Gauge approach to the specific heat in the normal state of cuprates

TL;DR

This paper uses a gauge theoretical approach to explain the unusual temperature dependence of specific heat and entropy in the normal state of high-temperature cuprate superconductors, highlighting the role of gauge fluctuations and fermionic excitations.

Contribution

It introduces a gauge approach to the t-J model that reproduces key experimental features of specific heat and entropy in cuprates, emphasizing the role of gauge field fluctuations.

Findings

Reproduces nontrivial temperature dependence of specific heat coefficient.

Explains negative entropy intercept at T=0 in pseudogap phase.

Identifies gauge field fluctuations as key to thermodynamic behavior.

Abstract

Many experimental features of the electronic specific heat and entropy of high Tc cuprates in the normal state, including the nontrivial temperature dependence of the specific heat coefficient and negative intercept of the extrapolated entropy to T=0 for underdoped cuprates, are reproduced using the spin-charge gauge approach to the t-J model. The entropy turns out to be basically due to fermionic excitations, but with a temperature dependence of the specific heat coefficient controlled by fluctuations of a gauge field coupling them to gapful bosonic excitations. In particular the negative intercept of the extrapolated entropy at T=0 in the pseudogap ``phase'' is attributed to the scalar component of the gauge field, which implements the local no-double occupancy constraint.