We have performed angle-resolved photoemission spectroscopy (ARPES) on CeBi which undergoes a two-step antiferromagnetic (AF) transition with temperature. Soft-x-ray ARPES has revealed the inverted band structure at the X point of bulk Brillouin zone for CeBi (and also for LaBi) as opposed to LaSb with non-inverted band structure. Low-energy ARPES on CeBi has revealed the Dirac-cone band at the Gamma point in the paramagnetic phase associated with the bulk band inversion. On the other hand, a double Dirac-cone band appears on entering the first AF phase at T = 25 K, whereas a single Dirac-cone band recovers below the second AF transition at T = 14 K. The present result suggests an intricate interplay between antiferromagnetism and topological surface states in CeBi.
@article{arxiv.1910.00787,
title = {Unusual change in the Dirac-cone energy band upon two-step magnetic transition in CeBi},
author = {Hikaru Oinuma and Seigo Souma and Kosuke Nakayama and Koji Horiba and Hiroshi Kumigashira and Makoto Yoshida and Akira Ochiai and Takashi Takahashi and Takafumi Sato},
journal= {arXiv preprint arXiv:1910.00787},
year = {2019}
}