Tunneling measurements of the coulomb pseudogap in a two-dimensional electron system in a quantizing magnetic field

TL;DR

This study investigates the Coulomb pseudogap in a two-dimensional electron system under high magnetic fields, revealing its linear energy dependence and different behaviors at fractional filling factors, advancing understanding of quantum Hall effects.

Contribution

It provides new insights into the filling factor dependence of the Coulomb pseudogap and confirms the existence of a separate relaxation time at ν ≈ 1.

Findings

Pseudogap is linear in energy with a filling factor-dependent slope.

Different tunneling behaviors observed at fractional filling factors ν=1/3 and 2/3.

Confirmation of a separate relaxation time for tunneling at ν ≈ 1.

Abstract

We study the Coulomb pseudogap for tunneling into the two-dimensional electron system of high-mobility (Al,Ga)As/GaAs heterojunctions subjected to a quantizing magnetic field at filling factor $\nu \leq 1$. Tunnel current-voltage characteristics show that for the double maximum observed in the tunnel resistance at $\nu \approx 1$ the pseudogap is linear in energy with a slope that depends on filling factor, magnetic field, and temperature. We give a qualitative account of the filling factor dependence of the pseudogap slope and we confirm the recently reported appearance of another relaxation time for tunneling at $\nu \approx 1$. For the tunnel resistance peaks at $\nu=1/3$ and 2/3 a completely different behaviour of the current-voltage curves is found and interpreted as manifestation of the fractional gap.