Abstract
We present observations of an anisotropic resistance state at Landau level filling factor ν=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_⊥. 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_⊥, and hence the symmetry of the confining potential. For p≈2×10¹¹~cm⁻² and E_⊥ ≈ -2 ×10⁵~V/m, the magnetoresistance along 011 greatly exceeds that along 011, suggesting the formation of a quantum Hall nematic or `stripe' phase. Reversing the sign of E_⊥ rotates the stripes by 90^∘. 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.