Single-crystal growth and physical property characterization of the intermediate-valence compound YbFe2Al10

We report single-crystal growth and physical property characterization of YbFe2Al10 compounds. The measurements of resistivity, magnetic susceptibility, and specific heat show different behaviors from previous studies on polycrystalline samples. An intermediate-valence characteristic with moderate mass enhancement is indicated. In particular, the optical spectroscopy measurement reveals formation of multiple hybridization energy gaps which become progressively pronounced at low temperature. The multiple hybridization energy gaps are likely caused by the hybridizations between the flat band from Yb 4f electrons and different bands of conduction electrons.National Science Foundation of China [11327806, GZ1123]; National Key Research and Development Program of China [2016YFA0300902]SCI(E)ARTICLE239