  We study dynamic polarization and resistive detection of nuclear spins in a
semiconductor quantum dot (QD) under the Kondo effect regime. We find that the
differential conductance spectra of the QD exhibit hysteresis under the Kondo
effect regime in magnetic fields. Relevance of nuclear spins to the hysteresis
is confirmed by the detection of nuclear magnetic resonance signals by
monitoring the differential conductance. We attribute the origin of the
hysteresis to the dynamic nuclear spin polarization (DNP) induced in the QD.
Using the DNP, we demonstrate nuclear spin relaxation rate measurements in the
QD under the Kondo effect regime.
