Quantum Hall plateau-plateau transition revisited

We observe a temperature-independent point B_c in the longitudinal resistance R_xx of a GaAs-based two-dimensional electron gas in the quantum Hall plateau-plateau transition. This allows us to revisit the spin-degenerate plateau-plateau transition and use the R_xx peak movement with respect to B_c at various temperatures T so as to calculate the critical exponent κ. We suggest that one measures the maximum of the derivative of Hall resistivity dρ_xy/dB ∼ T^−κ as well as the movement of R_xx at different temperatures, allowing one to measure κs using two independent methods. When the peak movement is so large that the resistance peak is no longer in the vicinity of B_c, a largely deviated κ =0.54±0.04 from the value (0.21±0.02 ) in some spin-degenerate system can be measured.