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

TL;DR

This study investigates tunneling between two-dimensional electron gases in weak magnetic fields, revealing how magnetic field influences tunneling conductance and Coulomb gap characteristics.

Contribution

It provides experimental insights into tunneling behavior in 2DEGs under weak magnetic fields, extending understanding from high to low field regimes.

Findings

Lorentzian lineshape at zero field determined by barrier roughness

Suppression of tunneling conductance at non-zero magnetic fields

Linear B dependence of Coulomb gap at high filling factors

Abstract

We have measured the tunneling between two two-dimensional electron gases (2DEGs) in weak magnetic fields, when the carrier densities of the two electron layers are matched. At zero magnetic field, B=0, the lineshape of the equilibrium tunneling resonance is best fit by a Lorentzian, with a linewidth which is determined by the roughness of the tunnel barrier. For $B\not=0$ with filling factors $\nu\gg 1$, there is a suppression of the resonant tunneling conductance about zero bias, $V_{\text{sd}}=0$. This low field signature of the high field Coulomb gap shows the same linear $B$ dependence as previously measured for $\nu<1$.