L-jli

0 0.2 0.3 K 04 0 IO 20 30 K 40

/- 7-

Fig. 77. PrCu,. Magnetic molar susceptibility x,,, vs. Fig. 78. PrCu,. Magnetic molar susceptibility x,,, vs.

temperature at H = 110 Oe and 1100 Oe [72A 21. temperature in the three principal directions at 1 kOe [76 A2].

0.12

Land&Biirnstein New Series III/l9el

40 2.6.2.1.1 Rare earth compounds: R,Cu, [Ref. p. 501

60 mol

I GJ

50

0 10 20 30 LO K 50

Fig. 79. PrCu,. Reciprocal magnetic molar suscepti- bility xi ’ vs. temperature [72 A 23.

2.0 uLs I ^1.5

L 1.0 9”

0.5

0 10 20 30 40 50 kOe 60

H-

Fig. 81. PrCu,. Magnetic moment per Pr ion, pPr, vs.

magnetic field along each principal axis of a single crystal at T=4.2K[79H3].

10.0 40’

9 cm3

I Tg 5.0

0 ¹⁰⁰ 200 300 K 1

Fig. 80. PrCu,. Reciprocal magnetic mass suscepti- bility ,y;’ vs. temperature along each principal axis of a single crystal [79 H 33.

0 5 ^{10 15} 20 25 30 K 35

Fig. 82. PrCu,. Electrical resistivity,p-e,,vs. temper- ature in the three principal directions at low temperatures [76A 2-j.

12 J mol K

10

I 8

c, 6

0 2 6 8 K 10

T-

Fig. 83. PrCu,. Specific heat per mole, C, vs. tempera- ture between T=0.3 K and 10 K. The solid line represents a molecular field calculation [74 W 11.

Landolt-BCmstein New Series 1II’IAl

Ref. p. 5011 2.6.2.1.1 Rare earth compounds: R,Cu,

Fig. 84. PrCu,. Thermal strain s=Al/l vs. tempera- ture along the three principal axes below T=15K [76A 23.

I I I I I

2 4 6 8 10 '12 16 K T-

NdCu,

I. CeCu,: orth D$i-Imma a = 4.387(5) A, b = 7.059(5) A, c = 7.420(5) A [63 S 11.

Additional literature [83 C 11.

II. Antiferromagnetic - paramagnetic

TN

K

Qa

K

Qtl

K

Qc

K

Peff Ccn/Nd

PS pa/Nd

Ref.

3.56 1.9 ‘) 6482

6 17 -16 -4 3.53 79H3

‘) Extrapolated from 80 kOe to infinite field at 4.2K.

In the table, O,, Ob and 0, are the paramagnetic Curie temperatures deduced from the reciprocal magnetic susceptibilities along the a, b, and c axis, respectively.

x-‘(T): Fig. 85;

p(H):

Fig.

86 [79H 1, 79H 33.

10.0 40"

9 cm3

I 7.5

Tg 5.0

0 ₁₀₀ 200 300 K 400

T-

Fig. 85. NdCu,. Reciprocal magnetic mass suscepti- bility 1; ’ vs. temperature along each principal axis of a single crystal [79 H 31.

2.0 1 I I I I I I

0 10 20 30 40 50 kOe 60

H-

Fig. 86. NdCu,. Magnetic moment per Nd ion, pNI, vs. magnetic field along each principal axis of a single crystal at T =4.2 K [79 H 31.

Land&-Biirnstein

New Series III/19el Kaneko

42 2.6.2.1.1

Rare earth compounds: R,Cu, [Ref. p. 501

SmCu, I.

II.

IV.

CeCu,: orth DzE-Imma a = 4.360(5) A, b = 6.925(5) A, c = 7.375(5) A [63 S 11.

Antiferromagnetic - paramagnetic TN

K

9P) 21.7

x- ‘(7’): Fig. 87, P~H): Fig. 88 [79 H 1, 79 H 31.

Electrical resistivity TN=21.7K [8811-j.

PEff ua/Sm

temperature-dependent

PS u&m 0.1 1) 0.06 2, 0.311b

Ref.

6432 79Hl 88113) 89M14)

‘) At 80 kOe at 4.2 K.

2, At 52 kOe at 4.2 K.

3, Temperature dependences of anisotropic magnetic susceptibilities x0, xb and xc of a single crystal are measured. A xD vs. T curve has a peak at T=21.7K, but 1. and xc decrease monotonously with increasing temperature.

4, Magnetization of a single crystal is measured at 4.2K in magnetic fields up to 270 kOe.

Magnetization curve under H/b axis shows a metamagnetic transition at H= 225 kOe. p, is obtained at 270 kOe.

Temperature dependence of Q along the c axis has two anomalies at 16.5 and 21.7 K (= TN).

The anomaly at 16.5 K appears to be due to a first-order phase transition [SS I I].

Specific heat TN=21.7K [8811].

C(T) has three distinct anomalies at 9.4, 16.5 and 21.7 K (= TN) [88 I I].

Magnetoresistance

Shubnikov-de Haas oscillations are observed [86 M I].

Ap(H at 4.2 K: Figs. 89 and 90 [86 M 11.

The observed Shubnikov-de Haas oscillation for H 11 a indicates that there are two frequencies, 0.68 MG and 0.82 MG, while for H 11 b there is a single frequency, 1.25 MG, indicating small cross sections of the Fermi surface. The dips in AC/Q for H 11 a (I II c) at about 40 kOe and 60 kOe are due to a Shubnikov-de Haas oscillation of 0.2 MG. The angular dependence of AQ/Q at a constant field (H = 82 kOe) shows sharp minima for Hlla in the ah plane(I/c)and Hllc in the bc plane (I/a). These results suggest the existence of open orbits [86 M I].

1

0 50 100 150 200 250 300 K : T-

Fig. 87. SmCu,. Reciprocal magnetic mass suscepti- bility 1; ’ vs. temperature at 52 kOe [79 H 33.

O.OE

I

^{E 0.04 JlB}

s”

0.02

/

0 10 20 30 40 kOe !

H-

Fig. 88. SmCu,. Magnetic moment per Sm ion, psm.

vs. magnetic held at T=4.2 K [79 H 33.

Landoli-B6rnwin New Scris 111 19~1

Ref. p. 5011 2.6.2.1.1 Rare earth compounds: R,Cu, 43

8

1

SmCuz

L

IF; ..a

LHllc_

1

T=CfK

22

0

0 20 40 60 80 kOe 1

H-

a

3

I

k y 8 2

0

I

Fig. 89. 4 SmCu,. Transverse magnetoresistance, A@/@, vs. magnetic field at T=4.2K. The experimental con- ditions are indicated in the figure. The Shubnikov- de Haas oscillations are observed for IT/la and jlb(Iljc).

The angular dependence of AQ/Q at a constant field (If= 82 kOe) shows sharp minima for H Ila in the ab plane (I/c) and Hllc in the bc plane (Illa) [86M I].

I-

,-

I-

l-

20 40 60 8U kUe 1

H-

Fig. 90. SmCu,. Transverse magnetoresistance, A@/@, vs. magnetic field at T=4.2 K, showing the Shubnikov- de Haas oscillations. The experimental conditions are indicated in the figure. Arrows for the H II a curve indicate the dips at about H =40kOe and 60 kOe [86 M 11.

Landolt-BGmstein

New Series III/l9el

Kaneko

44

2.6.2.1.1 Rare earth compounds: R,Cu, [Ref. p. 501

E&u, I.

II.

IV.

CeCu,: orth D:,8-Imma a=4.45(1)& b=7.25(1)& c=754(l)A [63Sl].

Additional literature [85 C 63.

Antiferromagnetic - paramagnetic

T,=l3...15K [68Wl], pcrr=7.4u,/Eu, pEU=5.8ua [64S2].

pEU is obtained at 80 kOe at 4.2 K.

p(H): Fig.91 [64S2].

Miissbauer effect on “‘Eu

IS= -0.88(2)cms-’ at 4.2K relative to “‘Sm,O, source [68 W I], -0.79(l)cms-’ relative to “‘SmF, source [77 V 11.

Hhyp=196(10)kOe at 1.8K, 189(8)kOe at 4.2K [66Wl].

6 us

0 20 40 60 ^kOe 80

H-

Fig. 91. EuCu,. Magnetic moment per Eu atom, pEu, vs. magnetic field at T=4.2 K [64S2].

Gdcu, I.

II.

IV.

CeCu,: orth D$E-Imma a =4.320(5) A, b = 6.858(S) A, c= 7.330(5) A [63 S 11.

Additional literature [83 C 23.

Antiferromagnetic - paramagnetic

TN = 41 K, pelf = 8.4 u,/Gd, pGd = 6.0 ua [64 S 21.

pGa is obtained at 80 kOe at 4.2 K.

a(T): Fig. 92 [81 L 33, p(H): Fig. 93 [64S 21.

Forced magnetostriction

l,;(H), A,(H) at 4.2K: Fig. 94 [81 L3].

Specific heat

T,=4OK, C,,,=l54(5)Jmol-‘K-i at TN [85L3, 85L4].

C,,,(T): Fig. 95 [85 L4].

Thermal expansion [81 L 3, 85 L 3, 85 L43 a,,,=27(1). 10m6 K-’ at TN [SS L4].

Al/l vs. T: Fig. 96 [85 L4].

a&T): Fig. 97 [85 L4].

Pressure effect on TN and a(T) dT,/dp= -0.2(2)K bar-’ [81 L3].

u(T) at 1 bar and 5 k bar: see Fig. 92.

Landolt-B6msrein New Scricc III 19~1

Ref. p. 5011 2.6.2.1.1 Rare earth compounds: R,Cu, 45

6.5 Amr kg

8.0

I 7.5 lo

7.0

1

30 34 38 42 46 K 50

T-

Fig. 92. GdCu,. Magnetic moment per kilogram, u, vs. temperature in H = 10.6 kOe at p = 1 bar and 5 kbar [81 L 31.

35

*‘O“

Gd _Cu2

30 T= 4.2 K

-5

0 2 6 6 T IO

W -

Fig. 94. GdCu,. Forced magnetostriction, A,, and A,, vs. magnetic field at T=4.2K [81 L3].

6

0 20 40 60 kOe 80

H-

Fig. 93. GdCu,. Magnetic moment per Gd atom, pod, vs. magnetic field at T=4.2 K [64 S 21.

If J

iGiT

14

Ii

I

_F ^l[ E

c:

E

4

2 j-

i- ,_

l-

I-

,-

0 IO 20 30 40 K !

T-

Fig. 95. GdCu,. Magnetic contribution to the specific heat per mole, Cmag, vs. temperature [SS L 41.

Land&-Bb;mstein New Series 111/19el

46 2.6.2.1 .I Rare earth compounds: R,Cu, [Ref. p. 501

60 .lC."

50

I 10

: 30 d

2c

10

0 20 40 60 K 80

T-

P "0

0 Ooo "

0 10 20 30 40 50 K

I-

Fig. 96 GdCu2. Thermal expansion. A//1, vs. tempcra- Fig 97. GdCu,. Magnetic contribution to the coeffi- ture [SS L43. cient of linear thermal expansion, CL,,,,~, vs. temperature

[SS L 43.

TbCu,

I.

CeCu,: orth Dz,8-Imma a=4.310(5)& b=6.825(5)& c=7.320(5)A

[63S

1).

Additional literature [71 B 2).

II. Antiferromagnetic - paramagnetic

r,

⁰

Q,

K K K

Qb

K

Q,

K

PCU ua/rb

PS u,JTb

Ref.

54 9.8 7.4’) 64s2

53.5 35 2, 76 -6 36 9.50 8.8’) 79H1, 7982

51 31 9.6 82L3

t) Extrapolated from 80 kOe to infinite magnetic field at 4.2 K.

2, Calculated using 0 = l/3(0, + 0, + 0,).

3, Along the a axis at 4.2 K.

In the table 0,. 0, and 0, are the paramagnetic Curie temperatures deduced from the reciprocal magnetic susceptibilities along the o, b and c axis, respectively.

dT): Fig. 98; x-‘(T): Fig. 99; a(H): Fig. 100 [79 H 1, 79 H 21 H,(T): Fig. 101 [82 L 31.

Pressure effect on TN and a(T) - aT, = -O.l(l)Kkbar-’ [Sl L3].

ap

III. Magnetic structure

Neutron diffraction: TN z 54 K [71 B 23, 55 K [86 S 33.

7;,=16K. T,,=47K [86S3].

Magnetic intensity I,(T): Fig. 102 [71 B 23.

Ref. p. 5011 2.6.2.1.1 Rare earth compounds: R,Cu, 47

IV.

T

Type ‘1

Propagation Polarization _PTb

PB

Ref.

8.9(4) ‘) 7lB2 8.9 3, 79Hl,79H2

<‘11 AI11 Ilo 8.8 4, 8633

%***1;2 AI1 Ila

T,,...T, AI (1/3>0,0)

lla

I)

AI: single longitudinally modulated structure with modulation vector 1/3a*.

AII: mixed structure with AI and AIII.

AIII: collinear antiferromagnetic structure with the magnetic unit cell 3a x b xc and the Tb moments parallel to the a axis.

‘) From neutron diffraction at 5.5 K.

“) From neutron diffraction at 4.2 K.

“) From neutron diffraction below 16 K.

In the table the magnetic order-order transition temperatures q;, and q1;2 correspond to the AIII~AII and AII+AI transitions, respectively.

Magnetic structure: Fig. 103 [79 H 1, 79 H 21.

Magnetic structures below 16K, and between 47 and 55 K: Fig. 104 [87L2].

Additional literature [87 D I].

Magnetostriction

I,,(H) and I,(H) at 4.2K: Fig. 105 [Sl L 31.

Electrical resistivity Q(T): Fig. 106 [78 P2].

Specific heat TN=48.5K [85L3].

C/T vs. T: Fig. 107 [85 L 31.

Thermal expansion [Sl L 3,85 L 31.

U(T): Fig. 108 [85 L 31.

The three different contributions to the coefficient of thermal expansion are separated: (i) the l-type contribution, (ii) lattice contribution and (iii) third contribution. It is not yet clear whether the relatively large and negative contribution (third contribution) above 30K is of magnetic origin or not [Sl L 33.

Additional literature [SS K 21.

0 20 40 60 ^{K 80} 0 100 200 300 ^{K 400}

T- IT -

Fig. 98. TbCu,. Magnetic mass susceptibility xg vs. Fig. 99. TbCu,. Reciprocal magnetic mass sucepti- temperature at 5.2 kOe along each principal axis of a bility 1, 1 vs. temperature along each principal axis of a

single crystal [79 H 21. single crystal [79 H 23.

Landolt-Biirnstein

New Series IIIIl9el Kaneko

48 2.6.2.1.1 Rare earth compounds: R,Cu, [Ref. p. 501

203 Gcn?

9

I 150

~ 100

40 50 kOe60 H-

Fig. 100. TbCu,. Magnetic moment per gram, o, vs.

magnetic licld along each principal axis of a single crystal at T= 4.2K [79H2].

20 kOe

18

10

0 10 20 30 10 50 K 60

T-

Fig. 101. TbCu2. Critical magnetic tield, H,, vs. tcm- pcraturc [SZ L 33.

TbCu, v

0.8

I 0.6 ZE

0.L

0 10 20 30 40 5 K 60

I-

Fig. 102. TbCu,. Intensity of magnetic neutron diffraction, I,, vs. temperature for two groups of reflec- tions (hkl): h = 3n + 1 and h = 3n, respectively, where n is an integer. The curves are calculated from a molecular field model assuming J= l/2. There are three sublattices.

1’ and A” arc the intersublattice molecular field coefficient and intrasublattices one, respectively [71 B 23.

Fig. 103. TbCu,. Magnetic structure. 2/3 of magnetic moments of Tb atoms, A and C, in a c plane are aligned along the + a direction (sublattice A, C) and l/3, B, along the -a direction (sublattice B); in the adjacent c planes the magnetic moments of Tb atoms are all reversed and these antiferromagnetic coupled double layers pile up in the c direction [79 H 21.

0 Tb l Cu

Ref. p. 5011 2.6.2.1.1 Rare earth compounds: R,Cu, 49 b TbCu2

I

Fig. 104. TbCu,. Projection of magnetic structures in the (a, b) plane below T= 16 K, and between 47 K < T

< 55 K. Only Tb atoms are shown. The positions in the c direction are i: Z; 2: l-z; 3: zf1/2; 4: -zf3/2 with z=O.547 [87L2].

60 I

pQcm

TbCu,

40

20

0 50 100 150 200 250 K 3

T-

Fig. 106. TbCu,. Electrical resistivity Q vs. tempera- ture [78 P 21.

Fig. 108. TbCu,. Linear thermal expansion coefti- cient CI vs. temperature [85 L 31.

40

*lo-’

35 30 25

t 2c ti

15 IO

5

c _c

2 4 6 8 T IO

!-hlH-

Fig. 105. TbCu,. Forced magnetostriction, III and A,, vs. magnetic field at T=4.2K [81 L 31.

.I.5 J molK2

I 1.0

s 0.5

0 IO 20 30 40 50 K 60

Fig. 107. TbCu,. Specific heat per mole devided by temperature, C/T, vs. temperature in zero magnetic field [85 L 31.

-10

0 20 40 60 K 80

T-

Land&-Bdmstein

New Series IIIil9el Kaneko

50 2.6.2.1.1 Rare earth compounds: R,Cu, [Ref. p. 501

DyCu,

I.

II.

III.

IV.

CeCu,: orth D:,8-Imma a=4.300(5)& b=6.792(5)& c=7.300(5)A [63Sl].

Additional literature [82 F 1, 822 11.

Antiferromagnetic - paramagnetic TN

K 24 31.4 27

‘) Extrapolated from 80 kOe to infinite magnetic field at 4.2 K.

2, Calculated using 0 = l/3(0, + 0, + 0,).

3, Along the a axis at 4.2K.

In the table O,, Qb and 0, are the paramagnetic Curie temperatures deduced from the reciprocal magnetic susceptibilities along the (I, b and c axis, respectively.

fiT): Fig.109; x-‘(T): Fig.110; 4H): Fig.111 [79Hl, 79H2].

There appear two magnetization along the a axis jumps at 4.2 K [79 H 1, 79 H 21.

Magnetic structure Neutron diffraction

The magnetic structures at 5 K and at 15 K are similar to those obtained for TbCu, in the region III or II and in the region I, respectively. But the temperature dependence of the magnetic structure of DyCu, can not be analyzed in detail [87 L 23.

Magnetic structure at 5 K: Fig. 112 [87 L2].

Additional literature [87 K 4-J.

Specific heat

Q Q,

K K

6’) 35

Q, Q, PCff PE Ref.

K K k%PY klPY

10.75 8.7’) 64s2

-17 0 10.3 9.73) 79H1,79H2

83Hl

T,=26.7K [SSL3].

C/T vs. T: Fig. 113 [85L3].

Thermal expansion

The magnetic order-order transition is observed at 19.5 K [SS L 33.

a(T): Fig. 114 [85 L 31.

Pressure effect

Magnetic measurement [83 H 11, Additional literature [SS K 21.

6 Xl-3 cm3 -is-

6

20 LO 60 K 80

I-

Fig. 109. DyCu,. Magnetic mass susceptibility xB vs.

temperature at 5.2 kOe along each principal axis of a single crystal [79 H 21.

10.0 .103

9 cm3

1.5

2.5

0 ₁₀₀ 200 300 K LOO

T-

Fig. 110. DyCu,. Reciprocal magnetic mass suscepti- bility xi ’ vs. temperature along each principal axis of a single crystal [79 H 23.

Kaneko

Ref. p. 5011 2.6.2.1.1 Rare earth compounds: R,Cu,

Gcm3 200 9

I 150

100

~

0 10 20 30 40 50 kOe 60

Fig. 111. DyCu,. Magnetic moment per gram, (r, vs.

magnetic field along each principal axis of a single crystal at T=4.2K [79H2].

1.50 .I molK2

1.25

I 1.00

q 0.75 c,

0.50

0.25

0 5 10 15 20 25 30 K T-

5;

1

Fig. 113. DyCu,. Specific heat per mole divided by temperature, C/T, vs. temperature in zero magnetic field and at H=50kOe [85L3].

b 0)'cU, t

Fig. 112. DyCu,. Projection of magnetic structure in the (a, b) plane at T= 5 K. Only Dy atoms are shown. The positions in the c direction are 1: z; 2: 1 -z; 3: z+ l/2; 4:

-z+3/2 with z=O.547 [87L2].

26 10-s K-1

15

I IO

0

-5

I I I I

3

IO I I I

I I I

20 40 60 K 80

T----c

Fig. 114. DyCu,. Linear thermal expansion coefh- cient a vs. temperature [85 L 31.

Land&-BGmstein

New Series IIIIl9el

Kaneko

52 2.6.2.1.1 Rare earth compounds: R,Cu, [Ref. p. 501

HoCu, I.

II.

III.

IV.

CeCuz: orth Di,8-Imma a =4.280(S) A, b = 6.759(S) A, ^{c =} 7.290(5) A [63 S I].

Additional literature [80 L 1, 85 S 81.

Antiferromagnetic (I) ~ antiferromagnetic (II) - paramagnetic

7;‘) TN 0 0, 0, 0, _Pdf

K K K K K K l+i/Ho

9 10.5

9.8 38 3, 45 30 38 10.4

8.6 11.4

7.0(2) 9.7(2) 4(2) 10.1(l)

7 10

‘) AF(I)sAF(II) phase transition temperature.

‘) Extrapolated from 80 kOe to infinite magnetic field at 4.2 K.

3, Calculated by the relation 0 = l/3(0, + 0, + 0,).

4, Along the n axis at 4.2K.

‘) At 4.4 K and 54 kOe.

In the table 0,. 0,. and 0, are the paramagnetic Curie temperature deduced from the reciprocal magnetic x(T): Fig. 115; x-‘(T): Fig. 116; u(H): Fig. 117 [79Hl, 79H2).

a(T): Fig. llS;T,(H). T,(H): Fig.119 [82G4].

Magnetic structure

In the temperature range of 7( 2 ‘I,)...10 K( = TN), the magnetic structure is commensurate with the unit cell with a wavevector q, =1/3a* and the magnetic moments are aligned along the a axis. Below 7 K two groups of magnetic reflection are observed. The first group is identical to the reflections observed between 7 K and 10 K. The second group may be interpreted in terms ofan incommensurably modulated component along c* with the magnetic moments aligned along the b axis characterized by wavevectors q2=qcc* and 2q, (q,=O.300(5) at 5K) [85S8].

pHo (amplitude along the a direction)= 8.3(2) pn at 5 K, 6.0(2) pa at 8 K [85 S 81.

Temperature dependence of magnetic Bragg peaks [(O,O, O)*qc and (I, i, 0)]: Fig. 120 [80 L I].

Magnetic structures between 7 and 10 K, and below 7 K: Fig. 121 [87 L 23.

Additional literature [82 G 4, 86 S IO].

Electrical resistivity

TN = 11 K [SOB I-J, 9.7(2) K [82 G 4).

T= 8 K [SOB I], 6.7(2) K [82 G 41.

e(T): Fig..l2_2 [8OB 11.

Magnetoresistance

Q(H) at various temperatures: Fig. 123 [80B I]:

Specific heat

T,=9.6K, I;=7K [85L3, 85L5].

C/T vs. T: Fig. 124 [85 L 31.

Thermal expansion a(T): Fig. 125 [85 L3].

Thermoelectric power Q(T): Fig. 126 [82G4].

Pressure effect on d(T)

c(T) at 1 bar and 4 kbar: Fig. 127 [83 H I].

PS pa/Ho 9.2 ‘) 9.6 4, 7.15)

Ref.

6482 79Hl,79H2 8OLl 8264 83H 1

susceptibilities along the a, b, and c axis. respectively.

Kaneko

Landnlr-Fkimctcin

New Serk 111 I9cl

Ref. p. 5011 2.6.2.1.1 Rare earth compounds: R,Cu, 53

20 40 60 K 80

T-

Fig. 115. HoCu,. Magnetic mass susceptibility xg vs.

temperature at 5.2 kOe along each principal axis of a single crystal [79 H 21.

90 Gcm3

To

60

1 50 bIIIIlIl'4

4 5 6 7 8 9 IO K 11 T-

Fig. 118. HoCu,. Magnetic moment per gram, (r, vs.

temperature in different magnetic fields [82 G 43.

10.0 403

9

cm3 1.5

I 5.0 75

2.5

Fig. 116. HoCu,. Reciprocal magnetic mass suscepti- bility xi ’ vs. temperature along each principal axis of a single crystal [79 H 21.

200 Gcm3 --r

I 150

b 100

0 IO 20 30 40 50 kOe 60 H-

Fig. 117. HoCu,. Magnetic moment per gram, u, vs.

magnetic field along each principal axis of a single crystal at T=4.2K [79H2].

0 2.5 5.0 7.5 10.0 12.5 kOe I’

H-

5.0 Fig. 119. HoCu,. Magnetic order-order transition temperature, r, and Ntel temperature, TN, vs. magnetic field [82 G 41.

Land&BBmstein

New Series IIII19el Kaneko

54 2.6.2.1.1 Rare earth compounds: R,Cu, [Ref. p. 501

30

I 25 20 .z z ';; = z 15 -z

10

5

0

6 8 10 12 K

I-

3

14 Fig. 120. HoCu,. Intensity of magnetic neutron diffraction I,. vs. temperature for two peaks, (1iO) and (000)’ [80 L 1-j.

5 10 15 20 25 K 30 I-

Fig. 122. HoCu,. Electrical resistivity e vs. tempera- ture [SOB 11.

b

I ^HoCu2 _{I I} ,

I

I I I

Fig. 121. HoCu,. Projection of magnetic structures in the (u,b) plane between 7K<T<lOK, and below T= 7 K. Only Ho atoms are shown. The positions in the c direction are 1: z; 2: l-z; 3: z+1/2; 4: -z+3/2 with z=O.547. Below T=7 K the Ho magneticmoment in the b direction is modulated along the c axis with wavevector 0.3 c* [87 L 23.

0 20 VJ 60 80 kOe 100

H-

Fig. 123. HoCu,. Transverse magnetoresistance e vs.

magnetic held at various temperatures [SOB 11.

Kaneko

Ref. p. 5011 2.6.2.1.1 Rare earth compounds: R,Cu, 55

2.4 7 J molKl

2.0

I 1.6

Q 1.2 L.l

0.8

0.4

0 20 40 60 K 80

T-

Fig. 125. HoCu,. Coefficient of linear thermal expan- sion CI vs. temperature [SS L 31.

0 _{5 IO 15 20 25 3U K 35} T-

Fig. 124. HoCu,. Specific heat per mole divided by temperature, C/T vs. temperature in zero magnetic field and at H = 50 kOe [85 L 31.

6.0 ClV

?i- I 4.5

~ 3.0

1.5

0 50 100 150 200 250 K 300

T-

Fig. 126. HoCu,. Thermoelectric power Q vs. temper- ature. Insert: details of low-temperature region [82 G 41.

I b

kbar

i P ^9,

14 .O 4 8 12 16 K 20

T-

Fig. 127. HoCu,. Magnetic moment per kilogram, 6, vs. temperature at pressure of 1 bar and 4 kbar at H=4.2kOe [83H 11.

E&u,

I. CeCu,: orth D$i-Imma a = 4.275(5) A, b = 6.726(5) A, c = 7.265(5) A [63 S 11.

Additional literature [70 B I].

II. Antiferromagnetic (I) - antiferromagnetic (II) - antiferromagnetic (III) - antiferromagnetic (IV) - paramagnetic

Ref.

11 9.35 5.6 ‘) 64S2

13.5 36 ‘) 18 53 36 9.40 8.9 “) 79H1, 79H2

‘) Extrapolated from 80 kOe to infinite field at 4.2 K.

“) Calculated by the relation 0 = l/3(0, + 0, + 03.

3, Along the b axis at 4.2K.

In the table, O,, 0, and 0, are the paramagnetic Curie temperatures deduced from the reciprocal magnetic susceptibilities along the a, b, and c axis, respectively.

x(7’): Fig. 128; x-‘(T): Fig. 129; a(H): Fig. 130 [79H 1,79H2]

x..(T) and Q(T) curves show three anomalies at TN = 11.8 K, 1;r = 6.1 K and KI;, = 4.3 K [84 S 41. TN = 11.5 K, 7;,=6K, ‘1;,=4.1K, ‘I;,=3.3K [85L5], 1;z6K [83Hj], from a(T).

/

Land&-Bijmstein

New Series III/l9el

Kaneko

56 2.6.2.1.1 Rare earth compounds: R,Cu, [Ref. p. 501

III.

IV.

Magnetic structure

Neutron diffraction for powdered sample arc carried out between 1.5 and 40 K. The magnetic structure is a rather complicated antiferromagnetic one with a strong temperature dependence of the propagation vector [87 L 21.

Additional literature [84 S4].

Specific heat

T,=llSK, T,=6K, 7;,=4.1 K, 7;,=3.3K [85L3, 85L5].

C,,,(T): Fig.131 [85L3].

C(T) depends on magnetic field [SS L 33.

Thermal expansion a(T): Fig. 132 [85 L 31.

Pressure effect on a(T)

o(T) at 1 bar and 4kbar: Fig. 133 [83 H 1-j.

125 .lOP - cm3

9

I 7.5 N”

5.0

2.5

0 20 10 60 K 80

T-

0 100 200 300 K 4

T- Fig. 128. ErCu,. Magnetic mass susceptibility xr: vs.

temperature at 5.2 kOe along each principal axis for a

Fig. 129. ErCu,. Reciprocal magnetic mass suscepti- single crystal [79 H 21.

bility ,Y;’ vs. temperature along each principal axis of a single crystal [79 H 23.

2c:

G:ir’

9 1 153

b 10%

50

0 10 20 30 LO 50 kOe I H-

Fig. 130. ErCu?. Magnetic moment per gram, a, vs.

magnetic ticld along each principal axis of a single crystal at 7=4.2 K [79 H 21.

10.0 403

9 cm3

I 5.0 7s

2.5

12.5 J molK

10.0

I I.5 c: z

5.0

0 5 10 15 20 25 K :

Fig. 131. ErCu,. Magnetic contribution to the specific heat per mole, Cmapr vs. temperature, after subtracting the Schottky contribution [85 L3].

Kaneko

Ref. p. 5011 2.6.2.1.1 Rare earth compounds: R,Cu,

-15 0 20 40 60 K 8

@ 8.5 kg 1.5

I 6.5 b

5.5

0 3.5 0 12 16 K ;

Fig. 132. ErCu,. Linear thermal expansion coefficient Fig. 133. ErCu,. Magnetic moment per kilogram, (T, tl vs. temperature [85 L 31. vs. temperature at pressures of 1 bar and 4 kbar at

H=4.2kOe [83H I].

TmCu,

I. CeCu,: orth D:i-Imma a = 4.266(S) A, b = 6.697(5) A, c = 7.247(5) A [63 S 11.

Additional literature [86 S 91.

II. Antiferromagnetic (I) - antiferromagnetic (II) - antiferromagnetic (III) - antiferromagnetic paramagnetic

TN=6.3K, T1=4.3K, T,,=3.9K, T,,=3.3K, @=24(2)K, peff=7.2(2)pB/Tm above 50K [86S9].

pen= 7.49 us/Tm, ps = 4.2 piJIm [64 S 21.

ps is the value extrapolated from 80 kOe to infinite field at 4.2K.

Additional literature [88 S 41.

III. Magnetic structure

IV.

Neutron diffraction for a powdered sample are carried out [87 L 21.

Magnetic structure: Fig. 134 between 4 and 6 K [87 L 21.

Electrical resistivity, specific heat [86 S 93 TN = 6.3 K [86 S 91.

‘I;, =4.3 K, T2 = 3.9 K, & = 3.3 K [86 S 91.

Additional literature [SS Z 2-J.

b t

TmCu2

m -

I I I

2 / 4% '\ { 'k A J I 4K<T<6K I I \4k / / ,I y / 4 i

I I -U

Fig. 134. TmCu,. Projection of magnetic structure in the (a, b) plane between 4 K < T< 6 K. Only Tm atoms are shown. The positions in the c direction are 1:~;

2:1-z; 3:z+1/2; 4: -z+3/2 with z=O.547 [87L2].

Land&-Biirnstein New Series 111/19el

58 2.6.2.1.1 Rare earth compounds: R,Cu, [Ref. p. 501

YbCu,

I. CeCu,: orth

D:t-Imma

a=4.28(1)& b=6.76(1)& c=7.40(1)A [63S 11.

Additional literature [71 111.

II. Paramagnetic down to 1.4K [64S 23.

pYb =0.07 pB at 4.2 K and 80 kOe [64 S 21

x-‘(T): Fig. 135; x(7’): Fig. 136; a(H): Fig. 137 [73K 11.

Additional literature [76 K 1, 77 K 11.

IV. Photoemission [87 F S]

Additional literature [80 J 2, 80 J 3, 82 J 11.

1.2 Xl6 - 9 cm3

1.0

0 200 400 600 800 K 1000

T-

Fig. 135. YbCu,. Reciprocal magnetic mass suscepti- bility xi’ vs. temperature [73 K 1).

3 .10-t

I

?

?-? 1

0 200 500 600 800 K 1000

T-

0.6 Gcm3 t 9 Ob

b 0.2

0 50 100 150 200 250 kOe :

H-

300 Fig. 136. YbCuz. Magnetic mass susceptibility xs vs. Fig. 137. YbCu,. Magnetic moment per gram, 6, vs.

temperature after correction for Yb,O, [73 K 11. magnetic field at T=4.2K [73 K 11.

LUCU,

I. CeCu,: orth DIf-Imma a=4.245(5)& b=6.627(5)& c=7.220(5)A [63S 11.

II. Paramagnetic down to 1.4K [64S2].

pLu =O.Ol pB at 4.2 K and 80 kOe [64 S 21.

Kaneko

Ref. p. 5011

CeCu,

2.6.2.1.1 Rare earth compounds: R,Cu, 2.6.2.1.1.3

RCu,

R=Ce

59

I.

II.

IV.

CeCu,: orth Pnnm or Pnn2 Additional literature [52 B I].

n=4.54(1)& b=8.10(1)& c=9.19(1)_A [64R 11.

Paramagnetic down to 100 K.

No magnetic ordering is observed down to 1OOK [79 P 11.

@=-12K, peff=2.52@L!e, ~o=138~106cm3mol-1, using x=C/(T--O)+X~ [79Pl].

x-l(T): Fig. 138 [79P 11.

Additional literature [63 0 1, 83 C 41.

NMR of 63Cu

K(T), K(X): Fig. 139 [79P 11.

AH(T): Fig. 140 [79P 11.

Additional literature [83 C 41.

I

200 400 600 K I

T-

Fig. 138. CeCu,. Reciprocal magnetic mass suscepti- bility xi1 vs. temperature [79 P 11.

0 100 200 300 400 K 500

T-

Fig. 139. CeCu,. Knight shift of 63Cu, K, vs. tempera- ture and magnetic mass susceptibility xp. K is re- ferred to 63Cu in CuCl powder [79 P 11.

9

I

Oe ⁸ x -7

6

0 100 200 300 400 K 500

T-

Fig. 140. CeCu,. 63Cu NMR linewidth AH vs. tem- perature [79 P 11.

Landolt-Bknstein

New Series IIIIl9el

Kaneko

60 2.6.2.1.1 Rare earth compounds: R,Cu, [Ref. p. 501 2.6.2.1.1.4

RCu,

R = La, Ce, Pr, Eu, Gd, Tb, Dy, Ho, Er, Tm LaCu,

I. CaCu,(DZ,): hex D&,-P6/mmm a=5.186& c=4.110& c/a=0.791 [71 B43.

Additional literature [61 D 1, 77 C 11.

IV. Electrical resistivity e(T): Fig. 141 [87 B3].

Thermal conductivity x(T): Fig. 142 [87 B 31.

Additional literature [88 A 73.

0 50 100 150 200 250 K 300 500 mW cmK 100

I 300 Y

200

I I

0 50 100 150 200 250 K 300

I- T-

Fig. 141. LaCu,. Electrical resistivity e vs. tempera- Fig. 142. LaCu,. Thermal conductivity x vs. tempera-

ture [87 B 31. turc [87 B 33.

CeCu, I.

II.

III IV.

CaCus(D2,): hex Dk,-P6/mmm a = 5.138 A, c = 4.109 A, c/u =0.7997 [79 P 11.

Additional literature [61 D 1, 64 R 1, 71 B4, 82G 2, 87 B 81.

No magnetic ordering is observed down to 100 K [79 P 11.

Q= -14K,p,,,=2Slp,/Ce, ~o=137.4~10-“cm3mol-1, using x=C/(T-O)+,yo [79Pl].

p,zOS4p,/Ce at l.SK, by Arrott plot [87B8].

x-‘(T): Fig. 143 [79P 11.

Additional literature [83 C 4, 84 B 5, 87 W 2, 88 B 31.

An incommensurate structure at 1.5 K [87 B 83.

Electrical resistivity Q(T): Fig. 144 [87B 33.

Magnetic transition is observed at 3.9 K [87 B 33.

e,,,(T): Fig. 145 [87 B 31.

Specific heat

CJT vs. T: Fig. 146 [87 B 33.

C,,,IT and SmaF vs. T: Fig. 147 [87B 31.

C,,,[mJmol-‘K-‘]=C,-lOOT--0.82T3 [87B3].

AS=4.2 J mol-’ K-’ at the magnetic transition [87 B 33.

Thermal conductivity X((T): Fig. 148 [87B3].

AW. T vs. T: Fig. 149 [87 B 33.

W(= l/x) is the thermal resistivity. AW= W(CeCu,)- W(LaCu,) is the magnetic contribution to the electronic thermal resistivity.

Kaneko

Ref. p. 5011 2.6.2.1.1 Rare earth compounds: R,Cu, 61

Thermoelectric power Q(T): Fig. 150 [87 B 31.

NMR of ‘j3Cu

K(T), K(X): Fig. 151 [79P 11.

Additional literature [83 C 4, 84 B 5, 87 B 8, 87 W 2, 88 A 7, 88 B 31.

CeCu5

B” 1’

1’

0 200 400 600 K 800

T-

Fig. 143. CeCu,. Reciprocal magnetic mass suscepti- bility xi1 vs. temperature [79P 11.

I 6 4

&

2

0 1 10 102 K 103

T-

Fig. 145. CeCu,. Magnetic contribution to electrical resistivity, Q,,,, vs. temperature [87 B 31.

40

@m 30

I 20 ar

0 50 ¹⁰⁰ 150 200 250 ^K 300

T-

Fig. 144. CeCu,. Electrical resistivity Q vs. tempera- ture. Insert: details of the electrical resistivity near the magnetic transition at 3.9 K [87 B 31.

0 4 8 12 ^K

T-

Fig. 146. CeCu,. Specific heat divided by tempera- ture, Cdl; vs. temperature [Si B 31.

Landolt-Bhstein

New Series III/19el

Kaneko

62 2.6.2.1.1 Rare earth compounds: R,Cu, [Ref. p. 501

4

J ma!K?

I 3

J 50 mol K 4

I 3 -2 E

1

09 0 2 4 6 8 10 12 K 14

I-

Fig.

147. CeCu,. Magnetic contribution to specific heat divided by 7; C,,,IT, and entropy, S,,,, vs. tempera- ture [87 B 33.

-2

0 50 100 150 200 250 K 300 Fig. 150. CeCu,. Thermoelectric power Q vs. temper- ature [87 B 33.

300 mW

I cm 200

0 50 100 150 200 250 K 300 T-

Fig. 148. CeCu,. Thermal conductivitv x vs. tempera- ture [87B3]. _

3

I .102 cmK2 -iv-

O110

^K

T-

10 Fig. 149. CeCu,. AW.T vs. temperature, where A,W denotes the magnetic contribution to electrical and electronic thermal resistivity [87 B 33.

x9 -

0.238’ 2.5 5.0 7.5 10.0 W6cm3/g 15.0 I

% _CeCu5

, i 4-

0.230

I 0.226 k

0.222

^___I I I I I ^63cu I I

0 100 200 300 100 500 K 600

T-

Fig. 151. CeCu,. Knight shift K of 63Cu vs. tempera- ture and magnetic mass susceptibility X~ K is re- ferred to 63Cu in CuCl powder [79 P 11.

Kaneko

Ref. p. 5011 2.6.2.1 .l Rare earth compounds: R,Cu, 63

CaCu,(D2,): hex D&-P6/mmm a=5.125& c=4.106& c/a=0.8012 [75A I].

Additional literature [61 D 1, 71 B 41.

Van Vleck paramagnetic, nuclear ferromagnetic at low temperature:

Tc=40mK [75Al], 24mK [78Gl].

0 = lO(10) mK [75A 11, 24 mK [78 G 11.

rrs = 940 G cm3

mol-

’ at 5 mK [75 A I], 1000 G cm3 mol- ’ at 17 mK, with decreasing field after cooling in PrCu,

I.

II.

III.

IV.

At high temperatures above 30K:

O= 12K, ~~rr=3.36ua/Pr [75A I].

x(T): Fig. 152, xi’(T): Fig. 153 [75Al].

o(T): Fig. 154, a(H): Fig. 155 [75Al].

Additional literature [82 M 71.

Magnetic structure Nuclear ferromagnet

pPr=0.3(1) pa (magnetic momentllc axis) at about 10 mK [82 B 21.

Specific heat

C(T): Fig. 156 [75A 11.

60 kOe [78 G 11.

Schottky-type specific heat is observed.

Smearing out ofthe Schottky peak is due to the ferromagnetic exchange interaction which actually broadens the sharp crystal-field levels into bands of collective excitations.

C(T) under magnetic fields [75 A 11.

Additional literature [82 M 71.

1.2E cm3 a 1.00

t 0.75 G

0.50

0.2!

I-

XII PrCu,

l-

0 IO 20 30 K $0

Fig. 152. PrCu,. Low-field magnetic molar suscepti- bility x,,, vs. temperature, parallel (x1,) and perpendicular (xl) to the c axis of a single crystal, and for a polycry- stalline (j) sample. xl1 is deduced from x1 and 2 [75A I].

1

80 mol cm3 60

t -$LO

0 0.2 0.4 0.6 0.8 ^{K 1.0}

Fig. 153. PrCu,. Reciprocals of the difference between the observed and the Van Vleck magnetic susceptibility, xN1, vs. temperature for two applied magnetic fields [75A 11.

Land&-BGmstein

New Series III/19el Kaneko