Origin of superconductivity in hole doped SrBiO3 bismuth oxide perovskite from parameter-free first-principles simulations

TL;DR

This study demonstrates that parameter-free DFT simulations can accurately model superconductivity in SrBiO3-based oxides, revealing the pairing mechanism and phase transitions without needing strong correlation methods.

Contribution

It shows that standard DFT can effectively predict superconducting properties and phase behavior in complex oxides, challenging the notion that strong correlations are always necessary.

Findings

DFT captures the insulating to metallic transition with doping.

Electron-phonon coupling constant matches experimental data.

Proximity to a disproportionated phase is key for superconductivity.

Abstract

The recent discovery nickel oxides superconductors have highlighted the importance of first-principles simulations for understanding the formation of the bound electrons at the core of superconductivity. Nevertheless, superconductivity in oxides is often ascribed to strong electronic correlation effects that Density Functional Theory (DFT) cannot properly take into account, thereby disqualifying this technique. Being isostructural to nickel oxides, Sr1-xKxBiO3 superconductors form an ideal testbed for unveiling (i) the lowest theory level needed to model complex superconductors and (ii) the underlying pairing mechanism yielding superconductivity. Here I show that parameter-free DFT simulations capture all the experimental features and related quantities of Sr1-xKxBiO3 superconductors, encompassing the prediction of an insulating to metal phase transition upon increasing the K doping content and of an electron-phonon coupling constant of 1.22 in sharp agreement with the experimental value of 1.3 +/- 0.2. Proximity of a disproportionated phase is further demonstrated to be a prerequisite for superconductivity in bismuthates. This work highlights that appropriately executed DFT is a sufficient platform for studying superconductivity in complex oxides.