History-Dependent Dynamic Nuclear Polarization in Gallium Arsenide in the Resonant Spin Amplification Regime*

Dynamic nuclear polarization (DNP) arises through the interaction of atomic nuclei in a material with spin-polarized electrons. An optically-driven electron system transfers spin polarization to the nuclei. In turn, nuclear spins produce a magnetic field that affects electron spin precession frequency. We use a pulsed laser to excite and measure electron spin polarization in a gallium arsenide epilayer, in the regime of resonant spin amplification. By measuring Kerr rotation as a function of applied magnetic field, we can detect the influence of the nuclear spins. We report an unexpected dependence of DNP on both magnetic field history and transverse electron spin polarization [1]. Variations of the applied field sequence and duration reveal a minutes-long precise memory of the particular field history of the system.

[1] M. Macmahon, J.R. Iafrate, M.J. Dominguez, and V. Sih, arXiv:1810.00055.