Hard X-ray core-level photoemission of V 2 O 3

Autor: T. Ishikawa, N. Kamakura, Yoshinori Nishino, H. Namatame, Keiichiro Yamamoto, Munetaka Taguchi, Eiji Ikenaga, Daigo Miwa, Masaki Taniguchi, Haruhiko Ohashi, Ashish Chainani, K. Horiba, Shik Shin, Kenji Tamasaku, Y. Takata, Mitsuhiro Awaji, A. Takeuchi, Yasunori Senba, Kensuke Kobayashi
Rok vydání: 2004
Předmět:
Zdroj: Europhysics Letters (EPL). 68:557-563
ISSN: 1286-4854
0295-5075
Popis: We study the Mott-Hubbard metal-insulator transition in single-crystal V2O3 using hard X-ray (HX: hν = 5940 eV) core-level photoemission spectroscopy (PES). HX-PES enables a bulk probe of the electronic structure in the paramagnetic metallic and antiferromagnetic insulating phases. Metallic V2O3 shows additional features at low binding energy to the main peak of V 1s, 2p, and 3s core levels, which vanish in the insulating phase. The low-binding-energy features in the metallic phase are also observed using soft X-rays (SX: hν = 1450 eV), but with a reduced relative intensity compared to the HX-PES spectrum. A model cluster calculation including core hole screening by coherent states at the Fermi level, reproduces the low-binding-energy features in the metallic phase. The O 1s core level also shows spectral changes: the asymmetric line shape in the metallic phase transforms to a symmetric line shape in the insulating phase, consistent with the metal-insulator transition. The results indicate screening by coherent states is more effective in the bulk compared to the surface. HX-PES is, thus, a reliable probe of the electronic-structure changes across the metal-insulator transition in strongly correlated electron systems.
Databáze: OpenAIRE