Nernst Effect and Anomalous Transport in Cuprates: A Preformed-Pair Alternative to the Vortex Scenario

TL;DR

This paper proposes that preformed pairs, rather than vortices, explain anomalous transport phenomena in underdoped high-temperature superconductors, providing a unified theoretical framework consistent with various experimental observations.

Contribution

It introduces an exact calculation of transport coefficients based on preformed pairs, offering an alternative to vortex-based explanations in high-Tc superconductors.

Findings

Semi-quantitative agreement with Nernst effect data

Consistent explanation of ac conductivity and diamagnetic measurements

Results reduce to standard fluctuation theories near optimal doping

Abstract

We address those puzzling experiments in underdoped high $T_c$ superconductors which have been associated with normal state "vortices" and show these data can be understood as deriving from preformed pairs with onset temperature $T^* > T_c$. For uncorrelated bosons in small magnetic fields, and arbitrary $T^*/T_c$, we present the exact contribution to \textit{all} transport coefficients. In the overdoped regime our results reduce to those of standard fluctuation theories ($T^*\approx T_c$). Semi-quantitative agreement with Nernst, ac conductivity and diamagnetic measurements is quite reasonable.