Polarity induced electronic and atomic reconstruction at NdNiO2/SrTiO3 interfaces

TL;DR

This study uses computational methods to investigate how polar discontinuity causes electronic and atomic reconstruction at NdNiO2/SrTiO3 interfaces, revealing atomic reconstruction's inevitability and its potential impact on superconductivity.

Contribution

It demonstrates that atomic reconstruction occurs at the interface and proposes a configuration with residual oxygen affecting electronic states relevant to superconductivity.

Findings

Atomic reconstruction is unavoidable at the interface.

Residual oxygen influences electronic hybridization.

Atomic reconstruction may weaken superconductivity.

Abstract

Superconductivity has recently been observed in Sr-doped NdNiO2 films grown on SrTiO3. Whether it is caused by or related to the interface remains an open question. To address this issue, we use density functional theory calculation and charge transfer self-consistent model to study the effects of polar discontinuity on the electronic and atomic reconstruction at the NdNiO2/SrTiO3 interface. We find that sharp interface with pure electronic reconstruction only is energetically unfavorable, and atomic reconstruction is unavoidable. We further propose a possible interface configuration that contain residual apical oxygen. These oxygen atoms lead to hybrids of dz2 and dx2-y2 states at the Fermi level, which weaken the single-band feature and may be detrimental to superconductivity.