  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 a \sim 40 mT
field scale is attributed to spin-orbit mediated spin relaxation. On a larger
(\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.
