Metallic transport of hard core bosons

TL;DR

This paper investigates the transport properties of two-dimensional hard core bosons, revealing linear resistivity growth, Hall coefficient behavior, and implications for superconductors with short coherence lengths.

Contribution

It provides a detailed calculation of conductivities and Hall coefficients of hard core bosons using thermodynamic expansions of Kubo formulas, including higher-order corrections.

Findings

Resistivity rises linearly above the superfluid transition.

Hall coefficient diverges and changes sign at half filling.

High temperature thermal Hall coefficient reverses sign relative to electric Hall coefficient.

Abstract

Conductivities and Hall coefficients of two dimensional hard core bosons are calculated using the thermodynamic expansions of Kubo formulas. At temperatures above the superfluid transition, the resistivity rises linearly and is weakly dependent on boson filling. The zeroth order Hall coefficient diverges toward zero and unit fillings, and reverses its sign at half filling. The correction terms, which are calculated up to fourth (Krylov) orders, do not alter this behavior. The high temperature thermal Hall coefficient is reversed relative to the electric Hall coefficient. We discuss relevance of HCB transport to the metallic state of short coherence length superconductors.