Nernst Effect and Superconducting Fluctuations in Zn-doped YBa$_{2}$Cu$_{3}$O$_{7-\delta}$

TL;DR

This study investigates how Zn doping affects the Nernst effect, pseudogap temperature, and superconductivity in YBa₂Cu₃O₇−δ thin films, revealing that Zn impurities suppress superconductivity and vortex-like excitations.

Contribution

It provides new insights into the impact of Zn impurities on vortex dynamics and pseudogap behavior in high-temperature superconductors.

Findings

Pseudogap temperature $T^*$ remains nearly unchanged with Zn doping.

Onset temperature $T^{ u}$ of Nernst signal decreases sharply with Zn doping.

Maximum vortex Nernst signal diminishes as Zn content increases.

Abstract

We report the measurements of in-plane resistivity, Hall effect, and Nernst effect in Zn doped YBa$_{2}$Cu$_{3}$O$_{7-\delta}$ epitaxial thin films grown by pulsed laser deposition technique. The pseudogap temperature, $T^*$, determined from the temperature dependence of resistivity, does not change significantly with Zn doping. Meanwhile the onset temperature ($T^{\nu}$) of anomalous Nernst signal above $T_{c0}$, which is interpreted as evidence for vortex-like excitations, decreases sharply as the superconducting transition temperature $T_{c0}$ does. A significant decrease in the maximum of vortex Nernst signal in mixed state is also observed, which is consistent with the scenario that Zn impurities cause a decrease in the superfluid density and therefore suppress the superconductivity. The phase diagram of $T^*$, $T^{\nu}$, and $T_{c0}$ versus Zn content is presented and discussed.