The time evolution of a local spin excitation in a (001)-confined two-dimensional electron gas subjected to Rashba and Dresselhaus spin-orbit interactions of similar strength is investigated theoretically and compared with experimental data. Specifically, the consequences of the finite spatial extension of the initial spin polarization is studied for non-balanced Rashba and Dresselhaus terms and for finite cubic Dresselhaus spin-orbit interaction. We show that the initial out-of-plane spin polarization evolves into a helical spin pattern with a wave number that gradually approaches the value q0 of the persistent spin helix mode. In addition to an exponential decay of the spin polarization that is proportional to both the spin-orbit imbalance and the cubic Dresselhaus term, the finite width w of the spin excitation reduces the spin polarization by a factor that approaches exp(−q02w2/2) at longer times.
@article{arxiv.1312.5529,
title = {Dynamics of a localized spin excitation close to the spin-helix regime},
author = {G. Salis and M. P. Walser and P. Altmann and C. Reichl and W. Wegscheider},
journal= {arXiv preprint arXiv:1312.5529},
year = {2015}
}