We present nuclear spin relaxation measurements in GaAs epilayers using a new pump-probe technique
in all-electrical, lateral spin-valve devices. The measured T1 times agree very well with NMR data
available forT >1 K. However, the nuclear spin relaxation rate clearly deviates from the well-established
Korringa law expected in metallic samples and follows a sublinear temperature dependence T
1-1~T^0.6 for
0.1 K < T < 10 K. Further, we investigate nuclear spin inhomogeneities.