We present quantitative measurements and calculations of the spin-orbit induced zero-magnetic-field spin-splitting in two-dimensional (2D) hole systems in modulation-doped GaAs (311)A quantum wells. The results show that the splitting is large and tunable. In particular, via a combination of back- and front-gate biases, we can tune the splitting while keeping the 2D hole density constant. The data also reveal a surprising result regarding the magnetoresistance (Shubnikov-de Haas) oscillations in a 2D system with spin-split energy bands: the frequencies of the oscillations are {\it not} simply related to the population of the spin-subbands. Next we concentrate on the metallic-like behavior observed in these 2D holes and its relation to spin-splitting. The data indicate that the metallic behavior is more pronounced when two spin-subbands with unequal populations are occupied. Our measurements of the magnetoresistance of these 2D hole systems with an in-plane magnetic field corroborate this conclusion: while the system is metallic at zero magnetic field, it turns insulating when one of the spin-subbands is depopulated at high magnetic field.
@article{arxiv.cond-mat/0006497,
title = {Spin-splitting in GaAs 2D holes},
author = {S. J. Papadakis and E. P. De Poortere and M. Shayegan and R. Winkler},
journal= {arXiv preprint arXiv:cond-mat/0006497},
year = {2009}
}
Comments
To be published in Physica E, as part of the proceedings of the 11th International Winterschool on New Developments in Solid State Physics held in Mauterndorf, Austria, February, 2000