[15p-A409-1~11] 6.3 Oxide electronics

△ [15p-A409-2] Electronic Phase Diagram of Cr-Doped VO₂ Epitaxial Films Studied by in situ Photoemission Spectroscopy

〇Daisuke Shiga^1,2, Xianglin Cheng¹, Taehyun Kim¹, Tatsuhiko Kanda^1,2, Naoto Hasegawa¹, Miho Kitamura², Kohei Yoshimatsu¹, Hiroshi Kumigashira^1,2 (1.IMRAM, Tohoku Univ., 2.IMSS, KEK)

Keywords:strongly correlated electron system, metal-insulator transition, photoelectron spectroscopy

VO₂ exhibits an abrupt electronic phase transition driven by the cooperation of strong electron correlation and collective V-V dimerization. We have previously reported a complicated electronic phase diagram of Cr:VO₂ films. To clarify its origin, we investigated the electronic structures of Cr:VO₂ films via synchrotron radiation spectroscopy. The spectroscopic observations suggest that the Cr³⁺ substitution suppresses the collective V-V dimerization for Cr:8at%. However, the V 3d states and energy gap at the Fermi level are essentially unchanged. These results conclude that the electronic phase transition in Cr:VO₂ is a V-V dimerization-assisted Mott transition. On the other hand, a Mott gap is formed for Cr:>8at%. These results suggest that the Mott insulating phase without the dimerization is stabilized at Cr:>8at% as a result of the superiority of the Mott instability over the Peierls one.