Collision-dominated conductance in clean 2D metals

TL;DR

This paper investigates how electron-electron interactions affect conductance in clean 2D metals, revealing that at low temperatures, conductance approaches the ballistic limit with unique temperature-dependent corrections.

Contribution

It provides a theoretical analysis of temperature-dependent conductance corrections in 2D metals using Boltzmann kinetic theory, highlighting the role of scattering modes and symmetry constraints.

Findings

Conductance tends to the ballistic limit at low temperatures.

Correction scales as (T/E_F) * sqrt(log(E_F/T)).

Results apply to 2D systems with convex Fermi surfaces.

Abstract

We study the temperature-dependent corrections to the conductance due to electron-electron (e-e) interactions in clean two-dimensional conductors, such as lightly doped graphene or other Dirac matter. We use semiclassical Boltzmann kinetic theory to solve the problem of collision-dominated transport between reflection-free contacts. Time-reversal symmetry and the kinematic constraints of scattering in two dimensions (2D) ensure that inversion-odd and inversion-even distortions of the quasiparticle distribution relax with parametrically different rates at low temperature. This entails the surprising result that at lowest temperatures the conductance of very long samples tends to the noninteracting, ballistic conductance, despite the relaxation of the quasiparticle distribution to a drifting equilibrium. The relative correction to the conductance depends on the ratio of relaxation rates of even and odd modes and scales as delta G/G_{ballistic}~(T/E_F)[Log(E_F/T)]^{1/2}, in stark contrast to the behavior in other dimensionalities. This holds generally in 2D systems with simply connected and convex but otherwise arbitrary Fermi surfaces, as long as e-e scattering processes are dominant and umklapp scattering is negligible. These results are especially relevant to the bulk of wide and long suspended high-mobility graphene sheets.