Geometry-induced spin-filtering in photoemission maps from WTe2 surface states

We demonstrate that an important quantum material WTe₂ exhibits a new type of geometry-induced spin-filtering effect in photoemission [1], stemming from low symmetry that is responsible for its exotic transport properties. Through the laser-driven spin-polarized angle-resolved photoemission Fermi surface mapping, we showcase highly asymmetric spin textures of electrons photoemitted from the surface states of WTe₂. Such asymmetries are not present in the initial state spin textures, which are bound by the time-reversal and crystal lattice mirror plane symmetries. The findings are reproduced qualitatively by theoretical modeling within the one-step model photoemission formalism. The effect could be understood within the free-electron final state model as an interference due to emission from different atomic sites. The observed effect is a manifestation of time-reversal symmetry breaking by the photoemission process. As such, it cannot be eliminated, but only its magnitude influenced, by special experimental geometries.

If time allows we will discuss similar effects in spin-polarized and circular dichroic ARPES maps from PtTe₂, WSe₂, and CrGeTe₃.