Table 30. Fe-V alloys. Curie temperature, T,, and crystallization temperature, Tp TX T, K K FemVdm Fe7~V5Jh Fe76V4JWi5 Fe,,V,B,$i, Fe7gVlB15Si5

Remarks

Ref.

500 81L3 763 537 87P2 495 M(T), estimated 81 565 M(T), estimated 81 H H44 690 M(T), estimated 81 H 4

77 293 0 0 0 RT

I2.E lJ4

o TM=Fe-V A Fe-Cr v Fe-Mn o Co-Fe x Fe -Ni . co-v . Co-Cr . Co-Mn

l”80

2.0l-

I I5 I
Tc) are (I) 104.1 (111.3)K; (2) 102.4 (109.8)K; (3) 101.0 (108.4)K; (4) 99.7 (106.8) K; (5) 98.5 (105.4) K. It is found that standard critical behaviour is induced in this random magnetic anisotropy (RMA) system by application of a large enough magnetic field. At low fields the system shows nonlinear critical behaviour (cf. Fig.244 and Table 25) [87L 11.

Sostarich

Land&BBmsfein Nea Series III119h

275

6.2.4 Amorphous R-3d (R = Ce, Pr, Nd, Sm)

Ref. p. 3421

6.2.4 Alloys with light rare ‘earth elements (Ce, Pr, Nd, Sm) 6.i.4.1 Magnetization, magnetic moments, ordering temperatures and type of magnetic order

/-

1!il b-7-4 1=20K ,,/-0’

1 ’

. /” /’

100

-

,,

l

,,:’

.

b

/’ ,A 50

l

01 o 501 40

0

.p,,H=O . 9.5T

/

60

70 x-

80

90

40

100

Fig. 118. Prl,,O-xFeX. Spontaneous specific magnetization b,r and specific magnetization at poH=9.5 T of melt-spun alloys at 20 K vs. Fe concentration. 4sp was obtained by extrapolating the high-field magnetization data linearly to zero field. The dashed lines included with the data represent calculated values based on (I) a ferromagnetic alignment between ordered Pr and Fe sublattices (Prt Fe?) and (2) a sperimagnetic alignment assuming completely disordered Pr with ferromagnetically ordered Fe sublattices (Pr(0) Fe?). The calculations are based on a free-ion moment value for Pr (3.58 p*(B)and a composition-dependent Fe moment ranging from 2.04 ur, to 1.45 pB for the PrzFe,, (x=89.5) and PrFez (x 2: 66.7) compositions, respectively [81 C 31.

50

60

80

90

100

Fig. 119. NdlcemxFex. Spontaneous specific magnetization a,, and specific magnetization at ~~H=9.5 T and 20 K vs. Fe concentration. Q, was determined by extrapolating the high-field magnetization data linearly to zero field. The curve represents the calculated magnetization for the modified sperimagnetic structure proposed by Taylor et al. [78 T I] in which the Fe and Nd moments are distributed on cones of half anglez45” and 120”, respectively (cf. Fig.120). The calculation implies a composition-dependent Fe moment, ranging from 2.04 ltB to 1.45 pr, for x -89.5 and 66.7, respectively, and a Nd moment of 2.7 pr, [81 C 11.Cf. also [81 C2].

b

a

Fig. 120. Nd-Fe. Schematical representation of (a) classical sperimagnetic structure and (b) the sperimagnetic structure proposed for amorphous Nd-Fe alloys in [78 T I]. For the classical sperimagnet in a weak applied magnetic field the transition metal magnetic moments are ferromagnetically aligned, whereas the rare-earth magnetic moments are distributed in a hemisphere with the polar direction parallel to the field. In the structure shown in (b) the Fe and Nd moments are distributed on cones of half angle r~45” and 120”, respectively [81 C I]. Land&Biimstein New Series III/19h

70 x-

Sostarich

2.5 %LL\Q Ii I

I 22

7n -.-

[Ref. p. 342

6.2.4 Amorphous R-3d (R=Ce, Pr, Nd, Sm)

276

-x I

I

I

b

1,

I390

i I I t

/

‘9 1.5 I$

0

’

, I..!?

“330

1.0III300

0 0

10

20

30 Nd-

40

50 al% 60

I

Fig. 121. NdlOO-xFel. Composition dependence of several magnetic quantities in melt-spun alloys [87S2]. Average magnetic moment per atom, p,,, obtained from the high-field magnetization value at 4.2 K and p,,H= 15 T. The magnetization was measured by a vibrating-sample magnetometer installed at a highpower Bitter coil. Even the field of poH= 15 T is not sufficient to saturate the magnetization at 4.2 K. Average Nd magnetic moment p(Nd) calculated from j,, assuming a constant Fe moment j(Fe) = 2.0 pe, as suggested by the constant hyperfine field. Average 57Fe hypertinc ticld B,,, at 77 K, cf. also Fig. 162. Curie temperature Tc obtained from low-field magnetization measurements with a magnetic balance (cf. also Figs. 126 and 128).

I

RIOO-xCox 4 % I 22 3.

\t

Pe

I

R = Nd I .

I

u

14

I

3 3

‘. ‘P

t =

Pr

I

2 14"

19"

t-i

I

i

2a

5 P

\T

31b 40

50

60 R-

70 of%

I 80

Fig.122. Rloo.,Co, (R=Pr, Nd). (a) Effective magnetic moment per average atom, jell, and (b) average effective moment per rare earth atom, perr,R,vs. rare earth concentration. The jcn values are obtained by fitting the xi r vs. T data to the Curie-Weiss law (cf. Fig. 136). jerf.R was determined from the equation 100&=(100-x) j$r,R. Thcj,,, value for the Nd6.+Cojg alloy marked by a full circle is that given in [78G 11.The broken lines in (b) mark the effective moments of the free tripositive Nd3+ and Pr3+ ions, respectively [87Y 11.

Sostarich

Landolt-Biimstein New Series 111,‘19h

Ref. p. 3421

6.2.4 Amorphous

277

R-3d (R = Ce, Pr, Nd, Sm)

I SmlOdex 120

I 80

b

0 0

20

40

60

80 at% 100

Sm-

Fig. 123. Sml,,O-XFe,. Specific magnetization u of melt-spun alloys at 77 K and in a magnetic field of koH= 1.5 T as function of Sm concentration. The magnetization was measured using a vibrating-sample magnetometer [86 M I].

x-

Sm -

Fig. 124. SmiOO~XCoX.(a) Effective magnetic moment per average atom, Fern and (b) average effective moment vs. Sm concentratton. The perf per Sm atom, Aff,k values were obtained from experimental data at Tc (cf. also Fig. 142) and the corresponding peff,smwere calculated from the equation loo~~~f=(loo-x) j~z~r,s,,,. The broken line in (b) marks the theoretical effective Bohr magneton number of 0.84 for the free Sm3+ ion [87Y I].

Land&-Bknstein New Series III/19h

Fig. 125. PrIoO.,Fe,. Curie temperature Tc of meltspun alloys as a function of Fe concentration. The Curie temperatures were obtained from a2 vs. H/a plots (Arrott plots) [81 C 31.

Sostarich

[Ref. p. 342

6.2.4 Amorphous R-3d (R=Ce, Pr, Nd, Sm)

278

600 K

Nd 1oo-x Fe, d-o 7

Olll

30

40

60

50

70

80

2001 0

0 91

I 20

x-

I 60

I 40

I I 80 ot% 100

Sm-

Fig. 126. Nd,,,,,-,Fe,. Curie temperature Tc vs. Fe concentration. Open circles - data for melt-spun alloys determined from Arrott plots. For the sake of comparison data for a series of evaporated Nd-Fe films from Ref. [78Tl] are included (solid circles). It is suggested that the discrepancy between the two sets of data at lower Fe content could imply that melt-spun alloys are less amorphous than their evaporated counterparts

Curie temperature Tc of meltFig. 127. Sm,,,-,Fe,. spun alloys vs. Sm concentration. T, values were determined from 6’ vs. Tplots [86M 11.Cf. also Fig. 128.

[81Cl].

160 K 120

I 80

8

200 0

20

40

60

0 50

80 ot% 100

50

60

70 ot%

80

R-

RFig. 128. R,OO-xFer(R=Pr, Nd, Sm). Curie temperature Tc as function of rare earth content for amorphous melt-spun alloys (closed symbols) and intermetallic compounds (open symbols). The ordering temperatures of the amorphous alloys were determined from a2 vs. T plots [86M 11, whereas those of the crystalline compounds were taken from [79 K 11.

Fig. 129. RIO,&ox (R=Pr, Nd, Sm). Ferromagnetic Curie temperature Tc (open symbols) and paramagnetic Curie temperature 0 (closed symbols) vs. rare earth concentration for three melt-quenched alloy series [87Y 11. (I) and (2) in the case of SmrOJox are Tc data of [80B2] and [83A 31, respectively. The T, values of NdlaO-$ox indicated by (3) and (4) are from [78 G l] and [85 W 31,respectively. Cf. also Table 15 and [88 Y 21.

Sostarich

Landolf-BCimstein New Series III/19h

Table 15. Magnetic moments, ordering temperatures and magnetization data of liquid-quenched R-TM alloys with R = Pr, Nd, Sm, and TM = Fe, Co, Ni. The type of magnetic order is given only where it is explicitly mentioned in the reference. peff,R

“1

PB

3.6“) z3.379

PR =I

0

T,,

PB

K

K

Am2 kg-’

cf. Fig. 125 cf. Fig. 125

40 166

1.34”) 1.91b) Lo=) x l.Ob)

2 ~6~)

Fig. 12.I 2.4 “) 3.75‘)

3.59

1.4(1)9 ‘) “) ‘) “) ‘) ‘) 3 “) ‘) j) k,

35(3)“)

1.33 1.1”) 1.51”)

T,

15(5)“1 >400 llO(l)d)

CT

353 11 48Oh) 330’) 31(2)‘) 45 “) 31.7’) 38(2)“) 38(2)‘) 92(5)‘) 90(5)‘) 18(5)k, >300 >400 60 “) 57.8‘) llO’), 114”) (T,=55K)

Fig. 119

Magnetic order

Ref.

Remarks

speri “) speri “) ? SG-like spero speri

8OC2 8OC2 80B3 84C2 82C4 81 Cl, 82C5 8782 85W3 80B2 82B2 78Gl 85W3 85W3 85W3 80B3 81Bl 83S2 80B2 82B2 82A2,83A3

d value at 20 K d value at 20 K

Fig. 137 SpXi

Fig. 140 32

? speri 3 speri “)

“)

xacpeakat T,

magnetic structure in Fig. 120

cf. Fig. 203 cf. Fig. 149 cf. Fig. 149 B,,,(Fe) = 30 T at 4.2 K ts, value at 4.2K weak x,c maximum Tf = T,: temperature of magnetization maximum

/ The effective magnetic moment j!eff,Rand the magnetic moment pR,given above are averages per rare earth atom. Calculated from the value of c given in column six. Sperimagnetic structure in which the Pr magnetic moments are random and the Fe magnetic moments are ferromagnetically aligned. Derived from Curie-Weiss plots (x-l vs. 7’). Calculated from magnetization value at 4.2 K in a field of p&Z = 1.8T. Noncollinear arrangement of R magnetic moments; p(Ni) E 0. ‘) Calculated from the value of the effective moment per average atom c,,, at 4.2K determined by fits to the law of approach to saturation. given in the reference. Obtained from Arrott plots (a2 vs. H/a). “) Obtained from the temperature dependence of the coercive field H,. Determined from the temperature dependence of low-field magnetization. “) After [86M I]. Determined from xac vs. T plots. P) Ferromagnetic interaction between Sm atoms for Tf < T< T, and Obtained from low-field o2 vs. T plots. spin-glass-like state for T < Tf. It is assumed that p(Co) r 0.

Table 16. Liquid-quenched ternary alloys with light rare earth elements, 3d transition metals, and B or Ga as glass formers. Average Fe magnetic moment, magnetic ordering temperatures and specific magnetization. The type of magnetic order is given only where it is explicitly mentioned in the reference. tl Am2kg-’

Magnetic order

Ref.

9.5 b) 21 b)

spero spero

13b) Sd), 375d)

spero

82C4,82R I 82C4 84C2 82C4,82RI 82C3

07 I.67 ‘) I.97 ‘) gI.60’) z2C)

Fig. 145

SG-like (at 4.2K)

21Sf) I.69 ‘)

(Pro.BoGao.2d&% ‘1 ro.dh 20)40Fe60 ‘) ~~ro.BoGao:20~20Fe.o 9

475 h) lob) 460 h, 455 h) 783, 1053

22.5 “) 22.7 “) 75.15 “) 153.22“) 50.5 ‘) 93.5 ‘)

414’) 413’) 418 ‘) 142”) 171.5‘) 9.5 b) 13b) 6.2 b, gb) cf. Fig. 152 24 b, 455 ‘) 4W) “1 436 ‘)

spero spero spero

149(10)3

84C2 8IC4 82C4 84C2 82HI,84HI 82C4 82H1,84Hl 82HI,84Hl 82HI,84HI

12b)

speri “)

Remarks

82K2

The two Curie temperatures indicate the presence of two magnetic phases in the alloy. a, values (cf. Fig. 130)

87A2 84H2 86A2 82K2

a, values (cf. Fig. 130)

82RI 82C4 82C4 82C4 84C2 82RI 87A2 88CI 86192

Table 16 (continued).

d Am2 kg-’ z 2.0 ‘) 1.58‘) 1.60“) 1.25“) 1.16”) 0.89 “)

W,.,,Co,.&mJ%o SmFe,B Sml 5Fe77Bs SmFeCo,B SmCo,B

460 “) 558“) 531”) 469 “) 427 “) 370“) 27 “) 38”) 457 3 479 “) x 673“) 503‘)

Magnetic order

182p) 17OP) 139P) l16p) 114P)

ferro ferro ferro ferro ferro spero

481

speri

Ref. 88Cl 88A2 88A2 88A2 88A2 88A2 82Rl 85H2 87A2 86A2 87A2 87A2

Remarks

j!(Fe) “) = 1.97pB p(Fe)“)= 1.89pB p(Fe)“)=1.49prr jj(Fe)“)=1.12pB j$Fe)“) = 1.05pB sharp speromagnetic transition (cf. Fig. 215) cf. Fig. 153

3 Calculated from the average 57Fe hyperhne field Bhypby the formula jj(Fe)/pB=B,,p/15 T. “) Temperature of peak in the xacvs. T dependence. ‘) At 300K. “) DC susceptibility peak temperature. ‘) At 4.2K. ‘) a,, at 4.2K obtained by extrapolating the high-field part of the magnetization isotherm to H =O. 3 Room-temperature value in a field of p,H =2T. “) From c vs. T measurement. A low-temperature x,, peak at about 8 K is also reported and interpreted as an indication of the presence of two amorphous phases, a PrGa-rich one (T,r 8 K) and a PrFe-rich phase ordering magnetically below about 470 K (cf. Fig. 151). j) Partially crystalline sample. ‘) From c vs. T dependence. ‘) At 0 K (extrapolated). “) Determined with a differential scanning calorimeter. “) The Nd magnetic moments (3.27uB)are distributed over a cone of half angle x 60”, whereas the magnetic moments of the Fe sublattice are assumed to be collinear. P) o, value at 4.2 K (measured on saturated sample). 3 a, at 4.2K from the law of approach to saturation. “) Calculated from c, values in column four, assuming a constant Nd magnetic moment of 3.4 pa. t, A general property of these alloys seemsto be the segregation into Fe-rich and Fe-deficient regions having different magnetic transition temperatures.

282

[Ref. p. 342

6.2.4 Amorphous R-3d (R=Ce, Pr, Nd, Sm)

175

160p_ . .

Am? -G 150 I 125

,

,

I

I

6

7

120

t?

b"

100

10

15 Pr-

20

25 ot% 30

Fig. 130. Pr,,,JPeO,sBO,,),. Specific saturation magnetization 6, of melt-spun alloys as a function of Pr content The magnetization was measured at room temperature and at 4.2 K using a vibrating-sample magnetometer [82K 21.

100

60 0

12

3

4

5

Fig. 131. R,Fesov,BZo (R=Ce, Nd, Sm, Gd). Specific saturation magnetization a, as function of rare earth concentration for melt-spun alloys at room temperature [88Gl].

700 "C 600

200 Am2 kg 190

I 500 I-Y 400

180 I 6 170

300 200l150 0

Fig.132. Nd,Fe,,B,,-,. Curie temperature Tc of melt-quenched alloys as a function of Nd content [87M2].

160

12

3

6

5

6

xFig. 133. Sm,Fes,,-,Bzo. Curie temperature 2-c and specific saturation magnetization fl%at room temperature as functions of Sm content in melt-spun alloys with 0 5 x 5 6. The Curie temperatures were determined from a, vs. Tcurves [88 IS].

Sostarich

Land&-BBmstein New Series III119h

283

6.2.4 Amorphous R-3d (R=Ce, Pr, Nd, Sm)

Ref. p. 3421

6.2.4.2 Temperature dependenceof magnetization and susceptibility

175 & kg 150

125

bI IN

75

5[

2:

1

100

200

300

400

500 K 600

Fig. 134. Pr,,,,,-,Fe,. Specific magnetization 0 vs. temperature for melt-spun alloys with the Fe concentration given as parameter. The magnetization was measured in a field of p,H=1.6 T on finely powdered specimens. The anomalous increase in the magnetization of the Pr,,Fe,, alloy at low temperatures is interpreted as due to the presence of a small amount of crystalline Pr [81 C3].

2!

100

200

300

/-I

400

500 K 600

Fig. 135. Ndl,,O-nFex. Specific magnetization (I vs. temperature for several melt-spun alloys. The data were taken in a field of pLoH= 1.6 T applied prior to cooling the samples. The slight increase in the magnetization of the Nd-rich alloys (40 5 x 5 60) at low temperatures is interpreted as possibly indicating the presence of a second component (amorphous or crystalline) with a lower magnetic ordering temperature [81 C 11. Land&-B6mstein New Series 111/19h

’

Sostarich

284

Am? kg 40 k

6.2.4 Amorphous R-3d (R= Ce, Pr, Nd, Sm)

4 Fig.136. R 100-rC~x (R=Pr, Nd). Specific magnetization Q in a field p,,H= 1.4T and inverse magnetic susceptibility xc’ as functions of temperature for several melt-quenched alloys. The measurements were made using a Faraday-type magnetic balance and the samples were cooled to 4.2 K in zero field prior to the measurements. The ferromagnetic Curie temperatures Tc determined from Arrott-plots, are indicated by solid arrows, whereas the open arrows indicate the paramagnetic Curie temperatures 0 obtained by fitting susceptibility data to the Curie-Weiss law [87Y 11.

phl-xCox poH=l.CT

1,

20

I 10

2 10' 'cn 5kg

b

0

0 10

1 I 'ixDa 0

0 10

[Ref. p. 342

80 & kg I 60

1

b LO 0

0

10

1

0

0 0 Ndloo-xcox

50

100

150 l-

200

250 K 300

Fig. 137. Nd,&oJ1. Specific magnetization d of a melt-spun alloy as a function of temperature. The magnetization was measured by an adaption of the Faraday method. The solid curve is for heating in an applied field of poHa=0.9 T. The broken line was obtained after cooling the sample in the presence of the magnetic field [80 B 21.Cf. also Fig. 136.

x-60

I

20

25 43G "i3J m3

20

b lo

6 0

15 I

0

x"10 10

0 0 0

0 20

0 50

100

150 l-

200

40

60

80

K

l-

250 K 300

Fig. 138. Nd,,Co,,. DC magnetic susceptibility xs measured with a Faraday balance as function of temperature. The temperature of the susceptibility peak, 38 K, is taken to be the magnetic ordering temperature [78Gl].

Sostarich

Land&BBmstein New Series 111/19h

Ref. p. 3421

285

6.2.4 Amorphous R-3d (R=Ce, Pr, Nd, Sm) 140 &9 kg 120

I40 w kg

80

80 60

80

80 60 20 I

I

b

b " 60 40

20 40

40

-Am2 kg

20

30 I

20 0 20 0

50

100

150 T-

200

0 250 K 300

Fig. 140. R,,Fe,,, with R= Sm and Lu. Specific magnetization (Tof melt-spun alloys vs. temperature. The magnetization was measured during heating in an applied field of poHa= 1.8 T by means of an adaption of the Faraday method [81 B I].

Land&-Biimstein New Series III/19h

20 0 0

Fig. 139. Sm,,,-, Fe,. Specific magnetization D as function of temperature for several melt-spun alloys. The magnetization was measured in a field of l,,H = 1.4 T using a magnetic balance (Faraday method) in the temperature range from 4.2 to 300 K and a vibratingsample magnetometer above room temperature. The open and solid circles represent the data taken on heating the samples after cooling them to 4.2 K from room temperature in p,,H= 0 and 1.4 T fields, respectively. The downward solid arrows indicate the Curie temperatures Tc obtained from cr* vs. T plots. The upward arrows indicate the temperatures Tb around which shoulders exist in the xac vs. T curves (cf. Fig. 150). Field-cooling effects are observed at temperatures below T, (open downward arrows), and it is suggested that an unfreezing process of Sm-rich spin-glass clusters occurs between Tk and Tr on heating the samples [88 Y 31.

Sostarich

286

6.2.4 Amorphous R-3d (R = Ce, Pr, Nd, Sm)

[Ref. p. 342

4 Fig. 141. R,,,CO~~ (R= Sm, Nd). Specific magnetization Q as function of the applied magnetic field H, at various temperatures. The magnetization isotherms were measured on zero-field cooled samples using a Faradaytype magnetic balance. The amorphous alloys were produced in ribbon form by rapidly quenching from the melt [87Y I].

--A---+43 -

53

-

63

-

68 ^-

71

8 lO’/ln kg/m3 3 8

T=4.2K

15 25

2

35

0

39

0 2

I 8 y&C

46

0

0

49

2

43

T-

76

- - - 106

ol-----z-r-ot. . ..r OlPZ 01 -_--

.f

Z”

- - -157 f - : 215

--

I

1

I

0

0.3

0.6

- -293K I

0.9 PO”,-

t

l.2

I

1.5 1

,1.8

Fig. 142. Sm 100-xCo,. Specific magnetization d in a field of poH= 1.4 T and inverse magnetic susceptibility x; 1as functions of temperature for several melt-quenched alloys. The measurements were performed on heating the samples using a Faraday-type magnetic balance. Open circles: zero-field-cooled; solid circles: field-cooled. The broken lines represent the theoretical temperature dependence of the inverse magnetic susceptibility calculated using Van Vleck’s theory. The downward arrows indicate the Curie temperatures Tc determined from Arrott plots, whereas the upward arrows indicate the temperatures T, of transition from a mictomagnetic (spin-glass-like) to the ferromagnetic state [87Y 1,88Y3].

Sostarich

Landok-BBmstein New Series 111119h

Ref. p. 3421

6.2.4 Amorphous R-3d (R= Ce, Pr, Nd, Sm)

40 .4& 107 m3 G

I

287

40 106 4% kg i?

I

pr80 Ga20

I 207s

I 20 -2 10

0 70

85

100

115 T-

130

0 145 K 160

0

Fig. 143. Sm,,Co,, (Sm,Co,). Specific magnetization e and inverse magnetic susceptibility xi 1vs. temperature. The measurement was performed by magnetic translation balance in a magnetic field p,,H=0.7 T [83A3].

Land&-Biimstein New Series IIU19h

I_ 100

150 T-

1 . 250 K :

200

Fig. 144. Pr,,Ga,,. Magnetic susceptibility xE as well as inverse susceptibility xi1 as functions of temperature for a rapidly quenched alloy [84 C 21.

0

Ftg. 145. (Pr,,,,Ga,,&s,,Fe,,,. Spontaneous specific magnetization uspof a splat-cooled alloy vs. temperature. The Q,~ values were obtained by linearly extrapolating the high-field portions of the magnetization isotherms to H= 0. The dashed line represents the contribution of the magnetic Fe atoms to the reversible magnetization, estimated from 57Fe Miissbauer effect measurements to be 13.8 and 11 Amz/kg at 4.2 and 300 K, respectively [84C2] (cf. also [82 C 31).

50

50

100

150 T-

200

250 K

O

Fig. 146. Magnetic suscep(Pr,.,,Ga,.,,),,Fe,,. tibility xs vs. temperature. Susceptibility data were taken with a Faraday balance system in a field of poH= 70 mT as the sample temperature was raised. Open circles are values obtained after cooling in the field of 70 mT, whereas the solid circles are data taken after cooling in zero field [81 C4]. Cf. Fig. 144.

Sostarich

[Ref. p. 342

6.2.4 Amorphous R-3d (R=Ce, Pr, Nd, Sm)

288

150 w kg

125 100 I b

I5

25

0

200

kO0

600

K

0

800

100

200

l-

Fig.147. Nd,Fe,,B,. Specific magnetization u as function of temperature. u was measured by means of an adaption of the Faraday method in an applied field of lo6 Am-‘. (I) Amorphousmelt-spun sample. (2)CrystaL line sample [86B 11.

I 0

I 50

I 100 l-

I 150

K

300 l-

400

500

600 K 700

Specific magnetization u as Fig. 148. NdFe,,B,. function of temperature. tr was measured by an adaption oftheFaradaymethodinanappliedfieldof 1440 kAm-‘. (I) Amorphous melt-spun sample. (2) Crystalline sample. Curve (2) was obtained after correction for the presence of second phases [86 B 11.

I I-

21

1

II

I

I

II

0 O

20

60

60

I

I

K

80

l-

AC susceptibility Fig. 149. Nd,,Co,, and Nd,,Co,,. x,~ vs. temperature. Peak temperatures taken to be the magnetic ordering temperatures T, are listed in Table 15 [85W3].

Fig. 150. Sm,,,-, Fe,. Temperature dependence of the ac susceptibility xac of several melt-spun alloys. The susceptibility was measured in an alternating field of 340 uT at 110 Hz using a Hartshom bridge-type apparatus. The temperatures Tb of the susceptibility shoulders are indicated by arrows [SSY 31.

Sostarich

Land&-BBmstein New Series IIIN9h

Ref. p. 3421

289

6.2.4 Amorphous R-3d (R = Ce, Pr, Nd, Sm)

x =20

(Ndo.soho.zohoo-xFex

4

I

I

I

I

(%.&h.&oFe3o I I -z

I

I

I

I

3

2

t22 c1 0

50

100

150

200

0

250 K 300

50

100

150 T-

l-

Fig. 151. (Pro,soGa,,zo),oFe~o. Temperature dependence of the ac susceptibility xac measured in a rms field of 1 pT and at a frequency of 280 Hz. The solid curve is for the as-cast sample, whereas the broken curve is for a sample heat-treated at 460” C for 5 minutes. The xacvs. T dependence is consistent with microstructural studies, which show on a 400 8, scale the presence of two amorphous phases, namely a PrGa-rich (T,,-8 K) and a PrFe-rich phase (T, -470 K). The drastic increase in the magnitude of the low temperature peak (~8 K) after heat-treatment is believed to indicate that high-T,, phase regions have transformed to the low-T,, phase by crystallization [82H 1, 84Hl]. (Te is the magnetic ordering temperature.)

200

250 K 300

Fig. 152. (Nd,,,,Gao.ZO)lOO-nFe~. Temperature dependence of the ac susceptibility xac for metallic glasses with x = 0, 10,20. The measurements were performed at a frequency of 280 Hz with a driving field of p,He 30 FT. For Nd,,,Ga,, (x = 0) the low-temperature peak is observed in dc measurements at 14 K and an ordinary Curie-Weiss behaviour is found to hold above this temperature. In the alloys with x > 0 the low-temperature peak still appears, but a second peak is apparently being approached slightly above room temperature as the Fe concentration increases beyond 10 at % [84 C 21.Cf. also xacvs. Tfor (Nd,~,,Gar,&&ozo in Fig.215.

( Ndo.so Coa4o190BII

Fig. 153. (Nd,,60Co,,4,,)9,,B10. AC susceptibility xac vs. temperature for a melt-spun amorphous (I) and a crystallized sample heat-treated at 240” C for 15 min (2). The susceptibility was measured with an ac technique in a rms field of 1 pT and at a frequency of 280 Hz. The asquenched sample exhibits a single sharp peak at 38 K, close to that observed in the amorphous Nd6eCo4e ribbons (cf. Fig. 149). After the first crystallization two new phases are formed with ordering temperatures 17 K and 45 K. It is suggested that these phases may be associated with Nd and a ternary Nd-Co-B phase, respectively [85H2].

L2 -1 I

I

I

I

20

40

60

80

TLand&-Biimstein New Series 111/19h

Sdstarich

K

II

290

6.2.4 Amorphous R-3d (R=Ce, Pr, Nd, Sm)

[Ref. p. 342

6.2.4.3 High-field magnetization and susceptibility. Anisotropy constants, Magnetoresistivity. Magnetostriction

160

/I

I

120

b

a

o-

2

1

6

8

1

10

0

2

6

b

PoH-

8

1

10

POH---

Fig. 154. Prree.,Fe,. Specific magnetization u vs. magnetic field H for a series of melt-spun alloys at 20 K. (a) 45 5x $90. All of the data for the Pr-richer alloys (45sxs66) were taken with the sample in a field poHo= 0.2.. -0.3 T prior to cooling from room temperature to 20 K. (b) x = 55. The magnetization curves are labeled with the field Ho to which the sample was subjected prior to cooling from room temperature to 20 K. The magnetization behaviour shown above is typical of that found for alloys with 45 5 x $60 [81 C 31.

125 nm7 kg IOC

15 I

b SC

O

a

2

4

6

PO”-

8

1

10

0

b

2

4

6

8

1

10

POH-

Fig. 155. Nd,OO-xFer. High-field specific magnetization u of several melt-spun alloys at 20 K as a function of the magnetic field H. (a) 45sx1;80. The samples were exposed to fields slightly greater than their room temperature intrinsic coercivities prior to cooling to 20 K. (b) x =60. The magnetization curves are labeled with the field H,, to which the sample was subjected prior to cooling to 20K. Linearity over the entire field range was not obtained until pLoH,=0.3 T, i.e. slightly greater than the room-temperature coercivity of the alloy [81 C 11.

Sostarich

Lsndolt-BBmstcin New Series III~19h

Ref. p. 3421

291

6.2.4 Amorphous R-3d (R = Ce, Pr, Nd, Sm) 1 I

/I ( Pro.80b.dloo-x

I Fe,

1.25 I -p.oo 0.75

0

50

100

150 T-

200

250 K 300

Fig. 156. (Pr,,,,Gao,20)100-xFex. Inverse high-field magnetic susceptibility x,$ vs. temperature for several melt-quenchedsamples.xHFis obtained from fits to the law of approachto ferromagneticsaturation: a=a,,(l-AI/H-AZ/HZ..

.)+xHFH

(cf. introduction) [84C 21.

Table 17. Uniaxial anisotropy constant, K,, and magnetic susceptibility of the paraprocess above technical saturation, xHF, for some metallic glasses containing light rare earths. KU 106Jmm3

XHF

21.5”) 1”) 0.04b) 1.2”)

Ref.

Remarks

84C2 8382 8OSl 85H2

at 20K at 4.2K at 293 K at 4.2 K

10-7m3kg-i 3

3 Calculated with the magnetization-area method from data in [Sl C 31. b, First-order anisotropy constant, K,, estimated from the magnetization curves assuming a hexagonal local symmetry. “) From the law of approach to saturation.

Land&-Biirnstein New Series III/l9h

Sostarich

[Ref. p. 342

6.2.4 Amorphous R-3d (R=Ce, Pr, Nd, Sm)

292

IRelative deviation of the elecFig. 157. Ce7&02.,s. trical resistivity, e(H,T), from its value in zero-field at 70 mK, ~(0, 0.07 K), measured as function of temperature in different applied magnetic fields H on a melt-spun sample. The magnetic field was oriented parallel to the ribbon [82F 11.

is~

I -4

l/l.0 9 d a -1.5

cil ‘-I d"

-12

-2.0

-2.51 0

-8

I 0.1

I &8

I 1.2

1

-16 0

11.6

P,HFig. 158. PrrFe80-rB20. Magnetic field dependence of the reduced transverse magnetoresistivity, A&a, of two melt-spun alloys measured at 290K in “low” constant fields up to 1.6T by a four-point dc technique with an accuracy of 1. lo-‘. The magnetic held was in the plane of the ribbon [88 C 23.

8

12

16

20 1

PoHMagnetic field dependence of Fig. 159. PrzFe,,B,,. the reduced transverse magnetoresistivity, Ael/eo, for a melt-spun sample measured at 77 K and 290 K in high pulsed magnetic fields using a compensation method with an accuracy of 7. 10W4.The magnetic field was in the plane of the ribbon. The dependence of the transverse magnetoresistance on magnetic held was found to be typical of ferromagnetic alloys [88 C2]. See also Fig. 158.

Sostarich

Land&-BBmstein New Series 111/19h

Ref. p. 3421

6.2.4 Amorphous R-3d (R = Ce, Pr, Nd, Sm) .I@ Oe-’ 300.

250

200

150 I ~100~ 3 (D 50

0

60 :n IU

0

01 01 0

-----. 50

100

c

150

-

I

I

I

I

200 T-

250

‘300

350

K 4

Fig. 160. NdiO,,.,Fe,. Forced volume magnetostriction, awlaH, of several melt-spun alloys as function of temperature. Curie temperatures Tc indicated by arrows were determined by Arrott plots. For x=80 the awlaH value is about 55.10-” Oe-’ at 77 K and increases to about 295.10-l’ Oe-’ at Tc. For alloys with x570 hysteretic magnetostriction vs. magnetic field curves are measured below TH, (broken arrows) [8812]. (Cf. also caption to Fig. 110)

40 .m6

Fig. 161. Sm,Feso-,Bzo. Composition dependence of saturation magnetostriction 1, and coercive field H, of melt-spun alloys at room temperature. The magnetostriction was measured using the three-terminal capacitance method, while the coercive field was determined from quasi-static hysteresis loops taken with a loop tracer at a reversal frequency of 0.02 Hz. The saturation magnetostriction was found to decrease from 37.10m6 for Sm,Fe,,B,, to 12.10s6 for Sm,Fe,,B,, [8815].

Land&-BBmstein New Series 111/19h

40 A/m

35

35

I 30

30

4

I 25

25 *

20

20

151 0

Sostarich

I 12

I

I 3

4

5

A15 6

294

[Ref. p. 342

6.2.4 Amorphous R-3d (R = Ce, Pr, Nd, Sm)

6.2.4.4 Miissbauer effect

I -8

I

I

-6

-4

I

I

I

I

-2

0

2

4

I

mm/s

8

V-

Fig. 162. NdrsFes5. 57FeMdssbauerspectraof meltspun alloy at room temperatureand 77 K. The bar graph in the lower part of the figure showsthe line positions in the Miissbauer spectrumof u-Fe at 77 K. The hyperfine field at 77 K is found to be about 30 T and almost independent of the alloy composition [87S2]. Cf. also Fig. 121.

Table 18. Average s7Fe hyperf’me field, i$,r,,, and isomer shift relative to a-Fe, IS, obtained from MGssbauer-effectinvestigations on some ternary amorphous alloys containing light rare earths and iron.

BhYP

T

25.0 29.5 27.1 30.0 23.7 24.0 18.7 17.4 13.3

IS mms-’

-0.18 -0.22 -0.23 -0.24 -0.23

Ref.

Remarks

82C3 82C3 88Cl 88Cl 88A2 88A2 88A2 88A2 88A2

at 300K at 4.2K ?b ’1 at 300K at 300K at 300K at 300K at 300K

‘) Extrapolated &,rP value at T=OK. b, Hydrogen increases the s7Fe hyperhne field in the amorphous alloy substantially, whereas its influence on the saturation hypertine field is slight in the crystalline phase Nd,Fe,,B.

Sostarich

Land&-B6mstein New Series 111119h

Ref. p. 3421

295

6.2.4 Amorphous R-3d (R = Ce, Pr, Nd, Sm)

a

0

IO

b

-3.5

b

0

0

3.5

mm/s

7.0

20

30

T

40

Bhyp-

Fig. 163. (Pr,,s,Ga,,,,),,Fe,O. (a) “Fe Miissbauer spectrum at 300 K (data points) and a fit to the spectrum using the Window [71 W I] technique (solid line). (b) P(I&,) vs. BhYpcurve giving the hyperfine field distribution deduced from the above spectrum [84C 21. See also caption to Fig. 164.

1 IO

20

30

T

40

Bb’p -

Fig. 164. (Pr,.s,Gao.zo)80Fe,,. (a) “Fe Miissbauer spectrum (points) of an enriched sample at 300 K and fit to the spectrum (solid curve) with the P(BhYp)curve given in (b). (b) Fourier deconvolution of the 300 K Miissbauer spectrum into an internal (hyperfine) field distribution function, P(B,,,). The first peak in the deconvolution curve is attributed to “nonmagnetic” or paramagnetic Fe contributions. The large peak at 25 T represents the magnetic Fe contribution and is 67% of the total intensity. The amorphous (Pro.soGao,zo)soFezo sample was prepared by a splat-cooling technique

a

v-

[82C3].

0 b

IO

20 Bhyp-

30

T

40

Fig. 165. (Pr,,sOGa,,,,),,Fe,,-,. (a) “Fe Mijssbauer spectrum at 300 K (points) and fit to the spectrum using the Window [71 W I] technique (solid line). (b) P(B,,,) vs. Bhypcurve representing the best fit to the above data and giving the hyperfine field probability distribution [84C2]. Seealso caption to Fig. 164. Land&-Biimstein New Series 111/19h

Sostarich

296

6.2.4 Amorphous R-3d (R=Ce, Pr, Nd, Sm)

[Ref. p. 342

(Nd,bxh&o

-1

0

1

mm/s

2

-9

a V28 Fig. 166. (Nd,Fe,.,)seB,,. 57Fe Mksbauer spectra T of severalmelt-spun alloys measuredabove the respective Curie temperatures.A constant-accelerationspec24 trometer with a Co-Pd sourcewas used for the measurement. The alloy samplesfor high-temperature spectra were powdered, mixed with boron nitride and mounted t $0 between beryllium discs in a resistively heated oven IQ? [88 R I].

I -6

I -3

0.05

0.10

I 0

I 3

0.15 x-

0.20

v-

I 6mm/s

16 12 0

b

a25

0.30

Fig. 167. (Nd,Fe,.,)s,.sB,,.s. (a) Room-temperature 57Fe Mijssbauer spectra of three melt-spun alloys; (b) averagehypertine field &, vs. Nd concentration. The spectra were obtained on a conventional constantacceleration spectrometer with a 0.2GBq “Co-Pd source. The &,, values were calculated from distributions of BhYpobtained using a Window [71W I] Fourier deconvolution technique188A 21.Cf. also Table 18.

Sostarich

Land&-BCmstein New Series III/19h

6.2.4 Amorphous R-3d (R = Ce, Pr, Nd, Sm)

Ref. p. 3421

-0.225 -0.250

Ia

/

0.65

t

TI

I

0

I\

0.05

0.10

0.15

0.20

0.25

0.30

x-

Fig. 168. (Nd,Fe,.X)lOO.yB,. (a) Isomer shift IS and (b) quadrupole splitting A obtained by least-squares litting of two independent Lorentzian lines to the Mossbatter spectra (cf. Fig.166). Most values from measurements at 480 K. For samples with Tcz480 K the IS and A values were measured at temperatures T= T,+20 K and then adjusted to 480 K using the experimentally found dependences: dZS/dT= - 7.15(6) . 10e4mm s-r K-’ and dA/dT= -1.00(7).10-4 mm s-l K- i. Isomer shifts are quoted with respect to a-Fe at room temperature [88 R 11.

Land&Bkmstein New Series IIUi9h

Sostarich

297

298

6.2.5 R-3d (R = Tb, Dy, Ho, Er, Tm)

[Ref. p. 342

6.2.5 Alloys with heavy rare earth elements (Tb, Dy, Ho, Er, Tm) 6.2.5.1 Magnetization, magnetic moments, ordering temperatures and type of magnetic order

800

I

600 K

K lb KID-xcox 600,

l-1-1 I 400

I p400

CJ 200

A

200

.

o

0 0 0 0

20

40

60

80

J 00

100 R-

xFig. 169. Tb,ea-$0,. Curie temperature Tc as a function of Co content for several melt-spun alloys: open circles [80B2]; full circle [82A 11.Also indicated by means of error bars are the values T,> 600K given for evaporated Tb-Co films in [75 L l] and by the triangle Tc for the polycrystalline Laves compound TbCo, from [78 K 11.

1001 40 50

60

Fig.170. R1O,,-xFer. Curie temperature T, vs. rare earth concentration for rapidly quenched amorphous ribbons with R = Dy and Gd, respectively [88 M 11.

70 R-

80

90 at% 100

Fig.171. R1cO.,Cox (R=Gd, Dy, Er). Specific magnetization u vs. rare earth concentration in liquidquenched amorphous alloys. The magnetization data were taken at 4.2 K in a field of uoH=1.4T using a Faraday-type magnetic balance [88 Y 11.

Sostarich

Landoh-BBmstein New Series IIIj19h

Ref. p. 3421

6.2.5 R-3d (R=Tb, Dy, Ho, Er, Tm)

299

6 9 !!A at 8 I

6 40

100

80 I 0 60

40 201"

40

I

50

60

70 R-

80

90 at% 100

Fig. 173. RiOOJ!ox. Ferromagnetic and paramagnetic Curie temperatures Tc (open circles) and 0 (solid circles), respectively, vs. rare earth concentration in liquid-quenched amorphous alloys with (a) R = Dy and (b) R = Er. The Tc values were determined from Arrottplots, whereas the 0 data were obtained by fitting the x-l vs. T curves to the Curie-Weiss law. The triangles in the case of Dy-Co alloys mark Tc data from [81 G I] (cf. also Table 19and[88Y2])[88Y 11. Landolt-Biimstein New Series III/l9h

60

70 R-

80

90 at%100

Fig. 172. R1OO-xC~x. Average effective magnetic moment per atom, &, as function of rare earth concentration in liquid-quenched amorphous alloys with (a) R = Dy and (b) R = Er. The aen values were obtained by fitting the x-’ vs. T data to the Curie-Weiss law (cf. Figs. 185; 196). The broken lines are defined by the equation, Pen= [( 100-x)p~n(R)/lOO]‘I’, in which p&R) stands for the effective magnetic moment of the free R3+ ions, whereas the contribution of the Co atoms is neglected [88Y I]. Cf. also [88Y2].

120 K

,-

50

Sostarich

Table 19. Magnetic moments, ordering temperatures and specific magnetization of liquid-quenched R-TM alloys with R = Tb, Dy, Ho, Er, Tm and TM = Mn, Fe, Co, Ni. The type of magnetic order is given only where it is explicitly mentioned in the reference.

Feff.Ra) a “1 PB

PlI

10.2h) 10.4

5.9 b) 4.8 “) 4.7 d) 4.5 “) 5.3 “)

E(1) 8.8 6.2 8.9

3

82 b, 85 110 135 176 215

W) 140

13.0”) 10.81 10.7 11.6

5.4 “) 6.3 d,

58 61

9.4

5.Ob)

113

10.6 10.1

4.5b) 5.9 b) 8.35 d, 5.9 b) 6.4 “)

10.86

Ho&o,,

Er75bs Wd%~ W3Fe3, bFe.+, Er5dX3

K

5.0 b) 4.9 b) 4.8 d, 5.1 b)

10.0

DY,&o,o WoNi3o WgNi3 1 HoegFe3, Ho&%, Hod-h,

5.1”) 7.6(l) at 4.2K 9.8(l) at 60K 5.4 b) 2.5 b) 5.0 b)

0

9.64 9.40 9.20 9.9 “)

4.4 b) 4.7 b) 4.7 “) 4.5 d)

170 . 45

35.(5) 81

Tc,T.

K

240 ‘) 2206) >300 82*) 90 ‘) 90.4 J) 113’) 137.0(5) k) 165’) 210’) 55(5) ‘) 118’) 135’) 135’) 151’) 48 ‘) 43 ‘) 61 ‘) 69.5(5) ‘) 110’) 38(l) 4w ‘) 77 ‘) 1W93

T K

x60’)

u Am’kg-’

Magnetic order

Fig. 180 Fig. 180 130’) Fig. 183

60 ‘)

210’)

“1 aspero

60 ‘)

130’)

Fig. 186 170’)

8)

m.p)

Fig. 185

x55=)

Fig. 189 Fig. 190 225 ‘)

aspero 7

25

35 52 72 39

34(1)9 20 36’) 40C) 47 ‘) 25 ‘)

“1 Fig. 193

87

Fig. 194 120’)

Ref.

81 Bl 81 Bl 85A2 80B2 80B2 82B2 80B2 82A 1,82A2, 8382 80B2 80B2 80B3 81 Gl 81Bl 81Bl 83Al 80B2, 81Gl 82B2 81Gl 82A2,83Al, 83A2q) 81Gl 85Wl 80B3 81 Bl 86Al80B2 85Al 84Bl 79B1, 8lBl 81 Bl 81Bl 83Al

Remarks

&,,,(Fe) = 22.5 T at 4.2 K cf. Figs. 182,219

cf. Fig. 202 cf. Fig. 220

&,,(Fe) = 21 T at 4.2 K cf. Figs. 200, 221 cf. Fig. 202 cf. Figs. 187, 188, 222

cf. Figs. 191; 223 cf. Fig. 192

B,,,.,(Fe) = 7 T at 4.2 K cf. Fig. 195

Table 19 (continued). Peff,R=)

PR “1

0

T,,

PB

PB

K

K

9.81 9.67‘)

4.3 “)

9.3(l)

6.3 “) 7.6 ‘)

9.8 7.5

4.4 b)

3 1w3 22.0(5)

K

12(l)“) 10.3‘) 19.0(5)k)

T

d

K

Am2 kg-’

Magnetic order

speri c4.2

165 ‘)

“1

23 5 0

aspero

Ref.

80B2 78Gl 82B2 83Al,83A3 83A3 82A2 80B3 81Bl

Remarks

cf. Figs. 198, 199 cf. Figs. 203, 204 cf. Figs. 200, 224

‘) The effective magnetic moment, &ff,R, and the magnetic moment, pR,are averages given per rare earth atom. b, At 4.2K and in a field of poH = 1.8T. ‘) Determined from e vs. T dependence. “) Calculated from the value of B given in column seven. ‘) Determined as the temperature of the maximum in the zero-field c vs. T dependence. ‘) At 4.2 K and in a field of p,,H = 14T. This value of e is lower than that at 60 K (cf. Fig. 219). 3 Sperimagnetic for Tf < T< T, and spin-glass-like for T < Tp “) The Peff,aand 0 values are derived from Curie-Weiss plots (x-’ vs. T). ‘) Determined from a2 vs. T plots. j) Temperature of peak in the xac vs. T dependence. ‘) Obtained from Arrott plots (a2 vs. H/a). ‘) Technical saturation value at 4.2 K. “) Asperomagnetic (negligible Co magnetic moment assumed) for Tf < T-c T, and spin-glass-like for T< Tp “) Calculated from the Curie-Weiss constant given in the reference. “) Below Tf the spin-glass-like state coexists with the ferromagnetic one, the former becoming dominant below about 20K. q, pR values of 6.1, 4.5 and 5.5 uB at 4.2, 20 and 40 K, respectively, are given in [83 A 21. ‘) Estimated from zero-field 0 vs. T measurements. ‘) Determined from the saturation magnetization at 4.2K. ‘) Calculated from the effective moment per average .atom, peff, given in the reference. “) Defined as the temperature where the coercive field, H,, goes to zero. “) Derived from the value of magnetization extrapolated to saturation at 4.2 K, as the sample was not saturated in fields up to p,,H = 6 T. “) Alloy behaviour doesnot conform to the Curie-Weiss law. 0 and jjeffVR values are calculated from the lowest-temperature portion of the x- ’ vs. T dependence above T,. Cf. Figs. 188 and 200.

Table 20. Liquid-quenched ternary alloys with heavy rare earth elements, 3d transition metals, and B or Ga as glass formers. Magnetic moments per averaee magnetic atom (ion), R+TM, ordering temperatures and specific magnetization. The type of magnetic order is given only where it is explicitly mentioned in the reference. hf.R+TM

pR+-fM?

0

T,

kl

PB

K

K

10.4‘)

3.97 4.72

82 “) 63 ‘) 69 ‘) 97 ‘) 99 ‘) 101’)

3.97 8.45‘)

4.02 3.90 3.30

TbdN7B8 TblFe79B20 (Tbo.80Gao.20h&020 Dy60Fe30Blo

1.92

DyFe,B WI 8bB8 H%2Fe75.8B16

Fig. 175 H%2F%oB15.8 Ho,.,Fe 82.7 B 15.8 Hoo.,F%.,B,, (Ero.8&ao.2deoBlo

“1

Fig. 175 Fig. 175 Fig. 175 4.67 3.95 3.97 3.45

T,

167 “) 134’) 139C) 140.5(6)“) 180’) 114.38) 463 ‘) 439 ‘) 588 ‘) 69 ‘) 91.58) 400 ‘) 474 ‘) 582 ‘) Fig. 176 525 ‘) 577 ‘) 590 ‘) 20 ‘) 11 ‘) 23 ‘) 31 ‘) 31.5‘) 50 ‘)

Magnetic order

Ref.

Am2 kg-r 124.5d, 148

aspero ‘1

137

‘1

152d) 147.5

:;

137.1

2) spero

81C4 84Cl 82C4,82R 1 84Cl 82C4 82Rl 81C4 84Cl 8264 8682 84Cl 8582 87A2 86A2 85W2 82Rl 86Sl 87A2 86A2 84Dl 85Pl

ub)

179’) spero ‘1

Fig. 174 Fig. 174 Fig. 174 Fig. 174 140.1

Speli

Sp3-i Speli Speli

‘)

130.5 144

12

137.9

h,

84D1, 85Pl 84D1, 85Pl 84D1,85Pl 84Cl 82Rl 84Cl 84Cl 82Rl 84Cl

Remarks

cf. Fig. 209 cf. Fig. 209

cf. Figs. 209, 210 cf. Fig. 212 cf. Figs. 207,208

cf. also Fig. 215 cf. Fig. 216

K according to Fig. 176 cf. Fig. 176 cf. Fig. 176 cf. Fig. 176 cf. Fig. 218 T,r463

cf. Fig. 218 cf. Figs. 218, 228 cf. Fig. 218

Table 20 (continued).

~Ero.65Feo.35)90Blo

ErFe,B Er15Fed% (Er,.lG’e 0.875h0B12Si8

i%ff,R+TM

PR+TM’)

0

T,,

PB

PB

K

K

2.7 ‘)

Fig. 206

7.5(2)‘)

T,

37(3)“1

387 i, 370 3 500 i)

fJb)

Am2 kg-l

Magnetic order

Fig. 206 N aspero (cf. also Fig. 226) speri 108‘)

Ref.

Remarks

79Gl

p(Fe) z 0 assumed

80Hl 87A2 86A2 87Kl

cf. Fig. 178

‘) Calculated from the magnetization values in column six unless otherwise specified. “) osPat 4.2 K obtained from law-of-approach-to-saturation fits unless otherwise specified. “) Derived from Curie-Weiss plots (x-l vs. 7’). “) a,, at 4.2 K obtained by extrapolating the high-field magnetization curve to H = 0. ‘) Temperature of peak in the xac vs. T dependence. ‘) Magnetic structure designated as random spin-glass-like was seento become sperimagnetic or, if p(Fe) r 0, asperomagnetic in high applied magnetic fields. g, Obtained from scaling analysis. “) Cluster-glass with significant chemical short-range order suggested. ‘) Determined from cr vs. T dependence. j) 0, at room temperature. k, At T,=91.5 K - sharp speromagnetic transition to a spin-glass-like state. ‘) Spontaneous moment per magnetic atom. “) From extrapolations based on L? vs. H/a (Arrott) plots. “) Composition mentioned alternatively as (Er,.,,Ga,.,,)s,B,, in [84 C 11.

[Ref. p. 342

6.2.5 R-3d (R=Tb, Dy, Ho, Er, Tm)

304

3 kl

10: ‘Gi 1Am? kg y1

I

I”* 1% 1

bl

0

2

2

6

8

10

0 0

2

6

x-

8

10

x-

Fig. 174. Ho,Feg.+IB,6. Specific saturation magnetization a, at 4.2 K as a function of the Ho content for several melt-spun alloys. The u, values were obtained by extrapolating the e vs. H dependences measured at 4.2 K towardsHe’=0[85Pl].

Fig. 175. Ho,Feg,,.rBlb. Average magnetic moment per metal atom, &+uo, vs. Ho content. Closed circles: values determined from a, at 4.2 K data (cf. Fig. 174). The solid line represents the calculated average magnetic moment, assuming collinear, antiparallel oriented Ho and Fe magnetic moments, with j@o)=lO.3 pa and J(Fe) = 2.05 pa. The dashed line is only a guide for the eye [85P I].

600 K I 550 e 500

450 0

0

2 x-

6

8

10

-2001 0

\ I 2

I 4

I 6

x-

Fig.176. Ho,Fe,,-,B,e. Curie temperature Tc as a function of Ho content for several melt-spun glasses [85P 11.

Fig. 177. Ho$o~~-~B~~. Curie temperature Tc and crystallization temperature Tx of several melt-spun alloys with 0 6 x s 8. Tc values were obtained from curves of specific magnetization squared, u*, vs. temperature. The crystallization behaviour was studied with differential thermal analysis at a heating rate of 11 K/min [88 141.

Sostarich

Landoh-B6msfein New Series llIi19h

Ref. p. 3421

305

6.2.5 R-3d (RF Tb, Dy, Ho, Er, Tm)

175 Am2 kg 150

f

I

I

I\~(RT)

I

125

-I750 L K

100

600 I c

75

450

b

I 0.025

501 0

I 0.050

I 0.075

I 0.100

125 I 6

I 0.125

100

501 0

2

4

x-

6

8

x-

Fig. 178. (Er,Fe,&,B,,Si,. Composition dependence of room-temperature specific magnetization 0 and Curie temperature Tc of melt-spun amorphous alloys. The magnetization was measured with a vibratingsample magnetometer in applied fields up to loH= 1.7 T. The Curie temperature was determined in an applied field of p,H N 10 mT [87 K I].

Fig.179. kFeso-xB,,(R=Dy, Ho, Er, Tm). Specific saturation magnetization a, as function of rare earth concentration for melt-spun alloys at room temperature [88G I].

6.2.5.2 Temperature dependenceof magnetization and susceptibility 15.0

.1p

I

1~

I

I

Tb2Fel_,NI,

Am* 12.5

I

1502 1o.u

~I

I e 1.5 '4

100

5.0 50 2.5 I’

0

I

I

I

I

50

100

150

200

I

c

I

0

250 K 300

su

100

150

200

K 250

l-

i-

Fig. 180. TblOO-xFex. Specific magnetization 0 of two melt-spun alloys (x=30 and 40) vs. temperature. The magnetization was measured while heating the samples in a field of poH=0.9 T by using an adaption of the Faraday method. The broken line was obtained after tield-cooling the x = 30 sample to 4.2 K prior to measurement [81 B I].

Fig. 181. Tb,Fe,.,Ni,. Temperature dependence of the average magnetic moment per Tb ion, jr,,, for some melt-spun alloys. prt, was calculated from the magnetization measured in a low applied field of poH=41 mT. The measurements were performed by an automated force magnetometer (P~H,,,~~= 7 T and 3 K < T < 300 K) [88G2]. 1 p,=9.27~10-24AmZ.

Land&-Biimstein New Series III/lW

Sostarich

6.2.5

306

[Ref. p. 342

R-3d (R=Tb, Dy, Ho, Er, Tm)

160 Am’ kg 120 I 80 b

0

30

60

90 T-

120

150 K 180 I-

Fig.182. TbS7Feh3. Specific magnetization u of a melt-spun alloy as function of temperature. The magnetization was measured in a constant field with increasing temperature after cooling the sample either in zerofield (solid line) or in a magnetic field of poH= 6 T (dashed line). There is a maximum at Tr~60 K in the a(7) dependence of the zero-field cooled sample [85A 21.

0

90 120 150 K 180 IFig. 184. Tb,,Co,,. Spontaneous specific magnetization cr,r (solid circles) and zero-field magnetization crO (open circles) as functions of temperature. A large temperature hysteresis is present in the zero-field measurements. The cr.,,values are derived from isotherms of initial magnetization (cf. Fig. 220) [82A 11.

80 40 I b

Specific magnetization u and Fig. 183. Tb6&oj,. reciprocal magnetic susceptibility xi1 ofa melt-spun alloy vs. temperature. The solid a(7) curve represents a heating curve measured in a field of poH= 0.9 T. The broken u(T) curve is a heating curve, too, obtained after cooling the sample to 4.2 K in the presence of a magnetic field. The measurements were performed by using an adaption of the Faraday method [80 B 21.

0 120

30

60

80 40 0 120 80 LO 0 T-

4 Fig. 185. Dyle&ox. Temperature dependence of poH= 1.4 T specific magnetization and inverse magnetic susceptibility, Q and xi l, respectively, for some liquidquenched alloys. The sample with x=60 is crystalline, whereas the other ones are amorphous. The measurements were performed using a Faraday-type magnetic balance. The open and solid circles represent data taken on heating the samples from 4.2 K after cooling them from room temperature in poH=O and 1.4 T fields, respectively. A field-cooling effect is observed only in the crystalline alloy, but not in the amorphous ones. Ferromagnetic and paramagnetic Curie temperatures, Tc and 0, respectively, are indicated by arrows [88Y 11.Cf. also Fig. 186. Sostarich

Iandolt436msfein New Series III!19h

Ref. p. 3421

200

I

4 xl5 -kg

I

DY,,CO,,

$

307

6.2.5 R-3d (R=Tb, Dy, Ho, Er, Tm)

K3

3

kg I 170

(43

150

b’

140 0 -0

n 100

50

150 l-

200

130 0

250 K 300

Fig. 186. Dy,,Co,,. Temperature dependence of the specific magnetization Q of an amorphous sample measured in magnetic fields of poH= 1.8 T (upper curve) and 0.3 T (lower curve). The open circles are reciprocal paramagnetic susceptibility xi ’ data [84 B I].

35 351 jl$ kg 30

10

20

30

40

50

60 K 70

Fig. 187. DY&o~~. Spontaneous specific magnetization trSP as a function of temperature in the lowtemperature range. The cr,r values were obtained from initial magnetization curves taken in magnetic fields up to p,,H= 14 T (cf. Fig. 222) [83A2].

3.0 106 '631 kg

25

I

2.0

I 20

I

b

1.5-g

15

I

b

0 0

/ /I 100

r----l200 T-

LO: I 300

K T-

Fig. 188. Dy,,Co,,. Temperature dependence of specific magnetization Q and inverse paramagnetic susceptibility xi 1 above Tc- 69 K in an applied field of p0Ha=0.78T[83A2].Cf.also[82A2;83S2].

Land&-BBmstein New Series 111/19h

Fig. 189. Dy,,Ni,,. Temperature dependence of specific magnetization e in applied fields of poHa = 0.3 T (lower curve), 0.9 T (middle curve), 1.8 T (upper curve) and of reciprocal magnetic susceptibility xi ’ for a meltspun alloy. The measurements were performed with increasing temperature in the range 4.2.. .300 K using an adaption of the Faraday method [80 B 31.

Sostarich

[Ref. p. 342

6.2.5 R-3d (R=Tb, Dy, Ho, Er, Tm)

308

200 @ kg

5 lo” 45x kg

150

I

H057Fe43

,‘077Tmt-t

?iij

t b 100

1 755

3 I T$

I b

2 50

0

I

1

-0

50

100

150 l-

200

0 250 K 300

0

30

60

a

90 T-

120

Fig. 190. Ho,,Fe, r . Temperature dependence of the specific magnetization u in applied fields of poH,=0.3 T (lower curve), 0.9 T (middle curve), and 1.8 T (upper curve), and of the reciprocal magnetic susceptibility xi1 for a melt-spun alloy. The magnetization was measured on heating the sample using an adaption of the Faraday method [81 B 11.

I 150 K 180

. 0 b

0.3

0.6

0.9 PO4 -

1.2

1.5 1 i.8

Fig. 191. Ho,,Fe,,. (a) Temperature dependence of the specific magnetization D of a melt-spun alloy in different applied fields Ha. The solid lines represent measurements after zero-field cooling, and the dashed lines are for field-cooled samples. A maximum in the u vs. Tdependence of zero-field cooled samples is observed at T, (Hopkinson effect). With increasing Ha this maximum shifts to lower temperatures and disappears for poHaz2 T(b)[86Al].

I

H057C043

1

I

I

I

0

10

20 l-

30

K

I

Spccitic magnetization u of a Fig. 192. Ho&o,,. melt-spun alloy vs. temperature for different values of the applied magnetic field Ha. The solid lines represent measurements after zero-field cooling. A monotonic decrease of d with increasing temperature is observed when the measurement is carried out in zero-field, too (lowest curve). A maximum in the u vs. Tdependence at a temperature Tt < Tc occurs when a relatively weak field (go Ha = 3 mT) is applied. Tr decreases with increasing Ha and disappears at poHa = 3 T. When the sample is cooled in the presence of the applied field (dashed lines) these thermomagnetic effects are not observed [85A I].

Sostarich

Land&-BBmstein Nca Scrics IIIU9h

309

6.2.5 R-3d (R=Tb, Dy, Ho, Er, Tm)

Ref. p. 3421

T-

T-

Fig. 194. Er,,Fe,,. Temperature dependence of the specific magnetization Q in applied fields of ~~H,=0.3 T (lower curve) and 1.8 T (upper curve), and of the reciprocal magnetic susceptibility 2; 1 for a melt-spun alloy. The magnetization was measured on heating the sample using an adaption of the Faraday method [81 B I].

Temperature dependence of the Fig. 193. Er,sFe,,. specific magnetization c in applied fields of poHa= 0.3 T (lower curve), 0.9 T (middle curve), and 1.8 T (upper curve), and of the reciprocal magnetic susceptibility xi ’ for a melt-spun alloy. The measurements were performed by an adaption of the Faraday method [79 B I].

I

I

Er57 h3 I I unH = 1000mT

20 +

--A-,---

1

--& 15 2 G

u

/ /

E 10

s-

\

iw

mT I

I

0

\

200

/

IO

20

30 T-

1

I

40

50

K 6[I

Specific magnetization 0 of meltFig. 195. Er,,Feb,. spun alloy vs. temperature in different magnetic fields. The temperatures Tr and the amplitudes of the magnetization maxima, depend on the magnetic field applied (Hopkinson effect). The maxima disappear on cooling down from the paramagnetic state in a strong magnetic field (broken lines) [83A I].

Land&-Biimstein New Series III/19h

Sostarich

310 160 &IT kg 80 k0 0

[Ref. p. 342

6.2.5 R-3d (R=Tb, Dy, Ho, Er, Tm)

6 106 G kg ii3 2 0 60

120 4 80

I 40 0 b 120

20 7s

0

4

0

1.5

1’0”Isothermal magnetization curFig. 197. Er,,Co,e. ves, u vs. H, for a liquid-quenched amorphous alloy at various temperatures (cf. also Fig. 196) [88 k 11.

80 40

1.2 1

0.9

0.6

0.3

2 0

120

16 .In 106

80

m3 xi

50 I

x”

0 Fig. 196. Er,eO.,Co,. Temperature dependence of poH= 1.4 T specific magnetization and inverse magnetic susceptibility, u and xc’, respectively, for some liquidquenched alloys. The sample with x=60 is crystalline, whereas the other ones are amorphous. The measurements were performed using a Faraday-type balance. The open and solid circles represent data taken on heating the samples from 4.2 K after cooling them from room temperature in poH=O and 1.4 T fields, respectively. A field-cooling effect is observed only in the crystalline alloy, but not in the amorphous ones. Ferromagnetic and paramagnetic Curie temperatures, T, and 0, respectively, are indicated by arrows [88Y 11.

8 4

0

20

40

60

80

100 K ’ 3

I-

Fig. 198. Er,,Co,,. DC magnetic susceptibility xe of liquid-quenched alloy, as a function of temperature. The susceptibility was measured with a Faraday balance and showed a peak at 12 K, which is taken to be the magnetic ordering temperature of the alloy [78 G I]. 5 106 ‘Gn kg ii3 3 I

Inverse magnetic susceptibility Fig. 199. Er,,Co,,. 1;’ of liquid-quenched alloy vs. temperature. The tit of the data to a Curie-Weiss law (solid line) yields the paramagnetic Curie temperature O= lO(2) K. The susceptibility was measured with a Faraday balance [78 G 11.

Sostarich

1

0

50

100

150 l-

200

250 K 300

Landoh-B6mstein New Series 111/19h

Ref. p. 3421

0

6.2.5 R-3d (R=Tb,

50

Dy, Ho, Er, Tm)

0

100

150 200 250 K 300 lFig. 200. RJ7TM4a (R=Dy, Er; TM =Fe, Co). Inverse oaramafmetic suscentibilitv r, i measured in a field peHf0.68 T;s. temperature. ?‘hl arrows indicate the paramagnetic Curie temperature 0, determined by using tangents (dashed lines) to the low-temperature portion of the measured curves (solid lines) [83A I].

10

20

30

LO

o

K

J-

Fig.201. Er,,N&. DC magnetic susceptibility xs measured in a field p,H=70 mT as a function of temperature. The solid circle represents a value measured after “field-cooling” the sample [80 H 21.

3 90.4K

‘1175K

R65C035 10.3 K

43K I

R=Er

-z

.-Y 5 ru L -; s?

lb

R=Oy

AJ 30

Nd

z a F -Lz x”

Gd

,\, LO

I 9

170 K 190

17

I 30 K

T-

Fig.202. R&o,, with R=Gd, Tb, Dy. AC susceptibility (v=35 Hz) of melt-spun alloys vs. temperature. The measurements were performed with a standard ac bridge. Magnetic ordering temperatures, estimated from the xac vs. T dependences, are indicated. The susceptibility maxima were found to be frequency-dependent [82B2].

Land&Biimstein I-&W series III/l9h

Fig.203. R,,Coa5 (R=Nd, Er). AC susceptibility (v= 35 Hz) of melt-spun alloys vs. temperature. The measurements were performed with a standard ac bridge. The xac peak temperatures, Tp= 10.3 K for R=Er and 31.7 K for R=Nd, were found to be frequencydependent [82 B 21(cf. also Fig. 204).

Sostarich

312

[Ref. p. 342

6.2.5 R-3d (R=Tb, Dy, Ho, Er, Tm)

10.2, 14

NO

35

350

1400 3500 Hz14000 35000

Fig.204. Er,,Co,,. Temperature of the ac susceptibility peak, Tr! as a function of the measuring frequency v (cf. Ftg.203). Tp increases with v at a rate AT,,/Av=O.O6 K per decade of frequency. This frequency dependence of Tp is interpreted as a sign of a spin-glasstype magnetic order [82 B2].

2.5 .I03 Ln Am? kg I b

I

1.5

0.9

1.0

0.6

I

3.6 l/l,

0.3 "?+ 0.8

1.0

-1 %I

6;;

#e 0

I

\ /I .^ 4U

I ^^ bU

80

K

l-

-

Fig. 205. HoXFegq.XB,6. Specific magnetization a vs. reduced temperature, T/T,, for melt-spun alloys with various Ho concentrations. The measurements were made with a vibrating-sample magnetometer in the temperature range 4.2.. .300 K. At higher temperatures Forster probes were used [85P I].

Fig.206. (Er,,,,FeO,s&,,,B,,. Square of spontaneous magnetization CT& and inverse paramagnetic susceptibility xi 1 vs. temperature. The magnetization was measured by a vibrating-sample magnetometer, and cr.‘,was obtained by extrapolating to zero field the nearly linear high-field portions of the a2 vs. H/a isotherms. The magnetic ordering temperature is estimated to be 37(3) K. Susceptibility measurements were made with a Faraday balance. A tit of the susceptibility data to the Curie-Weiss relation xs = Njp~rr2[3kB(T-@)]- r yields &rr,ar+rc=7.5(2) pB, the effective magnetic moment per average magnetic ion [79 G I].

Sostarich

Landolt-BBmstein NenSeries 111/19h

Ref. p. 3421

6.2.5 R-3d (R=Tb, Dy, Ho, Er, Tm)

II

~------QIS -__ x&.J /‘I 100

lb58 Mh

----------_ / 150 i-

313

ho

I 200 K

30 mT 0

T-

Fig. 207. Tb5sFeisAl14B10. Field-cooled ac susceptibility x.= vs. temperature in various dc applied magnetic fields. The solid lines are for the in-phase component, xi,, and the broken line for the out-of-phase component, By definition XL, of the ac susceptibility. x = [(xi,)‘+ (x,)~]“~. For larger values of p,H (18 and 3rmT) a distinct shoulder is seen in xi, at T> Tpeak= T,. The data were obtained at a frequency of 280 Hz and in rms fields of about 10 uT [85 S2].

Fig. 208. Tb,,Fe,,Al,,B,,. Temperature dependence of xl, the linear susceptibility for H=O (upper curve), and of x:, the nonlinear susceptibility, for poH=18 mT (middle curve) and u,H=6mT (lower curve). By definition x.,=&-x: [85S2]. Cf. also Fig. 207.

0.30 I 0.25 y 0.20 t-G 0.15

(a) AC suscepFig.209. (Tb,.eoGao.ZO)loo-.Fe,. tibility vs. temperature for rapidly quenched foils with various Fe contents. The glass with x=0 is actually (Tbo,soGao,zo)sOBIo. The scale on the vertical axis is normalized to that for similar Gd alloys (cf. Fig. 75) and all the measurement details are the same. The susceptibility peaks occur at 63,97,134, and 180 K for the samples with x=0, 10, 20, and 30, respectively. (b) shows results of measurements on the x = 20 sample in which the magnetic field was applied in the parallel (1I) and perpendicular (I) orientation. The large difference in ,yacfor the two orientations suggests that the value of xacis controlled by demagnetization effects. This is interpreted as indicating a large true susceptibility, x = dM/dH,, where Hi = H,,-NM is the magnetic field in the material and N is the demagnetization factor, the sample with x = 20 coming short of a ferromagnetic-like state [84C I].

Land&-Biimstein New Series 111/19h

U.&U

N-l 0.30

I y 0.20 x" 0.10

Sostarich

0

0

50

100

150

200

250 K 300

6.2.5 R-3d (R = Tb, Dy, Ho, Er, Tm)

[Ref. p. 342

( Tb 0.80Ga 0.20180Fe20

0

50

100

150 T-

200

250 K 300

Fig.210. (Tb,,,,Ga,,,,),,Fe,,. Temperature dependence of the dc susceptibility xs measured by the Faraday technique as the temperature was raised: (I) after cooling the sample in zero applied magnetic field; (2) after cooling in an applied field of poH=70 mT. The vertical arrow indicates the ordering temperature T, obtained from ac susceptibility measurements (peak in xBc,cf. Fig. 209) [84C 11. 100

125

150 T-

175

200

225 K 250

Fig. 211. (Tb0,soGa,,20),,Fe,,. AC susceptibility vs. temperature for melt-quenched alloy. The susceptibility was measured at 280 Hz. The amplitude of the ac field Hat was pLoHa,= 10 pT and a dc field H was applied parallel to Ha,. The top set of curves gives the total susceptibility, xaE, for poH=O, 4.8, 7.8, 12.0, 18.0, and 28.8 mT (top to bottom). The bottom set of curves gives the nonlinear susceptibility, fc, for ~~8328.8, 18.0, 12.0, 7.8, and 4.8 mT (top to bottom). (Here fc =&--x,,, with xl, the linear and xsc, the total susceptibility). The peak ofXaccorresponds to 0.10 N- ‘, where N is the demagnetization factor [86 S 21.

T,(Hl/T,

(0)----c

Fig.212. (Tb,s,Ga0,2,,)soFe,,. Field dependence of the ac susceptibility peak temperature Tr. Meltquenched (Tb o.&ao.zohoFe20 develops a random, spin-glass-like magnetic order below Tr. The curve is a tit to the experimental data ofthc form,

H= W-~,W/~,(0I1’,

with poHo=700.3 mT, 7’,(O)= 140.5 K,