Stabilizing and Tuning Superconductivity in La$_3$Ni$_2$O$_{7-\delta}$ Films: Oxygen Recycling Protocol Reveals Hole-Doping Analogue

TL;DR

This study presents an oxygen recycling protocol to stabilize and tune superconductivity in La$_3$Ni$_2$O$_{7- heta}$ films, revealing oxygen content as an analogue to hole doping and enabling better control of superconducting properties.

Contribution

The paper introduces a novel oxygen recycling method that stabilizes superconductivity and demonstrates oxygen content as a hole-doping analogue in La$_3$Ni$_2$O$_{7- heta}$ films.

Findings

Oxygen removal and ozone-assisted annealing restore superconductivity.

Oxygen content acts as an analogue to hole doping via Sr substitution.

An electronic phase diagram highlights the doping mechanism.

Abstract

The recent achievement of superconductivity in La$_3$Ni$_2$O$_{7-\delta}$ with transition temperatures exceeding 40 K in thin films under compressive strain and 80 K in bulk crystals under high pressure opens new avenues for research on high-temperature superconductivity. The realization of superconductivity in thin films requires delicate control of growth conditions, which presents significant challenges in the synthesis process. Furthermore, the stability of superconducting La$_3$Ni$_2$O$_{7-\delta}$ films is compromised by oxygen loss, which complicates their characterization. We introduce an effective recycling protocol that involves oxygen removal in a precursor phase followed by ozone-assisted annealing, which restores superconducting properties. By tuning the oxygen content, we construct an electronic phase diagram that highlights oxygen addition as a potential analogue to hole doping via La substitution with Sr, providing insights into the doping mechanism and guiding future material optimization.