Non-equilibrium excited-state fractionally quantized Hall effects observed via current bias spectroscopy

Abstract

Abstract Studies of fractional quantum Hall effects (FQHE) across various two-dimensional electronic systems (2DES) have helped to establish the equilibrium FQHE many-body ground states with fractionally charged excitations and composite particles in condensed matter. Then, the question arises whether an FQHE system driven to non-equilibrium can approach a different stationary state from the known equilibrium FQHE states. To investigate this question, we examine FQHE over filling factors, ν, 2 ≥ ν ≥ 1 under non-equilibrium finite bias conditions realized with a supplementary d c-current bias, I D C , in high mobility GaAs/AlGaAs devices. Here, we show that all observable canonical equilibrium FQHE resistance minima at ∣I D C ∣ = 0 undergo bimodal splitting vs. I D C , yielding branch-pairs and diamond shapes in color plots of the diagonal resistance, as canonical FQHE are replaced, with increasing I D C , by excited-state fractionally quantized Hall effects at branch intersections. A tunneling model serves to interpret the results.