Dependence of dynamic nuclear polarization on resonant spin amplification and external field history under periodic optical electron spin pumping

Greater control of nuclear spin polarization could provide breakthroughs in both classical and quantum information storage and processing. We use optical pump-probe techniques in a gallium arsenide epilayer to manipulate an electron spin polarization that persists over several pulse cycles¹. The interference of spins excited from different pulses in a swept external magnetic field results in resonant spin amplification (RSA), and we demonstrate a dynamic nuclear polarization perpendicular to the electron spin polarization that actively responds to the external field sweep direction and magnitude of RSA. We also show that the electron-nuclear spin system retains memory of the external field history, including interruptions and reversals in magnetic field sweeps, and present a model that explains key features of these results.
¹M. Macmahon, J. Iafrate, M. Dominguez, and V. Sih, arXiv:1810.00055.