# A quantitative description of Nernst effect in high-temperature superconductors

## TL;DR

This paper presents a comprehensive vortex-fluid model for flux-flow resistivity and Nernst signal in high-temperature superconductors, accurately describing experimental data and extracting key vortex dynamics parameters.

## Contribution

It introduces a refined vortex-fluid model that incorporates flux pinning and vortex-vortex collisions, providing precise descriptions of Nernst signals and flux resistivity in HTSCs.

## Key findings

- Accurate modeling of Nernst signal and flux resistivity across various samples.
- Discrepancy identified and corrected in Anderson's Nernst model.
- Method developed to extract vortex dynamics parameters from Nernst data.

## Abstract

A quantitative vortex-fluid model for flux-flow resistivity $\rho$ and Nernst signal $e_N$ in high-temperature superconductors (HTSC) is proposed. Two kinds of vortices, magnetic and thermal, are considered, and the damping viscosity $\eta$ is modeled by extending the Bardeen-Stephen model to include the contributions of flux pinning at low temperature and in weak magnetic fields, and vortex-vortex collisions in strong magnetic fields. Remarkably accurate descriptions for both Nernst signal of six samples and flux flow resistivity are achieved over a wide range of temperature $T$ and magnetic field $B$. A discrepancy of three orders of magnitude between data and Anderson's model of Nernst signal is pointed out and revised using experimental values of $\eta$ from magnetoresistance. Furthermore, a two-step procedure is developed to reliably extract, from the Nernst signal, a set of physical parameters characterizing the vortex dynamics, which yields predictions of local superfluid density $n_s$, the Kosterlitz coefficient $b$ of thermal vortices, and upper critical field and temperature. Application of the model and systematic measurement of relevant physical quantities from Nernst signal in other HTSC samples are discussed.