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

We address the question whether a Fractional Quantum Hall Effect (FQHE) system driven to non-equilibrium conditions 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 dc-current bias, I_DC, in high mobility GaAs/AlGaAs devices. Here, we show that all observable canonical equilibrium FQHE resistance minima at ∣I_DC∣ = 0 undergo bimodal splitting vs. I_DC, yielding branch-pairs and diamond shapes in color plots of the diagonal resistance, as canonical FQHE are replaced, with increasing I_DC, by some excited-state fractionally quantized Hall effects at branch intersections. The results suggest a magneto-transport realization of non-equilibrium excited state fractionally quantized Hall effects.