Electronic structure of correlated topological insulator candidate YbB₆ studied by photoemission and quantum oscillation

Angle-resolved photoemission spectroscopy (ARPES) and torque magnetometry (TM) measurements have been carried out to study the electronic structures of a correlated topological insulator (TI) candidate YbB₆. We observed clear surface states on the [001] surface centered at the Γ and M points of the surface Brillouin zone. Interestingly, the fermiology revealed by the quantum oscillation of TM measurements agrees excellently with ARPES measurements. Moreover, the band structures we observed suggest that the band inversion in YbB₆ happens between the Yb_5d and B_2p bands, instead of the Yb_5d and Yb_4f bands as suggested by previous theoretical investigation, which will help settle the heavy debate regarding the topological nature of samarium/ytterbium hexaborides.