Regensburg 2007 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 22: FV intern Symposium: "Heusler Alloys"
Invited Talks Kübler/Yamamoto/Inomata/Silvia Picozzi

MA 22.4: Hauptvortrag

Donnerstag, 29. März 2007, 11:45–12:15, H10

First-principles study of ferromagnetic Heusler alloys: an overview — •Silvia Picozzi — CNR-INFM CASTI Regional Lab, 67010 L'Aquila (Italy)

On the basis of ab-initio results, I will review several aspects of ferromagnetic Co2MnX (X = Si, Ge and Sn) Heusler alloys, predicted to be half-metallic and, as such, promising candidates for spin-injection purposes. In particular, I will focus on:

i) Bulk magneto-optical properties: after a brief review of their electronic and magnetic properties, a careful analysis of magneto-optical spectra, in comparison with experiments, will be presented.

ii) Polarization reduction mechanisms. Our results show that in Heusler compounds a) intrinsic point-defects can be detrimental for half-metallicity and b) when joined to mainstream semiconductors, the presence of interface states at the Fermi level can degrade their performances. In particular, I will focus on Co2MnSi and Co2MnGe, in the presence of intrinsic defects (such as stoichiometric atomic swaps as well as non-stoichiometric antisites) and interfaced with GaAs and Ge. Antisites, due to their low formation energies, can easily occur, consistently with experiments; however, only Co antisites give rise to defect-states at the Fermi level. As for the [001]-ordered interfaces, the strong hybridization at the junction gives rise to broad interface states which locally destroy half-metallicity. Finally, in the context of multiferroic tunnel junctions, preliminary results for Heuslers interfaced with ferroelectrics will also be presented.