Universal transport near a quantum critical Mott transition in two dimensions

TL;DR

This paper investigates the universal transport properties near a quantum critical Mott transition in two dimensions, highlighting the role of emergent gauge fields and fractionalization in the transition between a Fermi liquid and a quantum spin liquid.

Contribution

It provides a controlled calculation of the universal resistivity jump and predicts a universal thermal conductivity jump, linking gauge fluctuations to observable transport signatures.

Findings

Universal resistivity jump at the Mott transition

Violation of Wiedemann-Franz law in the quantum critical region

Universal thermal conductivity jump predicted

Abstract

We discuss the universal transport signatures near a zero-temperature continuous Mott transition between a Fermi liquid (FL) and a quantum spin liquid in two spatial dimensions. The correlation-driven transition occurs at fixed filling and involves fractionalization of the electron: upon entering the spin liquid, a Fermi surface of neutral spinons coupled to an internal gauge field emerges. We present a controlled calculation of the value of the zero temperature universal resistivity jump predicted to occur at the transition. More generally, the behavior of the universal scaling function that collapses the temperature and pressure dependent resistivity is derived, and is shown to bear a strong imprint of the emergent gauge fluctuations. We further predict a universal jump of the thermal conductivity across the Mott transition, which derives from the breaking of conformal invariance by the damped gauge field, and leads to a violation of the Wiedemann-Franz law in the quantum critical region. A connection to organic salts is made, where such a transition might occur. Finally, we present some transport results for the pure rotor O(N) CFT.