Normal State Nernst Effect in Electron-doped Pr2-xCexCuO4: Superconducting Fluctuations and Two-band Transport

TL;DR

This study investigates the normal state Nernst effect in electron-doped Pr2-xCexCuO4 across various doping levels, revealing insights into superconducting fluctuations and two-band transport phenomena.

Contribution

It provides the first systematic analysis of the Nernst effect in electron-doped cuprates, highlighting the role of incoherent fluctuations and two-band transport in the normal state.

Findings

Vortex Nernst signal observed above Tc in underdoped films

Large normal state Nernst signal at high temperatures across doping levels

Anomalous Nernst effect in highly overdoped films not explained by simple Fermi surface models

Abstract

We report a systematic study of normal state Nernst effect in the electron-doped cuprates Pr$_{2-x}$Ce$_x$CuO$_{4-\delta}$ over a wide range of doping (0.05$\leq x \leq$0.21) and temperature. At low temperatures, we observed a notable vortex Nernst signal above T$_c$ in the underdoped films, but no such normal state vortex Nernst signal is found in the overdoped region. The superconducting fluctuations in the underdoped region are most likely incoherent phase fluctuations as found in hole-doped cuprates. At high temperatures, a large normal state Nernst signal is found at dopings from slightly underdoped to highly overdoped. Combined with normal state thermoelectric power, Hall effect and magnetoresistance measurements, the large Nernst effect is compatible with two-band model. For the highly overdoped films, the large Nernst effect is anomalous and not explainable with a simple hole-like Fermi surface seen in photoemission experiments.