Nuclear spin polarization can be pumped into spin-blocked quantum dots by multiple Landau- Zener passages through singlet-triplet anticrossings. By numerical simulations of realistic systems including approximately 107 nuclear spins during 105 sweeps, we uncover a mechanism of dynamical self-quenching which results in a fast saturation of the nuclear polarization under stationary pumping. This is caused by screening of the field of the nuclear spins. In systems with moderate spin-orbit coupling, self-quenching also screens the spin-orbit interaction. The mechanism is generic and remains robust under a moderate noise. Our finding explains low polarization levels achieved experimentally and calls for developing new protocols that break the self-quenching limitations.
@article{arxiv.1206.0100,
title = {Dynamical Self-Quenching of Spin Pumping into Double Quantum Dots},
author = {Arne Brataas and Emmanuel I. Rashba},
journal= {arXiv preprint arXiv:1206.0100},
year = {2015}
}