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, stemming from low symmetry that is responsible for its exotic transport properties [1]. 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 of the initial state in the photoemission process, and as such it cannot be eliminated, but only its magnitude influenced, by special experimental geometries.

[1] T. Heider, G. Bihlmayer, J. Schusser, F. Reinert, J. Minár, S. Blügel, C. M. Schneider, and L Plucinski, Geometry-induced spin-filtering in photoemission maps from WTe2 surface states, arXiv.2210.10870 (2022), https://doi.org/10.48550/arXiv.2210.10870.