Journal Article Temperature Dependence of Magnetically Active Charge Excitations in Magnetite across the Verwey Transition

Taguchi, M.  ,  Chainani, A.  ,  Ueda, S.  ,  Matsunami, M.  ,  Ishida, Y.  ,  Eguchi, R.  ,  Tsuda, S.  ,  Takata, Y.  ,  Yabashi, M.  ,  Tamasaku, K.  ,  Nishino, Y.  ,  Ishikawa, T.  ,  Daimon, H.  ,  Todo, S.  ,  Tanaka, H.  ,  Oura, M.  ,  Senba, Y.  ,  Ohashi, H.  ,  Shin, S.

2015-12-17 , American Physical Society
We study the electronic structure of bulk single crystals and epitaxial films of Fe3O4. Fe 2p core level spectra show clear differences between hard x-ray (HAX) and soft x-ray photoemission spectroscopy (PES). The bulk-sensitive spectra exhibit temperature (T) dependence across the Verwey transition, which is missing in the surface-sensitive spectra. By using an extended impurity Anderson full-multiplet model-and in contrast to an earlier peak assignment-we show that the two distinct Fe species (A and B site) and the charge modulation at the B site are responsible for the newly found double peaks in the main peak above TV and its T-dependent evolution. The Fe 2p HAXPES spectra show a clear magnetic circular dichroism (MCD) in the metallic phase of magnetized 100-nm-thick films. The model calculations also reproduce the MCD and identify the contributions from magnetically distinct A and B sites. Valence band HAXPES shows a finite density of states at EF for the polaronic half metal with a remnant order above TV and a clear gap formation below TV. The results indicate that the Verwey transition is driven by changes in the strongly correlated and magnetically active B-site electronic states, consistent with resistivity and optical spectra.

Number of accesses :  

Other information