Charge-Orbital Ordering and Verwey Transition in Magnetite Measured by Resonant Soft X-Ray Scattering

We report experimental evidence for the charge-orbital ordering in magnetite below the Verwey transition temperature $T_{\mathrm{V}}$. Measurements of O $K$-edge resonant x-ray scattering on magnetite reveal that the O $2p$ states in the vicinity of the Fermi level exhibit a charge-orbital ordering along the $c$ axis with a spatial periodicity of the doubled lattice parameter of the undistorted cubic phase. Such a charge-orbital ordering vanishes abruptly above $T_{\mathrm{V}}$ and exhibits a thermal hysteresis, correlating closely with the Verwey transition in magnetite.