|
CPM Seminar
René Côté Departement de Physique, Université de Sherbrooke Recent transport experiments on the two-dimensional electron gas (2DEG) in very high mobility GaAs heterojunctions have revealed unusual properties of the resistivity tensor. These new properties are observed only in Landau levels N>1 and when the upper level is close to half filling. Near half filling, the most dramatic of these new behaviors is a very large anisotropy in the diagonal components rxx and ryy of the resistivity tensor. Our current understanding of these transport properties is that they are manifestations of some new ground states of the 2DEG. Close to half filling, we believe that the system is best described as an highly anisotropic stripe phase (also called the quantum Hall smectic phase). Moving away from half filling, the stripe phase is possibly replaced by a Wigner crystal of electrons or holes or alternatively by a more exotic bubble crystal. In this talk, we will introduce these new ordered states of the 2DEG in higher Landau level, present the experimental evidences that support them and discuss some recent models that try to explain their unusual transport properties.
Wednesday, January 24th 2001, 15:30 |