Anomalous dissipation in the mixed state of underdoped cuprates close to the superconductor-insulator boundary

TL;DR

This study compares Nernst effect and resistivity in underdoped cuprates, revealing complex dissipation mechanisms near the superconductor-insulator boundary, with evidence of quantum fluctuations and vortex behavior.

Contribution

It provides new insights into the dissipation mechanisms in the mixed state of underdoped cuprates near the superconductor-insulator transition.

Findings

Nernst effect peaks where resistivity is non-metallic

Quantum fluctuations are significant near the boundary

Vortex viscosity vanishes close to the transition

Abstract

We present a comparative study of Nernst effect and resistivity in underdoped samples of Bi$_2$Sr$_2$CuO$_{6+\delta}$ and La$_{2-x}$Sr$_{x}$CuO$_4$. The Nernst effect presents a peak in a region of the H-T diagram where resistivity shows a non-metallic temperature dependence. Our results illustrate that the mechanism of dissipation in the mixed state of underdoped cuprates is poorly understood. Large quantum superconducting fluctuations and vanishing vortex viscosity are among suggested explanations for an enhanced Nernst signal close to the superconductor-insulator boundary.