Regensburg 2007 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 10: Spinelectronics/Spininjection in Heterostructures

MA 10.15: Vortrag

Montag, 26. März 2007, 18:45–19:00, H23

A THEORETICAL STUDY ON HALFMETALLIC ANTIFERROMAGNETIC DILUTED MAGNETIC SEMICONDUCTORS FROM FIRST-PRINCIPLES AND STATISTICAL METHODS — •Lars Bergqvist and Peter Dederichs — Institute für Festkörperforschung, Forschungzentrum Jülich, D-525 25 Jülich, Germany

Based on electronic structure calculations and statistical methods we investigate a new class of materials for spintronic applications: halfmetallic antiferromagnetic diluted magnetic semiconductors (HMAF-DMS). As shown recently by Ogura and Akai these DMS systems contain equal amounts of low-valent and high-valent transition metal impurities, such that their local moments exactly compensate each other. We present ab-initio calculations by the KKR-CPA method and by the PAW-supercell methods, using the LDA and LDA+U methods, and show that quite a few halfmetallic antiferromagnets should exist. Our calculations demonstrate, that the exchange coupling parameters in these systems are dominated by a strong antiferromagnetic interaction between the two impurities. The Neel temperatures are calculated by Monte Carlo simulations and in mean field approximation. It is shown that the latter method strongly overestimates the critical temperatures and that the more realistic values obtained by Monte Carlo are rather low.