Charge-gap formation upon the Verwey transition inFe3O4

Abstract

The temperature-dependent electronic structure has been investigated for a single crystal of magnetite $\left({\mathrm{Fe}}_3{\mathrm{O}}_4\right)$ by measurements of the optical-conductivity spectrum. Upon the charge-ordering (Verwey) transition ${(T}_V=121\mathrm{}\hspace{0.5em}\mathrm{K})$, a clear opening of the optical gap (0.14 eV) is observed. Above $T_V,$ the optical conductivity spectra shows notable spectral weight transfer in the $\mathrm{Fe}\hspace{0.5em}3d$ intersite transition region $\left(0\mathrm{}-2\hspace{0.5em}\mathrm{eV}\right)$, while preserving the pseudogap or polaronic feature, indicating highly diffuse charge dynamics.