Double layer two-dimensional electron systems: Probing the transition from weak to strong coupling with Coulomb drag

TL;DR

This paper investigates the transition from weak to strong coupling in bilayer two-dimensional electron systems using Coulomb drag measurements, revealing large dissipation and fluctuations near the phase boundary.

Contribution

It introduces Coulomb drag as a probe to study the transition between different coupling regimes in bilayer 2D electron systems, highlighting fluctuation phenomena.

Findings

Large dissipation observed at the transition point.

Fluctuations persist beyond the phase coherence regime.

Anomalies in drag indicate complex phase boundary dynamics.

Abstract

Frictional drag measurements revealing anomalously large dissipation at the transition between the weakly- and strongly-coupled regimes of a bilayer two-dimensional electron system at total Landau level filling factor $\nu_T =1$ are reported. This result suggests the existence of fluctuations, either static or dynamic, near the phase boundary separating the quantized Hall state at small layer separations from the compressible state at larger separations. Interestingly, the anomalies in drag seem to persist to larger layer separations than does interlayer phase coherence as detected in tunneling.