Electronic states of magnetite from photoemission spectroscopy ARUPS

Abstract

The valence band photoemission spectra of epitaxially grown film and bulk single crystal of magnetite were measured by the angle-resolved ultraviolet photoemission spectroscopy (ARUPS) at 300 K and 120 K. Four main features of the electron photoemission were observed at about -1.0 eV, -3.5 eV, -5.0 eV and -6.5 eV below the chemical potential; they are rather strongly dependant on structure and preparation of surface. The three higher-energy features showed significant energy dispersion. The ARUPS spectra were compared to the accessible band structure calculations. Special attention was paid to the leading edge of the emission at -1.0 eV of the low-temperature spectrum where an insulating gap should be observed.

Photoemission electronic states of epitaxially grown magnetite films

“…1. The lower BE part with the pronounced emissions at −1.0, −3.0 and −5.5 eV [21] is dominated by the Fe 3d states, as is clear from band structure calculations [3,4,6]. The terminationsensitive part from −7 to −12 eV is mainly due to 2p oxygen states with some contribution from Fe 3d states [3,4,6].…”

Surface Structural Evolution in Iron Oxide Thin Films

“…In addition, the intensity of the peak at ∼3.8 eV is obviously decreased after oxidation at 800 K (compared with curve b), and an observable peak at ∼2.7 eV appears that is associated with the decrease in 3d 5 electronic configurations due to the partial reduction of the Fe 3+ state . For Fe 3 O 4 (111), the 3d emission consists of two final-state spin configurations of 3d 5 out of the Fe 2+ (3d 6 ) initial state and one quintet final-state spin configuration of 3d 4 out of the Fe 3+ (3d 5 ) initial state . Thus, the presence of characteristic valence band peaks of Fe 2+ (within 1.0 eV) and Fe 3+ states (∼2.7 eV) in UP spectra also provides evidence of the evolution of the chemical states of iron.…”

Photoemission band structure of La0.7(Ca, Ce)0.3MnO3 thin films and a La0.9Ca0.1CoO3 crystal

“…ARUPS spectra for the La 0.9 Ca 0.1 CoO 3 close to the Fermi energy on expanded scale. The inset shows an example of the low-energy emission and the way how to extract a gap E g according to [23,24] (see the text). position.…”

“…Following the procedure in the papers [23,24] the spectral onset below 0 eV was defined as the intersection of the leading edge with the zero intensity base line (see the inset on Fig. 2).…”