Erbium

POH -

2.1.3.11 Erbium

conical ferro

quasi - sinusoidal

antiphase variation para domain

0 19.5 53 K 85

T-

Fig. 335. Ordered spin structures observed by neutron diffraction for Er [74 H 21. See also [64 F 1, 61 G I].

I

²⁰

T-

30 40 K

T-

O

6

50

Fig. 336. (a) Integrated neutron scattering intensities of the (002) nuclear reflection of Er and its first-order satellite (002)- as a function of temperature. Solid and open symbols refer to increasing and decreasing temperature, respectively. The presence of (002)’ satellites at tempera- tures below TH = 52.4 K are attributed to the basal-plane moment ordering in a spiral with wavevector parallel to the c axis. (b) Integrated neutron scattering intensity of higher-order satellites of (000) and (002) nuclear reflec- tions vs. temperature [74 H 21.

Land&-BBmstein

New Series III/19dl

H. Drulis, M. Drulis

166 2.1.3.11 Er: figures [Ref. p. 183

T

20 LO 60 80 K 100

Er I I

20 LO 60 K

T-

Fig 338. Integrated neutron scattering intcnsitics of the higher-order harmonics ofthe c axis magnetic moment vs.

temperature for Eras temperature is decreased below the N&l point. Solid and open symbols refer to increasing and decreasing temperature, respectively. The 31d and Sh harmonics arc rcfcrred to the scale on the right-hand side, while the 7’” through the 171h harmonics are referred to the scale on the left-hand side. The appearance of higher- order satellites indicates that the c axis magnetic moment structure deviates from a purely sinusoidal modulation [74 H 21.

Fig. 337. Integrated neutron scattering intensity of the (100) nuclear reflection ofan Er single crystal and its first- order satellites (100)’ vs. temperature. Solid and open symbols refer to increasing and decreasing temperature, respectively. Observation oflirst-order magnetic satellites of all but the (001) nuclear reflections indicates that the c axis magnetic moment of Er orders at r84K in a sinusoidally modulated magnetic structure with wavevec- tor parallel to the c axis. A N&l temperature Th’ of 84.4 K was obtained by extrapolating the intensities of the tirst- order satellites. Below a temperature Tc of approximately 18 K an additional contribution to the intensity of all but the (001) nuclear reflections is observed. This implies ferromagnetic alignment of the c axis magnetic moment [74 H 21.

Fig. 339. Amplitudes of the nlh-order harmonics of (a) the c axis magnetic moment structure, py’, and (b) the basal- plane magnetic moment structure, p;), for Er at T> T,. I For T < Tc the c axis magnetic moment, p,,, and the basal- plane moments, pI, of the conical magnetic structure are shown. Solid and open symbols refer to increasing and decreasing temperature, respectively [74 H 23.

H. Drulis, M. Drulis

Land&Bknstein New Series 111/19dl

Ref.

p.

1831 2.1.3.11 Er: figures 167

5

ps Er

0 10 20 30 40 50 60 70 K 80

T-

Fig. 340. Basal-plane amplitudes of the magnetization waves in H = 0 and 20 kOe as a function of temperature for a single crystal of Er. The Yd and Sh harmonic amplitudes are magnified by a factor of two [74A I].

IO

PE

E

I E a’

-- la= I

i

[

I- I I_

I- ,- ,-

l-

-0 IO 20 30 40 50

T-

60

Fig. 341. c-axial amplitudes, p\i), of the magnetization waves up to the Ilth harmonic as a function of tem- perature for a single crystal of Er at T> T,. These data are uninfluenced by H = 0.. .20 kOe 11 a or b. For T < Tc the c axis magnetic moment, p,,, and its experimental ambigu- ity are shown for the conical magnetic structure [74A I].

Land&-Biimstein

New Series III/19dl

H. Drulis, M. Drulis

168 2.1.3.11 Er: figures [Ref. p. 183

0 10 20 30 40 50 60 70 80 K 90

T-

Fig. 342. First-order wavelengths of the magnetic mo- mcnt modulating waves in a single crystal of Er metal in H =0 and 20 kOe. (a) (001) data, (b) (hO0) and (hh0) data [I4 A 11.

0.30 Fr 0.29 - I-’

I

^{0.28 0.27}

N e 2 0.26

0.25

o decreasing temperature 0.21 -

r, T" TN

0.23 _

0 15 30 L5 60 75 K 90

T-

Fig. 343. Temperature dependence of the magnetic periodicity, Q, in Er, as obtained from single-crystal neutron diffraction results. Arrows show main transition temperatures in Er. Circles and triangles refer to data of different authors. From roughly 24 to 18K the spatial period of magnetically periodic ordering is exactly equal to 4c or 8 magnetic layers. The inflection point at 33 K could be associated with a commensurate structure of 15 magnetic layers [74 H 23.

H. Drulis, M. Drulis

Landolt-BGmstein New Series 111/19dl

Ref.

p.

1831 2.1.3.11 Er: figures

175 Gcm3

9 150 125

I 100 b

75

0 IO 20 30 40 50 60 70 kOe

H-

Fig. 344. Curves of the magnetization, cr vs. a magnetic field, H, applied along the a axis at different temperatures in Er. The discontinuity at a critical field Hcl, equal to 18 kOe for temperatures up to 18 K, corresponds to the conical structure domain at zero applied field. At H,, erbium undergoes a transition to the ferromagnetic structure with the magnetic moment making an angle 0=27” with c axis [69F I].

Gzl I

_5-

- 3

9

151 I-

125

I 100 Is

75

50

25

L 0

Er

Hllb

^_ LU 30 40 50 kOe 60

H-

Fig. 345. Curves of the magnetization, (r, vs. a magnetic field, H, applied along the b axis at different temperatures in Er. The characteristic discontinuity at a critical field H, equal to 18 kOe shows almost no temperature de- pendence up to 20 K [69 F I].

Land&-Bhmstein

New Series III/l9dl

H. Drulis, M. Drulis

170 2.1.3.11 Er:

figures

[Ref.

p.

183

200

I 150 b

U 1u 1U 30 40 50 kOe 60

H-

Fig. 346. Curves of the magnetization, (T vs. a magnetic field, H, applied along the c axis at different temperatures in Er. Below 20K erbium is ferromagnetic with extra- polated magnetic moment of 8.15 uJEr at 0 K. From 20 K to the N&l temperature there is only one critical field, H,, corresponding to the transition from the longitudinal oscillation to the ferromagnetic structure along the c axis.

The critical tield, H,, which is zero below 20 K, increases with temperature as is shown in Fig. 347 [69 F 11.

0

0 20 20 LO LO 60 60 K K

l- 25

kOe 20

Fig. 347. Critical magnetic fields along the c axis required to transform the quasi antiphasc domain configuration to the conical ferromagnetic state of Er vs. temperature.

Data above ~55 K (solid circles) correspond to the transition field in the sinusoidal magnetic moment region found by pulse field mcasuremcnts [69 F 1).

300 Gcm3

9 250

b ¹⁵⁰ 100

K-Er ! I, I, c

11 I=l.ZK ( I$

6.0 45 L I

a"

0

^{30 60 90} 120 kOe 150

Fig. 348. Magnetization curves of Er at 4.2 K vs. magnetic tield, H, up to ISOkOe along the a, 6, and c axes. The magnctimtion curves for the a and b axes reach the saturation value of the Er magnetic moment at x 150 kOe [68X2].