Berlin 2005 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 17: Poster Ib

HL 17.69: Poster

Freitag, 4. März 2005, 16:30–19:00, Poster TU F

Relationship between Mn 3d electron hybridization and magnetic order in (GaMn)As dilute ferromagnetic semiconductors — •F. Kronast¹, R. Osyannikov¹, A. Vollmer¹, H.A. Dürr¹, W. Eberhardt¹, P. Imperia², D. Schmitz², G. Schott³, K. Brunner³, M. Sawicki⁴, and L. Molenkamp³ — ¹Bessy GmbH , Albert-Einstein-Str.15, 10439 Berlin — ²Hahn-Meitner-Institut, Albert-Einstein-Str.15, 10439 Berlin — ³Universität Würzburg, am Hubland, D-97074 Würzburg — ⁴Institute of Physics, Polish Academy of Sciences, Warszawa, Poland

The hybridization of Mn 3d and Ga/As valence orbitals in (Ga_1−xMn_x)As films with x between 0.007 and 0.062 was studied using x-ray absorption techniques. The signature of Mn acceptor states responsible for long-range ferromagnetic order can be identified with x-ray magnetic circular dichroism at all Mn concentrations. An additional magnetically dead Mn species with a reduced number of 3d electrons is observed for 0.062 Mn. We provide evidence that this is due to Mn-Mn nearest neighbor pairs which bind valence holes and ultimately limit the size of the magnetic ordering temperature.