Core-Level Photoemission Study on Temperature-Induced Valence Transition of Eu Compounds

2014 Fiscal Year Final Research Report

• Project/Area Number: 24540381
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Condensed matter physics II
• Research Institution: Osaka Prefecture University
• Principal Investigator: MIMURA Kojiro 大阪府立大学, 工学(系)研究科(研究院), 准教授 (40305652)
• Co-Investigator(Kenkyū-buntansha): UOZUMI Takayuki 大阪府立大学, 大学院工学研究科, 教授 (80295724) ; MITSUDA Akihiro 九州大学, 理学研究院, 准教授 (20334708)
• Co-Investigator(Renkei-kenkyūsha): SATO Hitoshi 広島大学, 放射光科学研究センター, 准教授 (90243550)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 強相関電子系 / 価数転移 / 物性実験 / 物性理論 / 光物性

Outline of Final Research Achievements

Electronic structures of EuNi2(Si1-xGex)2 have been investigated by hard x-ray photoemission spectroscopy (HAXPES), in order to understand the temperature-induced valence transition of this system. The temperature-dependent HAXPES spectra clearly showed the valence transition with abrupt changes in the divalent and trivalent Eu 3d components. The Eu 3d spectral shape, especially the drastic change in trivalent Eu 3d feature with temperature, could not reproduced by the atomic calculation. Therefore, we have done calculations based on the Anderson model in which the hybridization of the trivalent Eu 4f electrons with the conduction electrons Vcf and the charge transfer energy Δ are taken into account. This result suggests that many-body effect between Eu 4f and conduction electrons is essential to understand the temperature-induced valence transition of this system. Our spectral analyses revealed, furthermore, that Vcf is one of the key parameters to govern the valence transition.

Free Research Field

固体光物性