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Magnetic anisotropy in the cubic Laves REFe2 intermetallic compounds

Magnetic anisotropy in the cubic Laves REFe2 intermetallic compounds
Magnetic anisotropy in the cubic Laves REFe2 intermetallic compounds
In the past, the Callen–Callen (1965 Phys. Rev. 139 A455–71; 1966 J. Phys. Chem. Solids 27 1271–85) model has been highly successful in explaining the origin and temperature dependence of the magneto-crystalline anisotropy in many magnetic compounds. Yet, despite their high ordering temperatures of ~650 K, the Callen–Callen model has proved insufficient for the REFe2 compounds. In this paper, we show that it is possible to replicate the values of the phenomenological parameters K1, K2, and K3 given by Atzmony and Dariel (1976 Phys. Rev. B 13 4006–14), by extending the Callen–Callen model to second order in HCF. In particular, explanations are provided for (i) the unexpected changes in sign of K1 and K2 in HoFe2 and DyFe2, respectively, and (ii) the origin and behaviour of the K3 term. In addition, it is demonstrated that higher order terms are required, and that K4 exceeds K3 at low temperatures. Revised estimates of K1, K2, K3, K4, and K5 are given. Finally, an alternative 'multipolar' approach to the problem of magnetic anisotropy is also provided. It is shown that the latter confers significant advantages over the older phenomenological method. In particular, all the multipolar coefficients (\tilde {K}_N , N = 4, 6, 8, 10, 12) decrease monotonically with increasing temperature, with \tilde {K}_N decreasing faster than \tilde {K}_{N-2} etc. These observations are in accord with expectations based on the original Callen–Callen model.
0953-8984
459-478
Martin, K.N.
c53d0004-4655-40e9-aa05-563f3a9602c4
de Groot, P.A.J.
98c21141-cf90-4e5c-8f2b-d2aae8efb84d
Rainford, B.D.
a57f1153-bbba-49a3-bffc-0d96087156a0
Wang, K.
2b399d1b-c3f1-4863-b78b-dd9135ef7532
Bowden, G.J.
f73a1c01-4d38-4170-bf30-9ebfa4283807
Zimmermann, J.P.
b4047fb7-cba4-4777-9847-18061e78706e
Fangohr, H.
9b7cfab9-d5dc-45dc-947c-2eba5c81a160
Martin, K.N.
c53d0004-4655-40e9-aa05-563f3a9602c4
de Groot, P.A.J.
98c21141-cf90-4e5c-8f2b-d2aae8efb84d
Rainford, B.D.
a57f1153-bbba-49a3-bffc-0d96087156a0
Wang, K.
2b399d1b-c3f1-4863-b78b-dd9135ef7532
Bowden, G.J.
f73a1c01-4d38-4170-bf30-9ebfa4283807
Zimmermann, J.P.
b4047fb7-cba4-4777-9847-18061e78706e
Fangohr, H.
9b7cfab9-d5dc-45dc-947c-2eba5c81a160

Martin, K.N., de Groot, P.A.J., Rainford, B.D., Wang, K., Bowden, G.J., Zimmermann, J.P. and Fangohr, H. (2006) Magnetic anisotropy in the cubic Laves REFe2 intermetallic compounds. Journal of Physics: Condensed Matter, 18 (2), 459-478. (doi:10.1088/0953-8984/18/2/009).

Record type: Article

Abstract

In the past, the Callen–Callen (1965 Phys. Rev. 139 A455–71; 1966 J. Phys. Chem. Solids 27 1271–85) model has been highly successful in explaining the origin and temperature dependence of the magneto-crystalline anisotropy in many magnetic compounds. Yet, despite their high ordering temperatures of ~650 K, the Callen–Callen model has proved insufficient for the REFe2 compounds. In this paper, we show that it is possible to replicate the values of the phenomenological parameters K1, K2, and K3 given by Atzmony and Dariel (1976 Phys. Rev. B 13 4006–14), by extending the Callen–Callen model to second order in HCF. In particular, explanations are provided for (i) the unexpected changes in sign of K1 and K2 in HoFe2 and DyFe2, respectively, and (ii) the origin and behaviour of the K3 term. In addition, it is demonstrated that higher order terms are required, and that K4 exceeds K3 at low temperatures. Revised estimates of K1, K2, K3, K4, and K5 are given. Finally, an alternative 'multipolar' approach to the problem of magnetic anisotropy is also provided. It is shown that the latter confers significant advantages over the older phenomenological method. In particular, all the multipolar coefficients (\tilde {K}_N , N = 4, 6, 8, 10, 12) decrease monotonically with increasing temperature, with \tilde {K}_N decreasing faster than \tilde {K}_{N-2} etc. These observations are in accord with expectations based on the original Callen–Callen model.

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Published date: 14 December 2006

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Local EPrints ID: 57453
URI: https://eprints.soton.ac.uk/id/eprint/57453
ISSN: 0953-8984
PURE UUID: eaccf4b6-8157-47e6-ab26-3a29c5ea2766

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Date deposited: 13 Aug 2008
Last modified: 13 Mar 2019 20:34

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Contributors

Author: K.N. Martin
Author: P.A.J. de Groot
Author: B.D. Rainford
Author: K. Wang
Author: G.J. Bowden
Author: J.P. Zimmermann
Author: H. Fangohr

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