2016/03/16 by L. Bawden, S. P. Cooil, F. Mazzola +13 · 1 citation
Physics and Astronomy · #cond-mat.supr-con #cond-mat.mes-hall #cond-mat.mtrl-sci #cond-mat.str-el
paper · pdf · doi:10.1038/ncomms11711
published as Nature Communications 7, 11711 (2016) · 7 pages, 4 figures
arxiv created 2016/03/16 · arxiv updated 2016/05/26
The metallic transition-metal dichalcogenides (TMDCs) are benchmark systems for studying and controlling intertwined electronic orders in solids, with superconductivity developing upon cooling from a charge density wave state. The interplay between such phases is thought to play a critical role in the unconventional superconductivity of cuprates, Fe-based, and heavy-fermion systems, yet even for the more moderately-correlated TMDCs, their nature and origins have proved highly controversial. Here, we study a prototypical example, 2H-NbSe2, by spin- and angle-resolved photoemission and first-principles theory. We find that the normal state, from which its hallmark collective phases emerge, is characterised by quasiparticles whose spin is locked to their valley pseudospin. This results from a combination of strong spin-orbit interactions and local inversion symmetry breaking. Non-negligible interlayer coupling further drives a rich three-dimensional momentum-dependence of the underlying Fermi surface spin texture. Together, these findings necessitate a fundamental re-investigation of the nature of charge order and superconducting pairing in NbSe2 and related TMDCs.