Three-dimensional bulk band dispersion in polar BiTeI with giant Rashba-type spin splitting
M. Sakano, J. Miyawaki, A. Chainani, Y. Takata, T. Sonobe, T. Shimojima, M. Oura, S. Shin, M. S. Bahramy, R. Arita, N. Nagaosa, H. Murakawa, Y. Kaneko, Y. Tokura, K. Ishizaka
Abstract
In layered polar semiconductor BiTeI, giant Rashba-type spin-split band dispersions show up due to the crystal structure asymmetry and the strong spin-orbit interaction. Here we investigate the 3-dimensional (3D) bulk band structures of BiTeI using the bulk-sensitive
hν
-dependent soft x-ray angle resolved photoemission spectroscopy (SX-ARPES). The obtained band structure is shown to be well reproducible by the first-principles calculations, with huge spin splittings of
∼300
meV at the conduction-band-minimum and valence-band-maximum located in the
k
z
=π/c
plane. It provides the first direct experimental evidence of the 3D Rashba-type spin splitting in a bulk compound.