Radial Spin Texture of the Weyl Fermions in Chiral Tellurium

We discuss the unconventional spin polarization of the Weyl fermions, which we measured by means of spin- and angle-resolved photoelectron spectroscopy. The exotic alignment of the spins around the Weyl points is a consequence of the chiral symmetry and a fundamental ingredient of the magneto-electric effect.

G. Gatti et al., Phys. Rev. Lett. 125, 216402 (2020)

Trigonal tellurium, a small-gap semiconductor with pronounced magneto-electric and magneto-optical responses, is among the simplest realizations of a chiral crystal. We have studied by spin- and angle-resolved photoelectron spectroscopy its unconventional electronic structure and unique spin texture. We identify Kramers–Weyl, composite, and accordionlike Weyl fermions, so far only predicted by theory, and show that the spin polarization is parallel to the wave vector along the lines in
k space connecting high-symmetry points. Our results clarify the symmetries that enforce such spin texture in a chiral crystal, thus bringing new insight in the formation of a spin vectorial field more complex than the previously proposed hedgehog configuration. Our findings thus pave the way to a classification scheme for these exotic spin textures and their search in chiral crystals.

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G. Gatti et al., Phys. Rev. Lett. 125, 216402 (2020)
DOI: 10.1103/PhysRevLett.125.216402
Ultima modifica il Giovedì, 24 Febbraio 2022 17:23