Temperature-induced valence transition in EuNi2(Si1–xGex)2 investigated by high-energy resolution fluorescence detection X-ray absorption spectroscopy. (October 2020)

• Record Type: Journal Article
• Authors: Shimokasa, Ryohei; Kawamura, Naomi; Matsumoto, Takayuki; Kawakami, Koki; Kawabata, Taku; Isumi, Gen; Uozumi, Takayuki; Mitsuda, Akihiro; Wada, Hirofumi; Mizumaki, Masaichiro; Mimura, Kojiro
• Is Part Of: Radiation physics and chemistry. Volume 175(2020:Oct.)
• Publication Date: 2020-10
• Subjects: EuNi2(Si1–xGex)2 -- Temperature-induced valence transition -- c-f hybridization -- High-energy resolution fluorescence detection -- X-ray absorption spectroscopy; Radiation chemistry -- Periodicals; Radiometry -- Periodicals; Radiation -- Periodicals; Chimie sous rayonnement -- Périodiques; 539.2
• DOI: 10.1016/j.radphyschem.2019.02.009
• Languages: English
• ISSNs: 0969-806X

Abstract

Abstract: Electronic structures of the temperature-induced valence transition system EuNi2 (Si1– x Ge x )2 with x = 0.70, 0.79, 0.82 have been investigated by means of high-energy resolution fluorescence detection X-ray absorption spectroscopy (HERFD-XAS). The HERFD-XAS spectra clearly change their intensities of Eu 2+ and Eu 3+ components which directly reflect the temperature-induced valence transition. For x = 0.70, gradual spectral change exhibits a continuous valence transition, while drastic changes for x = 0.79 and 0.82 indicate first-order valence transitions. High-energy resolution measurements made it possible to observe additional fine structures which are recognized more clearly below the transition temperature. Existence of these fine structures suggests that many-body effect plays an important role in the temperature-induced valence transition of this system. The variation of Eu mean valence estimated from the HERFD-XAS spectra for each x correlates with that of magnetic susceptibility. Highlights: Valence transition of EuNi2 (Si1- x Ge x )2 proved by means of Eu L 3 HERFD-XAS. Temperature-dependent fine structures reminiscent of change in many-body interaction through the valence transition. Variation of Eu valence through the valence transition is associated with that of magnetic states.