Dresden 2009 – scientific programme

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MA: Fachverband Magnetismus

MA 13: Poster Ia: Electron Theory (1); Magnetic Imaging (2,3); Thin Films (4-25); MSMA (26-33); Magn. Semiconductors (34-42); Magn. Half Metals and Oxides (43-60)

MA 13.35: Poster

Tuesday, March 24, 2009, 10:15–13:00, P1A

Effects of thermal treatment on the electronic structure of Ga_1−xMn_xAs — •Benjamin Schmid¹, Dominic Fertig¹, Sebastian Engelbrecht¹, Michael Sing¹, Lars Ebel², Charles Gould², Karl Brunner², Laurens W. Molenkamp², and Ralph Claessen² — ¹Experimentelle Physik IV, Universität Würzburg, Würzburg, Germany — ²Experimentelle Physik III, Universität Würzburg, Würzburg, Germany

Despite intense research over the last decade the electronic structure of diluted magnetic semiconductors, especially the prototypical (Ga,Mn)As system, remains subject of controversial discussions. The interplay of substitutional and interstitial Mn and the possible exsistence of a Mn-related impurity band are two major issues. The situation is further complicated by post-growth treatments required for the improvement of the transport and magnetic properties. Photoemission spectroscopy (PES) is an outstanding tool for the investigation of electronic properties of solids, both in regard to the chemical state of ions and the conduction electrons near the Fermi-energy.
We present a detailed study of changes in the electronic structure of Ga_1−xMn_xAs upon various sample treatments. Effects of ex-situ and in-situ thermal treatment as well as wet-chemical etching and ion-sputtering are discussed on basis of the Mn 2p-doublet and the density of states in the vicinity of the Fermi-energy. The results are backed by complementary tools, i.e., low-energy electron diffraction (LEED) and atomic force/scaning tunneling microscopy (AFM/STM).