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MA: Magnetismus

MA 20: Poster: Films(1-36) Transp(37-56) Ex.Bias(57-67) Spindyn(68-80) Micromag(81-95) Particle(96-109) Imag.+Surface(110-113) Spinelectr(114-122) Theory+Micromag(123-131) Spinstr+Aniso(132-142) MagMat(143-156) Meas(157,158) MolMag+Kondo(159-162) Postdead(163-)

MA 20.151: Poster

Dienstag, 28. März 2006, 15:15–19:15, P1

Identification of different Mn 3d electronic configurations in (GaMn)As ferromagnetic semiconductors and their influence on the magnetism — •Ruslan Ovsyannikov¹, F. Kronast¹, A. Vollmer¹, H. Dürr¹, W. Eberhardt¹, P. Imperia², D. Schmitz², G. Schott³, K. Brunner³, M. Sawicki³, and L. Molenkamp³ — ¹BESSY, Berlin — ²Hahn-Meitner-Institut, Berlin — ³University of Würzburg

We studied the hybridisation of Mn 3d and Ga/As valence orbitals in (Ga$_{1-x}$Mn$_x$)As films with x between 0.007 and 0.062 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.