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MA: Magnetismus

MA 4: Oberfl
ächenmagnetismus

MA 4.12: Vortrag

Montag, 8. März 2004, 13:00–13:15, H22

Electronic structure versus spin polarization in NiMnSb — •Jürgen Braun, Hristo Kolev, Georgi Rangelov, and Markus Donath — Physikalisches Institut, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm Str. 10, 48149 Münster

Half-metallic semi Heusler alloys like NiMnSb have been ascribed promising materials for spintronic devices, because of a theoretically predicted high spin polarization at the Fermi level. Unfortunately, from our spin-resolved Appearance Potential Spectroscopy (SRAPS) measurements an unexpected low spin polarization was observed. This result is in agreement with experimental findings from other groups but yet not understood. To investigate the physical origin of this discrepancy we performed a quantitative theoretical analysis of the experimental data. Using a fully relativistic theory of SRAPS, which describes the measured spectra as the self-convolution of the matrix-element weighted, orbitally-resolved unoccupied density of states, we are able to present a quantitative explanation for the small spin polarization experimentally found in (semi) Heusler alloys.