Regensburg 2007 – scientific programme

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MA: Fachverband Magnetismus

MA 10: Spinelectronics/Spininjection in Heterostructures

MA 10.11: Talk

Monday, March 26, 2007, 17:45–18:00, H23

Investigation of different Mn states in Ga_1−xMn_xAs by HX-PES — •Benjamin Schmid¹, Andreas Müller¹, Michael Sing¹, Jan Wenisch², Karl Brunner², Laurens Molenkamp², Wolfgang Drube³, and Ralph Claessen¹ — ¹Lehrstuhl für Experimentelle Physik IV, Universität Würzburg, Germany — ²Lehrstuhl für Experimentelle Physik III, Universität Würzburg, Germany — ³HASYLAB, DESY, Hamburg, Germany

The complex interplay of ferromagnetic coupling and compensating effects in the diluted magnetic semiconductor (DMS) Ga_1−xMn_xAs (x =2−8 %) is currently under intense discussion. Both the Curie temperature T_C and the carrier concentration induced by manganese hosted in the lattice at regular sites are reduced by interstiatial Mn. In order to minimize those defects for applications and investigate possible changes in the electronic structure under various chemical and physical surface treatments we performed bulk sensitive hard X-ray photoemission spectroscopy (HX-PES) at hν=4500 eV. The enlarged inelastic mean free path of the photoelectrons provides an information depth of up to 5 nm. A comparison with the related system manganese arsenid, untreated and oxidized under controlled conditions, allows a direct observation of fingerprints associated with different valencies in the core levels.