Electronic structure of Fe3O4 across the Verwey transition

A study of the first-order Verwey transition in single-crystal Fe3O4 using high-resolution temperature dependent (100 - 300K) photoemission spectroscopy is reported, Fe3O4 exhibits a gap of similar to 70 meV in the occupied part of the density of states(DOS) below the transition temperature, Tv = 122 K. On increasing the temperature above Tv, the gap in the DOS is closed thus establishing a metal-semiconductor transition. The Fe 3d derived features arising from Fe3+ (ep(2)) majority and Fe2+ (t2g(1)) minority spin states responsible for the transition, retain their character just above the transition but merge into a single feature by 300 K. Simultaneously, the DOS at EF increases systematically in the metallic phase. The results indicate a gradual change in the short-range order for T > Tv which gives rise to the non-metallic like electrical conductivity observed just above Tv.