d$_{xz/yz}$ subband structure and Chiral Orbital Angular Momentum of Nb doped SrTiO$_{3}$ surface states

Using angle resolved photoemission spectroscopy (ARPES), we investigate subband structure and chiral orbital angular momentum (OAM) texture on the surface of lightly electron doped SrTiO$_{3}$ single crystals. Our linearly polarized light ARPES data taken with 51 eV photons, reveal additional subbands for out-of-plane d$_{xz/yz\, }$orbitals in addition to the previously reported ones. Our CD-ARPES data reveal a chiral OAM structure which we use as a clue to explain the origin of linear Rashba-like surface band splitting of Ti 3d t$_{2g}$ orbitals. The observed CD signal is enhanced near crossing points, where different orbitals hybridize, compatible with a linear Rashba-like surface band splitting.