Photoemission Study of Fe₃O₄

Abstract

Photoemission experiment was carried out on a (100) surface of Fe₃O₄ at room temperature, for the incident photon energies between 30.5 and 140 eV, and the results were compared with the band structure calculated by APW method (J. Phys. Soc. Jpn. 53 (1984) 312). Peaks due to the Fe(3d)–O(2p) valence band, O(2s) band, Fe(3p) band and Auger electrons were observed. Valence band emission starts from the Fermi level indicating that Fe₃O₄ is a “metal”, not an “insulator with electron diffusion”. Several peaks are distinguished in angle-resolved normal emission spectra in the valence band region. Other peaks are broad and do not show any structure. As a whole, applicability of the calculated band structure is proved. Resonant enhancement of photoemission is observed near the Fe(3p) core excitation region. Two subsidiary peaks at 7.5 and 11 eV are tentatively assigned to satellites due to a singlet and a triplet hole pair, respectively. Correlation energy between 3d electrons is estimated from the satellite position and the kinetic energy of Auger electrons.