Berlin 2015 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 95: Spintronics: Mobile Electrons and Holes (jointly with HL, MA)

TT 95.8: Talk

Thursday, March 19, 2015, 12:00–12:15, ER 164

Impurity band spin dynamics in GaAs directly above 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). The doping concentrations range from the MIT at 2*10¹⁶ cm⁻³, where extremely long spin lifetimes are experimentally observed [1], up to the merging of impurity and conduction band at 8*10¹⁶ cm⁻³, where for conduction band electrons the spin relaxation is typically dominated by the Dyakonov-Perel mechanism (DP). We conclude from our measurements that DP is also dominating the impurity band regime in slightly metallic samples. Furthermore the measurements show no indication of spin relaxation by hopping transport (HT) that has recently been predicted as the main mechanism of relaxation for the impurity band regime [2]. In contrast our measurements of the spin dynamics indicate 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).