High-resolution photoemission study of CeLaRhAs; A Collapse of the energy gap in the Kondo semiconductor

Shimada, Kenya*; Higashiguchi, Mitsuharu*; Fujimori, Shinichi   ; Saito, Yuji  ; Fujimori, Atsushi; Namatame, Hirofumi*; Taniguchi, Masaki*; Sasakawa, Tetsuya*; Takabatake, Toshiro*

High-resolution resonance-photoemission spectroscopy has been performed on the CeLaRhAs (0x0.05) single crystal to elucidate a collapse of the energy gap in the Kondo semiconductor CeRhAs by La substitution. With increasing x, the spectral intensity of the Ce 4f derived states near the Fermi level decreases and new 4f derived spectral feature appears at a higher binding energy. The Rh 4d-derived states, on the other hand, are not significantly changed by the substitution. New 4f-derived states have incoherent nature, which is responsible for the collapse of the semiconducting state for x0.02.