Přednášející: Ilja Turek (Institute of Physics of Materials, ASCR, Brno, and Faculty of Mathematics and Physics, Charles University, Praha )
Místo: Na Slovance, sál v přízemí
Jazyk: anglicky
Pořadatelé:
Oddělení teorie kondenzovaných látek
Abstract:
The talk reviews recent progress in ab initio theory of transport
properties of spin-polarized metallic systems in presence of
spin-orbit interaction. Our approach is based on evaluation of the
full conductivity tensor within the Kubo linear response theory
with impurity scattering due to chemical randomness. The alloy disorder
is taken into account by means of the coherent-potential
approximation (CPA) implemented in the tight-binding linear muffin-tin
orbital (TB-LMTO) method. The spin-orbit interaction is treated as an
on-site perturbation to the scalar-relativistic TB-LMTO Hamiltonian,
the velocity operators are reduced to intersite hopping elements, and
the CPA-vertex corrections to the conductivity tensor are included.
The developed theory is applied to cubic binary transition-metal alloys
FeCo (bcc), NiCo (fcc), NiFe (fcc) and NiMn (fcc) for which selected
concentration trends are discussed: (i) a strong deviation of the
isotropic resistivity from the Nordheim rule in FeCo alloys, (ii) a big
anisotropic magnetoresistance in NiCo and NiFe alloys, and (iii) the
change of sign of the anomalous Hall effect in Ni-based alloys.
Particular attention is paid to the dilute limit (bcc Fe, fcc Ni),
where the Kubo theory provides an alternative description of the anomalous
Hall conductivity of non-random magnets formulated recently in terms of
their band structure and the Berry curvature.
First results obtained for anisotropic magnetoresistance of Mn-doped
GaAs diluted ferromagnetic semiconductors will be presented and
discussed as well.
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