Strongly spin-orbit coupled two-dimensional electron gas emerging near   the surface of polar semiconductors
  We investigate the two-dimensional (2D) highly spin-polarized electron accumulation layers commonly appearing near the surface of n-type polar semiconductors BiTeX (X = I, Br, and Cl) by angular-resolved photoemission spectroscopy. Due to the polarity and the strong spin-orbit interaction built in the bulk atomic configurations, the quantized conduction-band subbands show giant Rashba-type spin-splitting. The characteristic 2D confinement effect is clearly observed also in the valence-bands down to the binding energy of 4 eV. The X-dependent Rashba spin-orbit coupling is directly estimated from the observed spin-split subbands, which roughly scales with the inverse of the band-gap size in BiTeX. 
M. Sakano, M. S. Bahramy, A. Katayama, T. Shimojima, H. Murakawa, Y.   Kaneko, W. Malaeb, S. Shin, K. Ono, H. Kumigashira, R...
cond-mat.mtrl-sci