Temperature-dependent angle-resolved photoemission spectroscopy study of the Ce 4f states in a possible topological Kondo insulator CeRhAs

The electronic structure of a possible topological Kondo insulator of CeRhAs has been investigated by employing temperature (T)-dependent angle-resolved photoemission spectroscopy (ARPES). Fermi surfaces (FSs) and band structures are successfully measured for three orthogonal crystallographic planes. The measured Fermi-edge states are found to have a three-dimensional (3D) character, contradictory to the proposed topological surface states of the 2D character. The measured FSs due to the Ce 4f electrons agree well with those from the density functional theory band structures unfolded into the reduced Ce-only unit cell. The theoretically predicted hourglass-type bulk bands along (X) over bar(S) over bar(X) over bar are not clearly resolved, in spite of the evident existence of those band features. T-dependent ARPES measurements reveal that the coherent Ce 4f states, having two pseudogap structures of Delta(1) similar to 80 meV and Delta(2) similar to 30 meV, persist to remain above 200 K, in agreement with the high Kondo temperature of CeRhAs.