Title: Three-dimensional band structure of LaSb and CeSb:Absence of band inversion,
Abstract: We have performed angle-resolved photoemission spectroscopy (ARPES) of LaSb
and CeSb, a candidate of topological insulator. Using soft-x-ray photons, we
have accurately determined the three-dimensional bulk band structure and
revealed that the band inversion at the Brillouin-zone corner - a prerequisite
for realizing topological-insulator phase - is absent in both LaSb and CeSb.
Moreover, unlike the ARPES data obtained with soft-x-ray photons, those with
vacuum ultraviolet (VUV) photons were found to suffer significant $k_z$
broadening. These results suggest that LaSb and CeSb are topologically trivial
semimetals, and unusual Dirac-cone-like states observed with VUV photons are
not of the topological origin.