Fyzikální ústav Akademie věd ČR

Seminář Úterý, 06.11.2012 15:00 - 16:00

Přednášející: Ilja Turek (Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Prague)
Místo: Na Slovance, přednáškový sál v přízemí
Jazyk: anglicky
Pořadatelé: Oddělení teorie kondenzovaných látek

Abstract: The seminar reviews the formulation and recent results of a fully relativistic first-principles theory of metallic ferromagnetic systems. The theory is based on the all- electron tight-binding linear muffin-tin orbital (LMTO) method and the coherent potential approximation (CPA). Particular attention will be devoted to the spin and orbital magnetic moments, total energies, and transport properties.
As an example, the properties of random Fe-Co alloys in tetragonal structures will be presented and discussed. These alloys were predicted to exhibit a giant uniaxial magnetic anisotropy energy (MAE) which would make them a promising material for magnetic recording. It will be shown that a correct treatment of the chemical randomness present in real samples reduces dramatically the MAE; the effect of a perfect and partial atomic long-range order on the MAE will be briefly discussed as well.
In the last part, the anisotropy of static transport properties of these alloys will be discussed with a focus on an orientation dependence of the anomalous Hall conductivity (AHC). We have found that the AHC values for the magnetization direction pointing along the tetragonal a and c axes can differ nearly three times for certain tetragonal distortions and alloy compositions. This anisotropy exceeds that calculated for the pure tetragonal Fe and Co metals and it seems to be surprisingly stable with respect to the alloy disorder.
(*) in collaboration with J. Kudrnovský, V. Drchal and K. Carva