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TT: Fachverband Tiefe Temperaturen

TT 29: Transport: Quantum Dots, Wires, Point Contacts 3 (jointly with HL)

TT 29.1: Vortrag

Dienstag, 12. März 2013, 09:30–09:45, H20

Theory of Spin Relaxation in Two-Electron Laterally Coupled GaAs and Si Quantum Dots — •Martin Raith¹, Peter Stano^2,3, and Jaroslav Fabian¹ — ¹Institute for Theoretical Physics, University of Regensburg, 93040 Regensburg, Germany — ²Department of Physics, University of Basel, 4056 Basel, Switzerland — ³Institute of Physics, Slovak Academy of Sciences, 845 11 Bratislava, Slovakia

We present quantitative results of the phonon-induced spin relaxation in two-electron lateral double quantum dots. Both spin-orbit coupling and hyperfine coupling are taken into account. Our analysis of GaAs [1] and silicon [2] based dots includes the variation of the electric field (detuning), the exchange coupling, and the magnetic field strength and orientation. We find that even in strong magnetic fields, the hyperfine coupling can dominate the relaxation rate of the unpolarized triplet in a detuned GaAs double dot. This feature is absent in silicon (we assume a ²⁹Si abundance of 4.7%). Where the spin-orbit coupling dominates, the rate is strongly anisotropic and its maxima and minima are generated by an in-plane magnetic field either parallel or perpendicular to the dots’ alignment dependent on specifics, such as spectral (anti-) crossings (spin hot spots), or the detuning strength. We emphasize the differences between GaAs and Si based dots. This work marks a crucial step toward the realization of two-electron semiconductor qubits.
This work is supported by the DFG under grant SPP 1285.
[1] M. Raith et. al., PRL 108, 246602 (2012)
M. Raith et. al., arXiv:1206.6906