Dresden 2017 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 7: Spintronics I (joint session DS, HL, MA, TT, organized by HL)

TT 7.7: Talk

Monday, March 20, 2017, 11:30–11:45, POT 151

Control of spin helix symmetry in semiconductor quantum wells by crystal orientation — •Paul Wenk, Michael Kammermeier, and John Schliemann — Institute for Theoretical Physics, University of Regensburg, 93040 Regensburg, Germany

We investigate the possibility of spin-preserving symmetries due to the interplay of Rashba and Dresselhaus spin-orbit coupling in n-doped zinc-blende semiconductor quantum wells of general crystal orientation. It is shown that a conserved spin operator can be realized if and only if at least two growth-direction Miller indices agree in modulus. We determine the appropriate requirements on the axial symmetric Rashba and Dresselhaus contributions and discuss the impact of cubic Dresselhaus terms which break this symmetry. We observe that including the latter commonly inhibits a perfect realization of the persistent spin helix symmetry except for two specific directions, i.e., [110] and [111]. Furthermore, by analyzing the spectrum of the spin diffusion equation, we show that besides the cases of perfect spin-preserving symmetries, the spin of the long-lived homogeneous spin state relaxes about a factor 2 faster than for the helical spin state. To support experimental probing, we additionally provide analytical expressions for the weak (anti)localization correction and the characteristic shift of the magnetoconductivity minima [2] which show an imprint of the peculiar symmetry.

[1] M. Kammermeier et al., Phys. Rev. Lett. 117, 236801 (2016)

[2] K. Yoshizumi et al., Appl. Phys. Lett. 108, 132402 (2016).