Transport in two-dimensional disordered semimetals

TL;DR

This paper models electrical transport in two-dimensional semimetals with disorder, revealing an abrupt resistivity increase at low temperatures due to electron-hole interactions, relevant for experimental systems.

Contribution

It introduces a theoretical framework combining effective medium approximation and resistor network mapping to analyze transport in disordered 2D semimetals with electron-hole puddles.

Findings

Resistivity sharply increases at low temperatures with smooth disorder.

No divergence in resistivity at zero temperature.

Behavior explained by electron-hole overlap and weak recombination.

Abstract

We theoretically study transport in two-dimensional semimetals. Typically, electron and hole puddles emerge in the transport layer of these systems due to smooth fluctuations in the potential. We calculate the electric response of the electron-hole liquid subject to zero and finite perpendicular magnetic fields using an effective medium approximation and a complimentary mapping on resistor networks. In the presence of smooth disorder and in the limit of weak electron-hole recombination rate, we find for small but finite overlap of the electron and hole bands an abrupt upturn in resistivity when lowering the temperature but no divergence at zero temperature. We discuss how this behavior is relevant for several experimental realizations and introduce a simple physical explanation for this effect.