A construction of exotic metallic states

TL;DR

This paper constructs and analyzes two-dimensional metallic states with charge fractionalization, revealing exotic behaviors such as non-monotonic resistivity and violations of the Wiedemann-Franz law, through simple gauge-coupled fermionic models.

Contribution

It introduces new models of metallic states with charge fractionalization and explores their exotic low and intermediate temperature properties.

Findings

Resistivity can exceed the Mott-Ioffe-Regel limit at low T

Resistivity shows nonmonotonic temperature dependence

Large Lorenz number violates Wiedemann-Franz law

Abstract

We discuss examples of two dimensional metallic states with charge fractionalization, and we will demonstrate that the mechanism of charge fractionalization leads to exotic metallic behaviors at low and intermediate temperature. The simplest example of such state is constructed by fermionic partons at finite density coupled to a $Z_N$ gauge field, whose properties can be studied through rudimentary methods. This simple state has the following exotic features: (1) at low temperature this state is a "bad metal" whose resistivity can exceed the Mott-Ioffe-Regel limit; (2) while increasing temperature $T$ the resistivity $\rho(T)$ is a nonmonotonic function, and it crosses over from a bad metal at low $T$ to a good metal at relatively high $T$; (3) the optical conductivity $\sigma(\omega)$ has a small Drude weight at low $T$, and a larger Drude weight at intermediate $T$; (4) at low temperature the metallic state has a large Lorenz number, which strongly violates the Wiedemann-Franz law. A more complex example with fermionic partons at finite density coupled to a SU(N) gauge field will also be constructed.