Orientation of hole quantum Hall nematic phases in an out-of-plane electric field

Abstract

We present observations of an anisotropic resistance state at Landau level filling factor $\hat{I}½=5/2$ in a two-dimensional hole system (2DHS), which occurs for certain values of hole density $p$ and average out-of-plane electric field $E_{\perp }$. The 2DHS is induced by electric field effect in an undoped GaAs/AlGaAs quantum well, where front and back gates allow independent tuning of $p$ and $E_{\perp }$, and hence the symmetry of the confining potential. For $p\approx 2\times 10^{11}$~cm${}^{-2}$ and $E_{\perp }\approx -2\times 10^5$~V/m, the magnetoresistance along $⟨01\bar{1}⟩$ greatly exceeds that along $⟨011⟩$, suggesting the formation of a quantum Hall nematic or `stripe' phase. Reversing the sign of $E_{\perp }$ rotates the stripes by $90^{\circ }$. We suggest this behavior may arise from the mixing of the hole Landau levels and a combination of the Rashba and Dresselhaus spin-orbit coupling effects.

7 pages, 5 figures