Point contact spectroscopy of Pr$_{2-x}$Ce$_x$CuO$_4$ in high magnetic fields

TL;DR

This study uses point contact spectroscopy to investigate the normal state density of states in electron-doped Pr$_{2-x}$Ce$_x$CuO$_4$ under high magnetic fields, revealing a persistent anomalous gap that challenges the pseudogap analogy.

Contribution

It provides new insights into the normal state gap in electron-doped cuprates and proposes an alternative explanation involving surface disorder and electron correlations.

Findings

Normal state gap persists up to 31 T magnetic field.

The gap's nature differs from the pseudogap in hole-doped cuprates.

Surface disorder and electron correlations may cause the observed gap.

Abstract

We have studied the density of states of the normal state of the electron-doped superconductor Pr$_{2-x}$Ce$_x$CuO$_4$ at low temperatures and in magnetic fields up to 31 Tesla using point contact spectroscopy on single crystals. Our data clearly reveal an anomalous gap in the normal state density of states. This normal state gap survives even in the highest applied field of 31 T. Our results cast doubt over whether this gap found in electron-doped cuprates is the analog of the pseudogap in hole-doped cuprates. We have suggested an alternate origin of the normal state gap, which involves the effect of disorder and electron correlations at the surface of cuprates.