Temperature-dependent valence state within the metallic phase of BaV10 O15 probed by hard x-ray photoelectron spectroscopy

S. Dash, M. Okawa, T. Kajita, T. Yoshino, R. Shimoyama, K. Takahashi, Y. Takahashi, R. Takayanagi, T. Saitoh, A. Yasui, E. Ikenaga, N. L. Saini, T. Katsufuji, T. Mizokawa

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Abstract

We have studied electronic properties of BaV10O15 in the intermediate-temperature phase as well as in the high-temperature metallic phase by using hard x-ray photoemission spectroscopy (HAXPES). The V 2p HAXPES show a shift in the high-temperature phase between 300 and 245 K which is similar to the shift of spectral weight near the Fermi edge. The binding energy of the O 1s HAXPES peak does not change except a slight shift of the lower binding energy edge in the opposite direction between 300 and 180 K across the transition to the intermediate-temperature phase. This behavior is in sharp contrast to the transition to the low-temperature insulating phase where V 2p and O 1s HAXPES show dramatic shifts in the same direction. This indicates that the charge-orbital change in the intermediate-temperature phase is driven by the correlated V 3d electrons and is electronic. The V2.5+-V2.5+ bond ordering is related to the metallic contribution and gradually decreases with cooling from 300 K. The valence-band HAXPES show the metallic features of the pseudogap behavior near the Fermi edge in and above the intermediate-temperature phase due to V2.5+-V3+ charge fluctuation. The magnitude of the pseudogap increases from 300 to 180 K in parallel with the gradual breaking of the V2.5+-V2.5+ bond and formation of trimers.

Original languageEnglish
Article number035122
JournalPhysical Review B
Volume99
Issue number3
DOIs
Publication statusPublished - 2019 Jan 11

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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    Dash, S., Okawa, M., Kajita, T., Yoshino, T., Shimoyama, R., Takahashi, K., Takahashi, Y., Takayanagi, R., Saitoh, T., Yasui, A., Ikenaga, E., Saini, N. L., Katsufuji, T., & Mizokawa, T. (2019). Temperature-dependent valence state within the metallic phase of BaV10 O15 probed by hard x-ray photoelectron spectroscopy. Physical Review B, 99(3), [035122]. https://doi.org/10.1103/PhysRevB.99.035122