Regensburg 2004 – wissenschaftliches Programm
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MA: Magnetismus
MA 31: Spinelektronik
MA 31.4: Vortrag
Freitag, 12. März 2004, 11:30–11:45, H22
Magnetic Circular Dichroism Study of Ferromagnetic GaMnN — •J. Keller1, A. Dohmen1, B. Beschoten1, G. Güntherodt1, S. Dhar2, O. Brandt2, A. Trampert2, L. Däweritz2, K.J. Friedland2, and K.H. Ploog2 — 12. Physikalisches Institut, RWTH Aachen, D-52056 — 2Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, D-10117 Berlin
Because of possible applications in spinelectronics, there is a renewed interest in diluted magnetic semiconductors. We have investigated GaN thin films doped with Mn [1]. Depending on the Mn concentration, the GaMnN films are paramagnetic or ferromagnetic. At low temperatures, all samples exhibit spin-glass like behavior. Structural characterization reveals that Mn-rich clusters are formed in the ferromagnetic samples, while the paramagnetic samples form a uniform alloy of (Ga,Mn)N. To further investigate the magnetic properties of these samples, we have performed magnetic circular dichroism (MCD) measurements in the visible spectral range of light. The MCD spectra of all samples show peak structures around 1.5eV and a very broad structure around 2.5eV with a superimposed substructure. In addition, the paramagnetic samples exhibit a peak around 1.8eV. According to [2], the peak at 1.5eV can be assigned to an excited neutral acceptor state and the peak at 1.8eV to a transition from Mn3+ to Mn2+, while according to [3] the peak at 1.5eV corresponds to the charged acceptor state. Supported by BMBF/FKZ01BM160.
[1] S. Dhar et al., Appl. Phys. Lett. 82, 2077 (2003)
[2] T. Graf et al., Appl. Phys. Lett. 81, 5159 (2002)
[3] R.Y. Korotkov et al., Appl. Phys. Lett. 80, 1731 (2002)