We report low-temperature resistance measurements in a modulation-doped, (311)A GaAs two-dimensional hole system as a function of applied in-plane strain. The data reveal a strong but anisotropic piezoresistance whose magnitude depends on the density as well as the direction along which the resistance is measured. At a density of 1.6×1011 cm−2 and for a strain of about 2×10−4 applied along [011ˉ], e.g., the resistance measured along this direction changes by nearly a factor of two while the resistance change in the [2ˉ33] direction is less than 10% and has the opposite sign. Our accurate energy band calculations indicate a pronounced and anisotropic deformation of the heavy-hole dispersion with strain, qualitatively consistent with the experimental data. The extremely anisotropic magnitude of the piezoresistance, however, lacks a quantitative explanation.
@article{arxiv.0706.0736,
title = {Anisotropic low-temperature piezoresistance in (311)A GaAs two-dimensional holes},
author = {B. Habib and J. Shabani and E. P. De Poortere and M. Shayegan and R. Winkler},
journal= {arXiv preprint arXiv:0706.0736},
year = {2009}
}