Direct observation of t2g orbital ordering in magnetite

TL;DR

This study provides direct experimental evidence of t2g orbital and charge ordering in magnetite below the Verwey transition using soft-x-ray diffraction, clarifying the microscopic origin of its low-temperature phase.

Contribution

It is the first direct observation of t2g orbital ordering in magnetite, revealing the microscopic mechanism behind the Verwey transition.

Findings

Evidence of orbital ordering at Fe2+ sites

Identification of charge modulation in magnetite

Confirmation of t2g orbital ordering as the cause of diffraction peaks

Abstract

Using soft-x-ray diffraction at the site-specific resonances in the Fe L23 edge, we find clear evidence for orbital and charge ordering in magnetite below the Verwey transition. The spectra show directly that the (001/2) diffraction peak (in cubic notation) is caused by t2g orbital ordering at octahedral Fe2+ sites and the (001) by a spatial modulation of the t2g occupation.