Dresden 2011 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 44: Poster Session I

HL 44.6: Poster

Dienstag, 15. März 2011, 18:00–21:00, P3

Ab initio study of the phase-change magnetic material — Yan Li and •Riccardo Mazzarello — RWTH Aachen, Aachen, Germany

Phase-change materials based on chalcogenide alloys are of great technological importance due to their ability to undergo reversible and fast transitions between the amorphous and crystalline phases upon heating. This property, together with the strong optical and electronic contrast between the two phases, is exploited in rewritable optical discs (CDs, DVDs, Blu-Rays discs) and prototype non-volatile memories. Up to now, very few works have addressed the properties of chalcogenide phase change materials doped with magnetic impurities. In [1] it was shown that Ge_2Sb_2Te_5 doped with Fe exhibits phase-change behavior for not too large concentrations of Fe and that both the amorphous and the crystalline phases are ferromagnetic at low enough temperatures. Moreover, the two phases were found to have different ferromagnetic properties. However, very little is known about how magnetic impurities affect the atomic-scale mechanisms of the phase transition in these systems and also about the relationship between magnetism and structural properties. To shed light on these issues, we have investigated the structural, electronic and magnetic properties of amorphous and crystalline Ge_2Sb_2Te_5 doped with magnetic impurities from first principles. Models of the amorphous phases were generated by quenching from the melt by means of ab-initio molecular dynamics simulations. [1] W. Song, L. Shi, X. Miao and C. Chong, Adv. Mater. 20, 2394 (2008)