Confinement symmetry, mobility anisotropy, and metallic behavior in (311)A GaAs two-dimensional holes

We study two-dimensional hole systems confined to (311)A GaAs quantum wells. Such samples exhibit an in-plane mobility anisotropy. At constant hole density, we vary the symmetry of the quantum well potential, and thus the spin-orbit interaction-induced spin splitting, and measure the temperature dependence of the resistivity along two different in-plane current directions, in a regime where the samples exhibit metallic behavior. Both the symmetry and the current direction have a significant effect on the metallic behavior. The results point to the importance of both intersubband and interface-roughness scattering in any quantitative explanation of the low-temperature transport characteristics of this system.