Photoelectron spin-polarization-control in the topological insulator   Bi2Se3
  We study the manipulation of the photoelectron spin-polarization in Bi$_2$Se$_3$ by spin- and angle-resolved photoemission spectroscopy. General rules are established that enable controlling the spin-polarization of photoemitted electrons via light polarization, sample orientation, and photon energy. We demonstrate the $\pm$100% reversal of a single component of the measured spin-polarization vector upon the rotation of light polarization, as well as a full three-dimensional manipulation by varying experimental configuration and photon energy. While a material-specific density-functional theory analysis is needed for the quantitative description, a minimal two-atomic-layer model qualitatively accounts for the spin response based on the interplay of optical selection rules, photoelectron interference, and topological surface-state complex structure. It follows that photoelectron spin-polarization control is generically achievable in systems with a layer-dependent, entangled spin-orbital texture. 
Z.-H. Zhu, C.N. Veenstra, S. Zhdanovich, M.P. Schneider, T. Okuda, K.   Miyamoto, S.-Y. Zhu, H. Namatame, M. Taniguchi, M.W....
cond-mat.mtrl-sci cond-mat.mes-hall cond-mat.str-el