We report low-field magnetotransport data in two-dimensional hole systems in GaAs/AlGaAs heterostructures and quantum wells, in a large density range, 2.5×1010≤p≤4.0×1011 cm−2, with primary focus on samples grown on (311)A GaAs substrates. At high densities, p≳1×1011 cm−2, we observe a remarkably strong positive magnetoresistance. It appears in samples with an anisotropic in-plane mobility and predominantly along the low-mobility direction, and is strongly dependent on the perpendicular electric field and the resulting spin-orbit interaction induced spin-subband population difference. A careful examination of the data reveals that the magnetoresistance must result from a combination of factors including the presence of two spin-subbands, a corrugated quantum well interface which leads to the mobility anisotropy, and possibly weak anti-localization. None of these factors can alone account for the observed positive magnetoresistance. We also present the evolution of the data with density: the magnitude of the positive magnetoresistance decreases with decreasing density until, at the lowest density studied (p=2.5×1010 cm−2), it vanishes and is replaced by a weak negative magnetoresistance.
@article{arxiv.cond-mat/0201491,
title = {Low-field magnetoresistance in GaAs 2D holes},
author = {S. J. Papadakis and E. P. De Poortere and H. C. Manoharan and J. B. Yau and M. Shayegan and S. A. Lyon},
journal= {arXiv preprint arXiv:cond-mat/0201491},
year = {2009}
}