Enhancement of superconductivity in electron-hole coexisting Sr$_{1-x}$Eu$_{x}$CuO$_{2+y}$ films

TL;DR

This study demonstrates that moderate coexistence of electrons and holes in Sr$_{1-x}$Eu$_{x}$CuO$_{2+y}$ films enhances superconductivity, revealing a two-dimensional nature and altered vortex dynamics, offering insights into high-temperature superconductivity.

Contribution

It provides the first experimental evidence that electron-hole coexistence can enhance superconductivity in cuprate films, with detailed transport measurements and analysis.

Findings

Superconductivity is enhanced by electron-hole coexistence.

Superconductivity shows a two-dimensional nature with ~5.2 nm thickness.

Electron-hole coexistence affects vortex activation energy and dynamics.

Abstract

We report transport measurements of infinite-layer cuprate Sr$_{1-x}$Eu$_{x}$CuO$_{2+y}$ films with controlled electron (by trivalent europium) and hole (by interstitial apical oxygen) carriers grown on SrTiO$_3$(001) with molecular beam epitaxy. An unusual enhancement of superconductivity upon moderate electron-hole coexistence in the films is found, which spans over the whole superconducting phase diagram and becomes more prominent in the underdoped regime. The superconductivity exhibits a two-dimensional nature with a thickness of approximately 5.2 nm, irrespective of the varying carriers, confirmed by angle-resolved magnetoresistance measurements and the Berzzinsky-Kosterlitz-Thouless transition. Nevertheless, the electron-hole coexistence enlarges the thermal activation energy of vortex motion that deviates obviously from the usual logarithmic evolution with the magnetic field. Our results offer a promising perspective to understand and enhance the high-temperature superconductivity in cuprates.