Measuring electron-electron scattering rates through mutual friction

Electron-electron (e-e) interactions have been probed using a new measurement technique which provides direct determination of e-e scattering rates. The technique measures the voltage induced in one two-dimensional electron gas (2DEG) when a current is driven through a second, parallel, 2DEG. Measurements with closely spaced layers confirm the importance of Coulomb scattering in the interlayer e-e interaction. For large layer spacings, however, Coulomb scattering diminishes rapidly and a second mechanism dominates. Measurements indicate that the strong interlayer interactions in this regime are due to the exchange of virtual phonons between the electron systems.