Regensburg 2016 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 4: Spintronics: Nanostructures and Optics

HL 4.9: Vortrag

Montag, 7. März 2016, 12:00–12:15, H13

Impurity dominated spin dynamics in GaAs in the vicinity of the metal-to-insulator transition — •Jan Gerrit Lonnemann¹, Eddy Patrick Rugeramigabo², Jens Hübner¹, and Michael Oestreich¹ — ¹Institute for Solid State Physics, Leibniz Universität Hannover, Appelstr. 2, D-30167 Hannover, Germany — ²Laboratory of Nano and Quantum Engineering, Leibniz Universität Hannover, Schneiderberg 39, D-30167 Hannover, Germany

Several theoretical works treat the spin dynamics in zinc-blende semiconductors. We present extremely low excitation Hanle depolarization measurements on well characterized n-doped MBE grown GaAs in the vicinity of the metal-to-insulator transition (MIT). This doping concentration regime is of special interest because around the MIT at 2*10¹⁶ cm⁻³ extremely long spin lifetimes are experimentally observed [1]. Spin relaxation in this regime is dominated by the impurity states because the merging of impurity and conduction band does not take place below 8*10¹⁶ cm⁻³. We conclude from our measurements that the well known D’yakonov Perel mechanism is dominating in slightly metallic samples. Furthermore there is no evidence of spin relaxation by hopping transport (HT) above the MIT that has been predicted as the main mechanism of relaxation for the impurity band regime [2]. In contrast our measurements show a metal-like behavior of the electrons in the impurity band.

[1] M. Römer et al.; Phys. Rev. B, 81, 075216 (2010).

[2] G.A. Intronati et al.; Phys. Rev. Lett., 108, 016601 (2012).