Verwey transition inFe3O4investigated usingLDA+DMFT

Abstract

Motivated by recent structural data questioning the adequacy of the charge order (CO) or disorder picture for the Verwey transition (at $T={T}_{V}$) in magnetite, we reinvestigate this issue within a new theoretical picture. Using the local density $\text{approximation}+\text{dynamical}$ mean-field theory ($\mathrm{LDA}+\mathrm{DMFT}$) method, we show that the nontrivial interplay between octahedral distortions and strong, multiorbital 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 the local spin density $\text{approximation}+\mathrm{DMFT}$ scheme. Our results strongly suggest that the Verwey transition is dominantly driven by multiorbital electronic correlations with associated Jahn-Teller distortions on the $B$ sublattice, and constitutes a nontrivial advance in attempts to understand the physics of ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}$.