Hard X-ray core-level photoemission of V2O3

• Published in: Europhysics letters 2004-11, Vol.68 (4), p.557-563
• Main Authors: Kamakura, N, Taguchi, M, Chainani, A, Takata, Y, Horiba, K, Yamamoto, K, Tamasaku, K, Nishino, Y, Miwa, D, Ikenaga, E, Awaji, M, Takeuchi, A, Ohashi, H, Senba, Y, Namatame, H, Taniguchi, M, Ishikawa, T, Kobayashi, K, Shin, S
• Format: Article
• Language: English
• ISSN: 0295-5075; 1286-4854
• DOI: 10.1209/epl/i2004-10240-4

We study the Mott-Hubbard metal-insulator transition in single-crystal V2O3 using hard X-ray (HX: hnu = 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: hnu = 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.