Phase Transition to Insulating State from Quantum Hall State by Current-Induced Nuclear Spin Polarization

We investigate the resistance enhancement state (RES) where the magnetoresistance of the $\nu = 2/3$ fractional quantum Hall state (FQHS) is increased with dynamic nuclear spin polarization (DNP) induced by a large electric current. After inducing DNP, we measure the temperature dependence of the magnetoresistance by a small current over a short period of time. We find that the FQHS makes a phase transition to an insulating state. By measuring the Hall resistance in the insulating state, we find that the RES exhibits a quantized Hall resistance. We discuss the RES in association with the Anderson localization.