Dresden 2011 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 30: Magnetic Semiconductors I

MA 30.6: Vortrag

Mittwoch, 16. März 2011, 12:15–12:30, HSZ 401

Spin-polarized hole transport in pulsed laser annealed Ge:Mn up to 30 K — •Danilo Bürger, Shengqiang Zhou, Manfred Helm, and Heidemarie Schmidt — Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden

The incorporation of transition metals dopants in semiconductors over their solubility limit is the main challenge for the fabrication of diluted ferromagnetic semiconductors. Low temperature molecular beam epitaxy (LT-MBE) is the standard technique for the fabrication of GaAs:Mn. Nevertheless, for Ge:Mn [1] the LT-MBE approach seems to be not successful to reach hole concentrations necessary for hole mediated ferromagnetism. On the other hand, pulsed laser annealing is a successful nonequilibrium annealing method and a promising technique for the fabrication of diluted Ge:Mn [2] and for III-V semiconductors, e.g. GaAs:Mn [3]. Recently we fabricated a ca. 100 nm thick Ge:Mn film by low temperature Mn-implantation followed by pulsed laser annealing and observed hole-mediated ferromagnetism up to 30 K via SQUID magnetization as well as magnetotransport measurements. The anisotropy of ferromagnetic Ge:Mn films will be discussed. Moreover, the Ge:Mn films show a remanent magnetization up to 220 K which is lower than the Curie temperature of typical Mn_xGe_y clusters [1]. The confirmation of spin-polarized hole transport up to 220 K becomes difficult because at elevated temperatures the conductivity is mainly determined by the Ge substrate. [1] M. Jamet et al., Nature. Mat. 5, 653 (2006) [2] Shengqiang Zhou et al., PRB 81, 165204 (2010) [3] Danilo Bürger et al., PRB 81, 115202 (2010)