Enhancement of Coulomb drag away from half filled Landau levels

TL;DR

This study investigates Coulomb drag in two-dimensional electron gases at high magnetic fields, revealing a quadratic enhancement of drag magnitude as the filling factor deviates from 1/2, independent of layer spacing or sign of deviation.

Contribution

It demonstrates that Coulomb drag enhancement away from half filling is quadratic and not caused by non-perturbative interlayer correlations, providing new insights into electron interactions.

Findings

Drag magnitude increases quadratically with deviation from nu=1/2

Enhancement is insensitive to layer spacing and sign of deviation

Results suggest non-perturbative correlations are not responsible

Abstract

Coulomb drag between two parallel two dimensional electron gases has been measured at high magnetic fields in samples with two different layer spacings. As the layer filling factor deviates from nu=1/2, we find that the magnitude of the drag is enhanced quadratically with Delta nu = nu - 1/2, and the curvature of the enhancement is insensitive to both the sign of Delta nu and the spacing between the layers. Our results suggest that the enhancement is not due to non-perturbative interlayer correlations.