Phonon mediated drag in double layer two dimensional electron systems

TL;DR

This study investigates phonon-mediated drag in double layer 2D electron systems, analyzing how it varies with parameters and comparing results to theoretical models predicting coupled electron-phonon modes.

Contribution

It provides detailed experimental data on phonon-mediated drag and evaluates the validity of theoretical models predicting coupled electron-phonon collective modes.

Findings

Layer spacing and density dependence do not support the coupled mode for spacings below 2600 Å.

Drag magnitude suggests strong electron-phonon coupling in some regimes.

Discrepancies observed at larger layer spacings challenge existing theories.

Abstract

Experiments studying phonon mediated drag in the double layer two dimensional electron gas system are reported. Detailed measurements of the dependence of drag on temperature, layer spacing, density ratio, and matched density are discussed. Comparisons are made to theoretical results [M. C. Bonsager et al., Phys. Rev. B 57, 7085 (1998)] which propose the existence of a new coupled electron-phonon collective mode. The layer spacing and density dependence at matched densities for samples with layer spacings below 2600 A do not support the existence of this mode, showing behavior expected for independent electron and phonon systems. The magnitude of the drag, however, suggests the alternate limit; one in which electrons and phonons are strongly coupled. The results for still larger layer spacing show significant discrepancies with the behavior expected for either limit.