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MA: Magnetismus
MA 26: Elektronentheorie
MA 26.8: Vortrag
Donnerstag, 27. März 2003, 17:00–17:15, HSZ/401
First principles studies of the magnetic ground state of bcc Eu — •Gustav Bihlmayer1, Philipp Kurz1, Stefan Blügel1, Ilja Turek2, and Josef Kudrnovský3 — 1Institut für Festkörperforschung, Forschungszentrum Jülich, 52425 Jülich — 2Institute of Physics of Materials, Academy of Sciences of the Czech Republik, Zizkova 22, CZ-616 62 Brno, Czech Republic — 3Institute of Physics, Academy of Sciences of the Czech Republik, Na Slovance 2, CZ-18221 Prague 8, Czech Republic
We present an ab-initio investigation of the ground state properties of bulk Eu. Based on density functional theory we apply the full-potential linearized augmented planewave method as realized in the FLEUR code extended to treat also noncollinear spin structures. Like in hcp Gd, the normal LSDA-formalism is insufficient to describe Eu correctly and an extension like the LDA+U model or a ’core’-like treatment of the 4f-electrons is required. The magnetic ground state of bcc Eu was found to be a spiral spin-density wave (SSDW) with a wavelength close to the experimentally observed value. We compare also with other SSDWs that can be stabilized experimentally by an applied magnetic field. We interpret the results with a classical Heisenberg model and estimate the Néel temperature by the MFA. Exchange interaction constants up to ten lattice constants were obtained from the Green-function tight-binding linear muffin-tin orbital method showing that even very long range interactions cannot be neglected and contribute significantly to the Néel temperature calculated in the RPA. Generally, the results are found to be in agreement with experimental data.