• Hamer, Matthew J.

Abstract

Electron-electron interactions play a critical role in many condensed matter phenomena, and it is tempting to find a way to control them by changing the interactions' strength. One possible approach is to place a studied electronic system in proximity of a metal, which induces additional screening and hence suppresses electron interactions. Here, using devices with atomically-thin gate dielectrics and atomically-flat metallic gates, we measure the electron-electron scattering length in graphene at different concentrations and temperatures. The proximity screening is found to enhance the e-e length and change qualitatively its concentration dependence. Counterintuitively, the screening becomes important only at gate dielectric thicknesses of a few nm, much smaller than the average separation between electrons. The critical thickness is given by ~0.03 [average separation ] * [gate dielectric's permittivity ] , and the theoretical expression agrees well with our experiment. The work shows that, using van der Waals heterostructures with ultra-thin dielectrics, it is possible to modify many-body phenomena in adjacent electronic systems.

Topics

• impedance spectroscopy
• experiment
• strength