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arXiv · 1712.04113

Direct observation of heterogeneous valence state in Yb-based quasicrystalline approximants

M. Matsunami·M. Oura·K. Tamasaku·T. Ishikawa·S. Ideta·K. Tanaka·T. Takeuchi·T. Yamada·A. P. Tsai·K. Imura·K. Deguchi·N. K. Sato·T. Ishimasa
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Abstract

We study the electronic structure of Tsai-type cluster-based quasicrystalline approximants, Au$_{64}$Ge$_{22}$Yb$_{14}$ (AGY-I), Au$_{63.5}$Ge$_{20.5}$Yb$_{16}$ (AGY-II), and Zn$_{85.4}$Yb$_{14.6}$ (Zn-Yb), by means of photoemission spectroscopy. In the valence band hard x-ray photoemission spectra of AGY-II and Zn-Yb, we separately observe a fully occupied Yb 4$f$ state and a valence fluctuation derived Kondo resonance peak, reflecting two inequivalent Yb sites, a single Yb atom in the cluster center and its surrounding Yb icosahedron, respectively. The fully occupied 4$f$ signal is absent in AGY-I containing no Yb atom in the cluster center. The results provide direct evidence for a heterogeneous valence state in AGY-II and Zn-Yb.

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M. Matsunami, M. Oura, K. Tamasaku, T. Ishikawa, S. Ideta, K. Tanaka, T. Takeuchi, T. Yamada, A. P. Tsai, K. Imura, K. Deguchi, N. K. Sato, T. Ishimasa. 2017-12-12. Direct observation of heterogeneous valence state in Yb-based quasicrystalline approximants. https://doi.org/10.1103/physrevb.96.241102

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