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KR: Fachgruppe Kristallographie

KR 6: Poster: Crystallography in Materials Science

KR 6.4: Poster

Mittwoch, 16. März 2011, 15:00–17:30, P1

X-ray diffractometry of magnetic (Ga,Mn)As epitaxial layers — •Vaclav Holy¹, Xavier Marti¹, Lukas Horak¹, Vit Novak², and Tobias Schuelli³ — ¹Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 5, 121 16 Prague, Czech Republic — ²Insititute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnicka 10, 162 00 Prague, Czech Republic — ³ESRF, BP220, 38043 Grenoble, France

The magnetic Mn ions in (Ga,Mn)As epitaxial layers can be found in substitutional and two types of interstitial positions, however only the magnetic moments of the substitutional Mn ions can be ferromagnetically ordered, and the Mn interstitials are detrimental for the ordering. The determination of the density of Mn ions in different lattice positions is therefore an important task. We have determined the densities of Mn substitutional and interstitial ions in (Ga,Mn)As by high-resolution x-ray diffractometry both using a single wavelength, and by measuring the dependence of the diffracted intensity on the photon energy around the MnK absorption edge (anomalous diffraction). In the former method, the dependence of the lattice parameter of the (Ga,Mn)As alloy on the Mn densities must be known a-priori. The latter approach does not use the value of the lattice parameter, however it can be realized only by means of synchrotron radiation. We have used both methods for the study of the kinetics of out-diffusion of Mn interstitials from (Ga,Mn)As layers during post-growth annealing.