Dresden 2003 – wissenschaftliches Programm

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MA: Magnetismus

MA 26: Elektronentheorie

MA 26.7: Vortrag

Donnerstag, 27. März 2003, 16:45–17:00, HSZ/401

Electronic Structure and Magnetostriction in Bulk Gadolinium — •Ulrike Nitzsche¹, Manuel Richter¹, Igor Chaplygin², Klaus Koepernik¹, Ingo Opahle¹, and Helmut Eschrig¹ — ¹IFW Dresden, P.O.B. 270016, D-01171 Dresden, Germany — ²TU Chemnitz, D-09107 Chemnitz, Germany

Both Gadolinium and its compounds exhibit large spontaneous magnetostriction effects, comparable in magnitude with single-ion contributions in other rare-earth systems [1]. We have investigated the anisotropic magnetostriction of elemental hcp Gd metal in two different approximations to density functional theory, the local spin density approximation (LSDA) and the so-called LSDA+U. The simplest possible model for the paramagnetic state (PM) with large persisting 4f-moments is a static (001) antiferromagnetic (AFM) arrangement. Using this model, we find 1.5% volume magnetostriction in LSDA and 2% in LSDA+U. Both calculations include a c/a optimization. The result is to be compared with an experimental value of 0.5% volume magnetostriction. A larger value is expected for our simple AFM model, as the PM spin arrangement should be intermediate between AFM and FM. Other models for the PM state are tested: a disordered AFM state, treated in the coherent potential approximation, and a cluster AFM state. The calculations have been carried out with the scalar relativistic full-potential local-orbital minimum basis (FPLO) scheme.

[1] Lindbaum, A., and M. Rotter, 2002, in: Handbook of Magnetic Materials, Vol. 14, ed. K.H.J. Buschow (Elsevier Science B.V.), p. 307.