  Microscopic mechanism for the Rashba-type band splitting is examined in
detail. We show how asymmetric charge distribution is formed when local orbital
angular momentum (OAM) and crystal momentum get interlocked due to surface
effects. An electrostatic energy term in the Hamiltonian appears when such OAM
and crystal momentum dependent asymmetric charge distribution is placed in an
electric field produced from an inversion symmetry breaking (ISB). Analysis by
using an effective Hamiltonian shows that, as the atomic spin-orbit coupling
(SOC) strength increases from weak to strong, originally OAM-quenched states
evolve into well-defined chiral OAM states and then to total angular momentum
J-states. In addition, the energy scale of the band splitting changes from
atomic SOC energy to electrostatic energy. To confirm the validity of the
model, we study OAM and spin structures of Au(111) system by using an effective
Hamiltonian for the d-orbitals case. As for strong SOC regime, we choose
Bi2Te2Se as a prototype system. We performed circular dichroism angle resolved
photoemission spectroscopy experiments as well as first-principles
calculations. We find that the effective model can explain various aspects of
spin and OAM structures of the system.
