Tunneling Between Two-Dimensional Electron Gases in a Strong Magnetic Field

TL;DR

This paper investigates tunneling between two-dimensional electron gases in high magnetic fields, revealing a gap and tunneling peak that suggest a different magnetic field dependence than current theories predict.

Contribution

It provides new measurements of tunneling peak positions and gap parameters, challenging existing theories by showing a linear B dependence instead of the expected square root dependence.

Findings

Observed a gap in current-voltage characteristics at $ u<1$

Tunneling peak position scales linearly with magnetic field

Gap parameters are independent of carrier densities

Abstract

We have measured the tunneling between two two-dimensional electron gases at high magnetic fields $B$, when the carrier densities of the two electron layers are matched. For filling factors $\nu<1$, there is a gap in the current-voltage characteristics centered about $V=0$, followed by a tunneling peak at $\sim 6$~mV. Both features have been observed before and have been attributed to electron-electron interactions within a layer. We have measured high field tunneling peak positions and fitted gap parameters that are proportional to $B$, and independent of the carrier densities of the two layers. This suggests a different origin for the gap to that proposed by current theories, which predict a $\sqrt{B}$ dependence.