Angle-resolved photoemission spectroscopy of the low-energy electronic structure of superconducting Pr$_2$CuO$_4$ driven by oxygen non-stoichiometry

TL;DR

This study uses angle-resolved photoemission spectroscopy to investigate the low-energy electronic structure of superconducting Pr$_2$CuO$_4$ thin films, revealing that electron concentration, not Ce doping, governs superconductivity.

Contribution

It demonstrates that the electronic structure of Ce-free Pr$_2$CuO$_4$ is similar to Ce-doped crystals, emphasizing the role of oxygen non-stoichiometry in superconductivity.

Findings

Fermi surface similar to Ce-doped crystals

Electron concentration crucial for superconductivity

Oxygen non-stoichiometry influences electronic states

Abstract

Bulk crystals of electron-doped cuprates with the T'-type structure require both Ce substitutions and reduction annealing for the emergence of superconductivity while the reduction annealing alone can induce superconductivity in thin films of the T'-type cuprates. In order to reveal low-energy electronic states which are responsible for the superconductivity, we have conducted angle-resolved photoemission spectroscopy measurements on thin films of the superconducting Ce-free T'-type cuprate Pr$_2$CuO$_4$. The results indicate that the overall band structure and the Fermi surface area of the superconducting Pr$_2$CuO$_4$ are similar to those of superconducting Ce-doped bulk single crystals, highlighting the importance of the actual electron concentration rather than the Ce concentration when discussing the physical properties of the T'-type cuprates.