Regensburg 2004 – scientific programme

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HL: Halbleiterphysik

HL 35: Symposium Ferromagnetische Halbleiter

HL 35.5: Talk

Thursday, March 11, 2004, 12:15–12:45, H15

Hydrogen-control of ferromagnetism in Ga_1−xMn_xAs thin films — •Sebastian T. B. Goennenwein^1,2, Hans Huebl¹, Thomas A. Wassner¹, Christoph Bihler¹, Martin Stutzmann¹, Achim Koeder³, Wladimir Schoch³, Andreas Waag³, and Martin S. Brandt¹ — ¹Walter Schottky Institut, Technische Universität München, Am Coulombwall 3, D-85748 Garching, Germany — ²Department of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands — ³Abteilung Halbleiterphysik, Universität Ulm, D-89069 Ulm, Germany

Dilute magnetic semiconductors (DMS) are investigated vigorously at present, as these materials combine magnetic ordering with the versatile properties of semiconductors. In the prototype DMS Ga_1−xMn_xAs, which we discuss here, the ferromagnetic exchange interaction between the localized Mn magnetic moments is mediated by itinerant holes, so that the density of both Mn moments and of holes is crucial for the magnetism. We show that upon exposure to a remote DC deuterium plasma, the hole density p in Ga_1−xMn_xAs thin films with x=0.037 and x=0.051 can be reduced by several orders of magnitude. At the same time, the density of Mn magnetic moments is not significantly affected by the plasma treatment. Nevertheless, the ferromagnetism clearly present in the as-grown samples has vanished after the deuteration. We analyze the effect of the deuteration in detail, comparing the results of secondary ion mass spectroscopy, DC magnetization, and Fourier-transform infra-red optical experiments. We also address possible applications of this post-growth ”hydrogen-control” of the magnetic properties of Ga_1−xMn_xAs.