Observation of an Anisotropic Wigner Crystal

We report a new correlated phase of two-dimensional charged carriers in high magnetic fields, manifested by an anisotropic insulating behavior at low temperatures. It appears in a large range of low Landau level fillings 1/3ν 2/3 in hole systems confined to wide GaAs quantum wells when the sample is tilted in magnetic field to an intermediate angle. The parallel field component (B) leads to a crossing of the lowest two Landau levels, and an elongated hole wave function in the direction of B. Under these conditions, the in-plane resistance exhibits an insulating behavior, with the resistance along B about 10 times smaller than the resistance perpendicular to B. We interpret this anisotropic insulating phase as a two-component, striped Wigner crystal.