Magnetic field dependence of Pauli spin blockade: A window into the sources of spin relaxation in silicon quantum dots

We investigate spin relaxation in a silicon double quantum dot via leakage current through Pauli blockade as a function of interdot detuning and magnetic field. A dip in leakage current as a function of magnetic field on an $\ensuremath{\sim}40$ mT field scale is attributed to spin-orbit mediated spin relaxation. On a larger ($\ensuremath{\sim}400$ mT) field scale, a peak in leakage current is seen in some, but not all, Pauli-blocked transitions, and is attributed to spin-flip cotunneling. Both dip and peak structure show good agreement between theory and experiment.

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