Negative magnetoresistance temperature dependence induced by current-pumped nuclear spin polarization at the ν=2/3 quantum Hall state

We investigate the huge longitudinal resistance (HLR) at which the magnetoresistance of the nu = 2/3 fractional quantum Hall state (QHS) is increased with dynamic nuclear spin polarization. We measure the magnetoresistance temperature dependence in the resistively saturated HLR by increasing the temperature of the sample rapidly in order to prevent relaxation of the nuclear spin polarization. The obtained results indicate that the magnetoresistance decreases as the temperature increases. The Hall resistance in the HLR is also measured and found to exhibit a plateau close to a quantized value. We discuss the negative magnetoresistance temperature dependence with a stripe-shaped domain state deformed by the nuclear spin polarization.