Martin Raith, Peter Stano, Jaroslav Fabian
Highly accurate numerical results of phonon-induced two-electron spin relaxation in silicon double quantum dots are presented. The relaxation, enabled by spin-orbit coupling and the nuclei of 29Si (natural or purified abundance), are investigated for all relevant parameter regimes, the interdot coupling, the magnetic field magnitude and orientation, and the detuning. We calculate all relaxation rates for zero and finite temperatures (100 mK), concluding that all findings for zero temperature qualitatively remain valid also for 100 mK. We confirm the same anisotropic switch of the axis of prolonged spin lifetime with varying detuning as recently predicted in GaAs. However, there is a striking difference compared to the GaAs counterpart. In silicon, the hyperfine-induced relaxation rate is negligible in all cases we studied-even for natural silicon. The spin-orbit coupling, although weak, is the dominant contribution, yielding anisotropic relaxation rates of at least two order of magnitude lower than in GaAs.
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http://arxiv.org/abs/1206.6906
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