  We propose that existence of local orbital angular momentum (OAM) on the
surfaces of high-Z materials play a crucial role in the formation of
Rashba-type surface band splitting. Local OAM state in a Bloch state produces
asymmetric charge distribution (electric dipole). Presence of surface electric
field aligns the electric dipole and results in chiral OAM states and the
relevant Rashba- type splitting. Therefore, the band splitting originates from
electric dipole interaction, not from the Zeeman splitting as proposed in the
original Rashba picture. The characteristic spin chiral structure of Rashba
states is formed through the spin-orbit coupling and thus is a secondary effect
to the chiral OAM. Results from first principles calculations on a single Bi
layer under an external electric field verify the key predictions of the new
model, including the direction of the spin textures which is predicted to be in
opposite direction in the Rashba picture.
