Regensburg 2004 – wissenschaftliches Programm

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MA: Magnetismus

MA 20: Magnetische dünne Schichten II

MA 20.7: Vortrag

Donnerstag, 11. März 2004, 11:45–12:00, H10

Spin polarization of single-crystalline Co₂MnSi films grown by PLD on GaAs(001) — •W. Wang, W. Kuch, L. Chelaru, J. Wang, Y. Lu, J. Barthel, M. Przybylski, and J. Kirschner — Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle

Recent theoretical calculations have shown that the full-Heusler alloy Co₂MnSi is a promising candidate to be a half-metallic ferromagnet. In this contribution we report on the growth, magnetic and electronic characterization of single crystalline Co₂MnSi thin films deposited by Pulsed Laser Deposition (PLD) on GaAs(001) substrates. In situ Reflection High Energy Electron Diffraction (RHEED) and Auger spectroscopy confirmed the high-quality growth (in particular at 450K growth temperatures) and stoichiometry. Spin-resolved photoemission measurements at BESSY-II of the single-crystal Co₂MnSi films reveal spin-resolved density of states that are in qualitative agreement with recent band structure calculations. However, the spin polarization of photoelectrons close to the Fermi level is found to be at most 25%, in contrast to the predicted half-metallic behavior. Moreover, the magnetic moments we obtained by sum rule analysis of x-ray magnetic circular dichroism (XMCD) measurements of thin Co₂MnSi films are lower in comparison to what is predicted theoretically. We suggest that these discrepancies may be attributed to a non-magnetic surface region and/or partial chemical disorder in the Co₂MnSi lattice.