Emergence of high-temperature superconductivity at the interface of two Mott insulators

TL;DR

This study reports the discovery of high-temperature superconductivity at the interface between two Mott insulators, La2CuO4 and PrBa2Cu3O7, driven by oxygen redistribution and interface effects.

Contribution

It demonstrates for the first time HTS emergence at a Mott insulator-Mott insulator interface, expanding understanding of interfacial superconductivity mechanisms.

Findings

Superconductivity confined within two unit cells near the interface.

Superconductivity arises on the La2CuO4 side, not the PBCO side.

Oxygen redistribution plays a key role in enabling HTS.

Abstract

Interfacial superconductivity has manifested itself in various types of heterostructures: band insulator-band insulator, band insulator-Mott insulator, and Mott insulator-metal. We report the observation of high-temperature superconductivity (HTS) in a complementary and long expected type of heterostructures, which consists of two Mott insulators, La2CuO4 (LCO) and PrBa2Cu3O7 (PBCO). By carefully controlling oxidization condition and selectively doping CuO2 planes with Fe atoms, which suppress superconductivity, we found that the superconductivity arises at the LCO side and is confined within no more than two unit cells (about 2.6 nm) near the interface. A phenomenon of overcome the Fe barrier will show up if excess oxygen is present during growth. Some possible mechanisms for the interfacial HTS have been discussed, and we attribute it to the redistribution of oxygen.