The enabling electronic motif for topological insulation in ABO3 perovskites and its structural stability

TL;DR

This paper identifies the electronic motif enabling topological insulation in ABO3 perovskites and explores the conditions for their structural stability, providing design principles for stable oxide topological insulators.

Contribution

It clarifies the design principles and conditions under which ABO3 perovskites can exhibit stable topological insulating behavior at ambient pressures.

Findings

Lone-pair electron-rich B atoms enable topological band inversion.

Atomic distortions can remove band inversion in poorly screened oxides.

Moderate pressure can stabilize the coexistence of topological and structural stability.

Abstract

Stable oxide topological insulators (TIs) that could bring together the traditional oxide functionalities with the dissipationless surface states of TIs have been sought for years but none was found. Yet, heavier chalcogenides (selenides, tellurides) were readily found to be TIs. We clarify here the basic contradiction between TI-ness and stability which is maximal for oxides, and trace the basic design principles necessary to identify the window of opportunity of stable TIs. We first identify the electronic motif that can achieve topological band inversion ("topological gene") in ABO3 as being a lone-pair electron-rich B atom (e.g. Te, I, Bi) at the octahedral site. We then illustrate that poorly screened oxide systems with large inversion energies can undergo energy-lowering atomic distortions that remove the band inversion. We identify the coexistence windows of TI functionality and structure stability for different pressures and find that the common cubic ABO3 structures have inversion energies lying outside this coexistence window at zero pressure but could be moved into the coexistence window at moderate pressures. Our study demonstrates the interplay between topological band inversion and structural stability and traces the basic principles needed to design stable oxide topological insulators at ambient pressures.