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

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

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Abstract

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.

Original languageEnglish
Article number256405
JournalPhysical Review Letters
Volume115
Issue number25
DOIs
Publication statusPublished - Dec 17 2015
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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    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). Temperature Dependence of Magnetically Active Charge Excitations in Magnetite across the Verwey Transition. Physical Review Letters, 115(25), [256405]. https://doi.org/10.1103/PhysRevLett.115.256405