Interaction-protected topological insulators with time reversal symmetry

Anderson's localization on the edge of a two-dimensional time reversal topological insulator (TI) is studied. For the noninteracting case, the topological protection acts according to the Z(2) classification, leading to conducting and insulating phases for odd and even fillings, respectively. In the presence of repulsive interaction, the phase diagram is notably changed. We show that for sufficiently strong values of the interaction, the zero-temperature fixed point of the TI is conducting, including the case of even fillings. We compute the boundaries of the conducting phase for various fillings and types of disorder.