Re-examining the Verwey transition in Fe3O4

TL;DR

This paper uses advanced computational methods to show that the Verwey transition in Fe3O4 is primarily driven by multi-orbital electronic correlations and Jahn-Teller distortions, rather than simple charge ordering.

Contribution

It demonstrates that the Verwey transition is mainly caused by electronic correlations and lattice distortions, challenging the traditional charge order perspective.

Findings

Charge order has minimal effect on low-temperature spectral function.

The charge gap and resistivity jump are reproduced only when charge order is included.

The transition is driven by multi-orbital correlations and Jahn-Teller distortions.

Abstract

Motivated by recent structural data questioning the adequacy of the charge order (CO)/disorder picture for the Verwey transition (at T=T_V) in magnetite, we re-investigate this issue within a new theoretical picture. Using the state-of-the-art LDA+DMFT method, we show that the non-trivial interplay between the B-site octahedral distortions and strong, multi-orbital electronic correlations in the half-metallic state is a necessary ingredient for a proper quantitative understanding of the physical responses across T_V. While weak CO is found to have very small effects on the low-T spectral function, the low-T charge gap and the resistivity jump across T_V are quantitatively reproduced only upon inclusion of CO in LSDA+DMFT scheme. Our results strongly suggest that the Verwey transition is dominantly driven by multi-orbital electronic correlations with associated JT distortions on the B-sublattice, and constitutes a non-trivial advance in attempts to understand the physics of Fe3O4.