Charge density wave and finite-temperature transport in minimally twisted bilayer graphene

TL;DR

This paper investigates how electron-electron interactions in minimally twisted bilayer graphene lead to charge density wave states and influence finite-temperature electrical transport, revealing new interaction-driven phenomena.

Contribution

It demonstrates the formation of a spin-gapped charge density wave state and its impact on resistivity, highlighting the role of domain-wall networks in transport properties.

Findings

Charge density wave state forms at low temperatures.

Resistivity exhibits a minimum at intermediate temperatures.

Power-law temperature dependence of resistivity due to umklapp scattering.

Abstract

We study phenomena driven by electron-electron interactions in the minimally twisted bilayer graphene (mTBLG) with a perpendicular electric field. The low-energy degrees of freedom in mTBLG are governed by a network of one-dimensional domain-wall states, described by two channels of one-dimensional linearly dispersing spin-1/2 fermions. We show that the interaction can realize a spin-gapped inter-channel charge density wave (CDW) state at low temperatures, forming a "Coulomb drag" between the channels and leaving only one charge conducting mode. For sufficiently high temperatures, power-law-in-temperature resistivity emerges from the charge umklapp scatterings within a domain wall. Remarkably, the presence of the CDW states can strengthen the charge umklapp scattering and induce a resistivity minimum at an intermediate temperature corresponding to the CDW correlation energy. We further discuss the conditions that resistivity of the network is dominated by the domain walls. In particular, the power-law-in-temperature resistivity results can apply to other systems that manifest topological domain-wall structures.