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SYAI: Symposium Ab-Initio Approaches to Excitations in Condensed Matter

SYAI 1: Invited Talks

SYAI 1.3: Hauptvortrag

Donnerstag, 26. März 2009, 16:00–16:30, SCH 251

LDA+DMFT approach to excitations spectrum in Half-Metallic Ferromagnets — •Alexander Lichtenstein — Institute of Theoretical Physics, University of Hamburg, Germany

We present a realistic many-body approach to excitation spectrum in the itinerant magnetic systems. The Half-Metallic Ferromagnets are an important class of itinerant electron materials because of their potential for spin-electronics. The Heusler alloy NiMnSb was the first material predicted to be a Half-Metallic Ferromagnet(HFM)in the framework of the Local Density Approximation (LDA) with the Fermi level in the gap for one of the spin directions. We study the effects of strong correlation between spin and charge degrees of freedom in NiMnSb within the Dynamical Mean Field Theory (DMFT). Based on LDA+DMFT electronic structure calculations we present the first ab-initio evidence for the existence of non-quasiparticle states lying in the gap of the minority spin channel just above the Fermi level [1]. We discuss a general and exact scheme to spin-excitation spectrum in the magnetic nanosystems and investigate the temperature dependance of demagnetization in Half-Metallic Ferromagnets.

[1] M. I. Katsnelson, V. Yu. Irkhin, L. Chioncel, A. I. Lichtenstein, and R. A. de Groot, "Half-metallic ferromagnets: From band structure to many-body effects", Rev. Mod. Phys. 80, 315 (2008).