Anisotropic magnetotransport around the ν=1 bilayer quantum Hall state

An anisotropic magnetotransport that depends on a direction of an in-plane magnetic field was investigated in a bilayer quantum Hall system. We have found that the longitudinal resistance around the bilayer ν=1 quantum Hall state strongly varies when we changed the relative angle between the current and the in-plane field. Indeed, the anisotropy becomes remarkable at the phase transition point between the commensurate and incommensurate states. This result suggests that a unidirectional state appears around the transition.