Berlin 2018 – scientific programme
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DS: Fachverband Dünne Schichten
DS 1: Layer Properties: Electronic, Optical and Mechanical
DS 1.8: Talk
Monday, March 12, 2018, 11:15–11:30, H 0111
Non-degenerate valleys in transition metal layered WS2 — Omar Messaoudi1,2, •Julen Ibañez-Azpiroz2, and Samir Lounis2 — 1Université Mouloud Mammeri de Tizi Ouzou, Tizi Ouzou, Algeria — 2Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich & JARA, D-52425 Jülich, Germany
We present a comparative first principles investigation of the electronic properties of monolayer WS2 coated with an overlayer of a transition metal (Fe, Co, Mn). Fe outstands as the most prominent candidate where our ab initio calculations reveal that the system is a half-metallic ferromagnet with a gap of 1 eV for the majority spin channel. Furthermore, the combined effect of time-reversal symmetry breaking, due to the magnetic Fe overlayer, and the large spin-orbit coupling induced by W gives rise to non-degenerate K and K* valleys. This has a tremendous impact on the excited state properties induced by externally applied circularly polarized light. Our analysis demonstrates that the latter induces a singular hot spot structure of the transition probability around the K and K* valleys for right and left circular polarization, respectively. We trace back the emergence of this remarkable effect to the strong momentum dependent spin-noncollinearity of the valence band involved. As a main consequence, a strong valley-selective magnetic circular dichroism is obtained, making this system a prime candidate for spintronics and photonics applications.