Figure 2: Spin polarization for the bands along the M-Γ-M direction.

(a) ARPES data measured at different emission angles. The inset shows the position of this cut in the Brillouin zone and the dot marks the position for energy distribution curves (EDCs) shown in b–d. The red dots and blue crosses stand for the spin directions. (b–d) Spin-resolved EDCs of three spin components (in-plane radial, tangential directions and out-of-plane direction) at emission angle of 7.5° (along the dashed line in a). The EDCs have been corrected by Shirley background (broken lines). Lower panels are extracted spin polarizations. The error bars indicate the statistical fluctuation in determining the spin polarizations (proportional to where N is the photoemission intensity). (e) EDCs of spin-up and spin-down states at different emission angles. (f) Spin polarization at different emission angles. Red indicates spin-up states and blue indicates spin-down states along tangential direction.