2014/08/28 by J. M. Riley, F. Mazzola, M. Dendzik +14 · 2 citations
Physics and Astronomy · #cond-mat.mtrl-sci #cond-mat.mes-hall
paper · pdf · doi:10.1038/nphys3105
published as Nature Physics 10, 835 (2014) · 6 pages, 4 figures
arxiv created 2014/08/28 · arxiv updated 2022/02/16
Methods to generate spin-polarised electronic states in non-magnetic solids are strongly desired to enable all-electrical manipulation of electron spins for new quantum devices. This is generally accepted to require breaking global structural inversion symmetry. In contrast, here we present direct evidence from spin- and angle-resolved photoemission spectroscopy for a strong spin polarisation of bulk states in the centrosymmetric transition-metal dichalcogenide WSe2. We show how this arises due to a lack of inversion symmetry in constituent structural units of the bulk crystal where the electronic states are localised, leading to enormous spin splittings up to ∼ 0.5 eV, with a spin texture that is strongly modulated in both real and momentum space. As well as providing the first experimental evidence for a recently-predicted `hidden' spin polarisation in inversion-symmetric materials, our study sheds new light on a putative spin-valley coupling in transition-metal dichalcogenides, of key importance for using these compounds in proposed valleytronic devices.