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arXiv · 2210.08221

Parallel spin-momentum locking in a chiral topological semimetal

Jonas A. Krieger·Samuel Stolz·Inigo Robredo·Kaustuv Manna·Emily C. McFarlane·Mihir Date·Eduardo B. Guedes·J. Hugo Dil·Chandra Shekhar·Horst Borrmann·Qun Yang·Mao Lin·Vladimir N. Strocov·Marco Caputo·Banabir Pal·Matthew D. Watson·Timur K. Kim·Cephise Cacho·Federico Mazzola·Jun Fujii·Ivana Vobornik·Stuart S. P. Parkin·Barry Bradlyn·Claudia Felser·Maia G. Vergniory·Niels B. M. Schröter
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Abstract

Spin-momentum locking in solids describes a directional relationship between the electron's spin angular momentum and its linear momentum over the entire Fermi surface. While orthogonal spin-momentum locking, such as Rashba spin-orbit coupling, has been studied for decades and inspired a vast number of applications, its natural counterpart, the purely parallel spin-momentum locking, has remained elusive in experiments. Recently, chiral topological semimetals that host single- and multifold band crossings have been predicted to realize such parallel locking. Here, we use spin- and angle-resolved photoelectron spectroscopy to probe spin-momentum locking of a multifold fermion in the chiral topological semimetal PtGa via the spin-texture of its topological Fermi-arc surface states. We find that the electron spin of the Fermi-arcs points orthogonal to their Fermi surface contour for momenta close to the projection of the bulk multifold fermion, which is consistent with parallel spin-momentum locking of the latter. We anticipate that our discovery of parallel spin-momentum locking of multifold fermions will lead to the integration of chiral topological semimetals in novel spintronic devices, and the search for spin-dependent superconducting and magnetic instabilities in these materials.

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Jonas A. Krieger, Samuel Stolz, Inigo Robredo, Kaustuv Manna, Emily C. McFarlane, Mihir Date, Eduardo B. Guedes, J. Hugo Dil, Chandra Shekhar, Horst Borrmann, Qun Yang, Mao Lin, Vladimir N. Strocov, Marco Caputo, Banabir Pal, Matthew D. Watson, Timur K. Kim, Cephise Cacho, Federico Mazzola, Jun Fujii, Ivana Vobornik, Stuart S. P. Parkin, Barry Bradlyn, Claudia Felser, Maia G. Vergniory, Niels B. M. Schröter. 2022-10-15. Parallel spin-momentum locking in a chiral topological semimetal. https://doi.org/10.1038/s41467-024-47976-0

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