Systematic investigations of transient response of nuclear spins in the presence of polarized electrons

Abstract

We electrically probed the transient response of nuclear spins in an n-GaAs channel by performing Hanle signal and spin-valve signal measurements on an all-electrical spin-injection device having a half-metallic spin source of Co 2 MnSi. Furthermore, we simulated the Hanle and spin-valve signals by using the time evolution of nuclear-spin polarization under the presence of polarized electron spins by taking both T 1e and T 1 into consideration, where T −1 1e is the polarization rate of nuclear spins through the transfer of angular momentum from polarized electron spins and T −1 1 is the depolarization rate of nuclear spins through the interaction with the lattice. The simulation results reproduced our experimental results on all the nuclear-spin-related phenomena appearing in the Hanle and spin-valve signals at different measurement conditions, providing quantitative explanation for the transient response of nuclear spins in GaAs to a change in magnetic fields and an estimate of the time scales of T 1e and T 1 . These experimental and simulated results will deepen the understanding of nuclear-spin dynamics in semiconductors.

Dipolelike dynamical nuclear spin polarization around a quantum point contact

“…We now consider a situation with non-equilibrium spin polarizations in the leads [46]. The latter corresponds to having spin-dependent chemical potentials…”