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HL: Fachverband Halbleiterphysik

HL 14: Spintronics: Transport and Theory

HL 14.2: Vortrag

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

Effects of lateral confinement on the spin dynamics in GaAs based two-dimensional electron systems — •Patrick Altmann¹, Makoto Kohda^2,1, Matthias P. Walser¹, Christian Reichl³, Werner Wegscheider³, and Gian Salis¹ — ¹IBM Research-Zurich, Saeumerstrasse 4, 8803 Rueschlikon, Switzerland — ²Department of Materials Science, Tohoku University, Sendai, Japan — ³Solid State Physics Laboratory, ETH Zurich, Zurich, Switzerland

In two-dimensional electron systems (2DES), the diffusive motion of the electrons leads to a precession of their spins because of spin-orbit interaction (SOI). We use time-resolved Kerr microscopy with spatial resolution below the spin-orbit length to directly visualize these precessions [1]. By this, the strength and anisotropy of the SOI are mapped out and the dominant dephasing mechanism and the diffusion constant are determined. We study the impact of lateral confinement on the spin dynamics in a GaAs based 2DES at 20 K. We observe a transition from a 2D spin mode to a quasi-1D mode in wire structures narrower than the spin-orbit length. While in the 2D case both linear and cubic terms of the SOI contribute to spin dephasing, in the 1D case only the cubic contribution remains limiting the spin dephasing time [2]. In the special case of fully anisotropic SOI, known as the persistent spin helix case, dephasing due to linear terms is already suppressed. Thus, wire confinement cannot further enhance the dephasing time, but the dilution of spins due to diffusion is reduced [3].

[1] Walser et al., Nat. Phys. 8, 757 (2012), [2] Altmann et al., accepted PRB, [3] Altmann et al., PRB 90, 201306(R) (2014)