Oxygen K-edge shift at the Verwey transition of magnetite

The temp. dependence of the O K-edge threshold has been investigated in a temp. range encompassing the Verwey transition. Both above and below TV the O K-edge threshold changes linear with temp. whereas there is discontinuous energy shift of 13 meV at TV. A comparison of our results to published low and high energy photoemission expts. suggests the presence of an asym. gap with respect to the Fermi level. This explains present fundamental differences between photoemission and IR derived gap energies, and supports the polaronic image of the elec. cond. of Fe3O4 above the Verwey transition temp. [on SciFinder (R)]