Probing Insulator-quantum Hall Transitions by Current Heating

Abstract

We report a magneto-transport study on the two-dimensional electron system (2DES) in an AlGaAs/GaAs heterostructure. The direct insulator to quantum Hall conductor transition is observed at low temperatures by increasing the magnetic field B perpendicular to the 2DES. We can also observe the transition by varying the current I and find a relation T(e) similar to I(a) between electron effective temperature T(e) and current. Here, a denotes the exponent for the power law. The exponent a, however, can have different values on the two sides of the transition point, which indicates different inelastic scattering mechanisms in the low-field insulator and in the quantum Hall conductor.