Probing the Gauge Structure of high-temperature superconductors

TL;DR

This paper explores how non-Abelian gauge theories in doped antiferromagnets can explain the pseudogap phase in high-temperature superconductors, supported by theoretical arguments and experimental thermal conductivity measurements.

Contribution

It introduces a gauge-theoretic framework for the pseudogap phase, linking non-perturbative effects to experimental observables in high-T_c superconductors.

Findings

Non-perturbative effects influence pseudogap formation.

Thermal conductivity scales with magnetic field in predicted ways.

Gauge interactions can be probed experimentally through thermal measurements.

Abstract

We suggest that a spin-charge separating ansatz, leading to non-Abelian $SU(2) \otimes U_S(1)$ gauge symmetries in doped antiferromagnets, proposed earlier as a way of describing Kosterlitz-Thouless superconducting gaps at the nodes of the gap of d-wave (high-T_c) superconductors, may also lead to a pseudogap phase, characterised by the formation of (non-superconducting) pairing and the absence of phase coherence. The crucial assumption is again the presence of electrically charged Dirac fermionic excitations (holons) about the points of the (putative) fermi surface in the pertinent phase of the superconductor. We present arguments in support of the r\^ole of non-perturbative effects (instantons) on the onset of the pseudogap phase. As a means of probing such gauge interactions experimentally, we perform a study of the scaling of the thermal conductivity with an externally-applied magnetic field, in certain effective models involving gauge and/or four-fermion (contact) interactions.