Time dependent measurements of dynamic nuclear polarization growth under periodic optical electron spin pumping in gallium arsenide

Through dynamic nuclear polarization, optically pumped electron spins polarize the nuclear spin system in gallium arsenide. The effective magnetic field from the polarized nuclear spins will affect the Larmor precession frequency of the electron spin system, which will synchronize to discrete integer or half integer values; this is known as nuclear-induced frequency focusing. The rate of dynamic nuclear polarization is dependent on the coupling between the electron and nuclear spin systems. Observations from optical pump probe Kerr rotation experiments show nuclear polarization growth behavior dependence on pump wavelength and external field. These lab time dependent observations are corroborated by calculations with a model using the optical Stark effect.