Jahn-Teller stabilization of a "polar" metal oxide surface: Fe3O4(001)

TL;DR

This study uses ab initio thermodynamics and x-ray diffraction to identify a stable polar surface termination of Fe3O4(001), revealing significant electronic and magnetic property changes.

Contribution

It uncovers a previously ignored polar surface structure of Fe3O4(001) stabilized by Jahn-Teller effects, confirmed experimentally and characterized electronically.

Findings

Identified a stable polar surface termination over a range of conditions

Confirmed the structure with x-ray diffraction

Observed a halfmetal-to-metal transition in electronic properties

Abstract

Using ab initio thermodynamics we compile a phase diagram for the surface of Fe3O4(001) as a function of temperature and oxygen pressures. A hitherto ignored polar termination with octahedral iron and oxygen forming a wave-like structure along the [110]-direction is identified as the lowest energy configuration over a broad range of oxygen gas-phase conditions. This novel geometry is confirmed in a x-ray diffraction analysis. The stabilization of the Fe3O4(001)-surface goes together with dramatic changes in the electronic and magnetic properties, e.g., a halfmetal-to-metal transition.