Radial Spin Texture in Elemental Tellurium with Chiral Crystal Structure

Abstract

The chiral crystal is characterized by a lack of mirror symmetry and an inversion center, resulting in the inequivalent right-and left-handed structures. In the noncentrosymmetric crystal structure, the spin and momentum of electrons are locked in the reciprocal space with the help of the spin-orbit interaction. To reveal the spin textures of chiral crystals, here we investigate the spin and electronic structure in p-type semiconductor elemental tellurium with a chiral crystal structure by using spin-and angle-resolved photoemission spectroscopy. Our data demonstrate that the highest valence band crossing the Fermi level has a spin component parallel to the electron momentum around the BZ corners. Significantly, we have also confirmed that the spin polarization is reversed in the crystal with the opposite chirality. The results indicate that the spin textures of the right-and left-handed chiral crystals are hedgehog-like, leading to unconventional magnetoelectric effects and nonreciprocal phenomena.

Kramers Weyl semimetals as quantum solenoids and their applications in spin-orbit torque devices

“…In those materials within the point group T; O f g, the high symmetry may also enable extra multi-fold point degeneracies to appear at k 0 [15][16][17] . In the materials CsCuBr 3 18 , elemental Te, Se [35][36][37][38] , etc., the dihedral point group there has lower crystal symmetry and allows the anisotropy to show up in the Weyl Hamiltonian…”

“…For KWS with dihedral (D n ) point groups, such as CsCuBr 3 18 , and elemental Te, Se [35][36][37][38] , a pure longitudinal magnetoelectric response can also be obtained when the electric field is applied along the direction of the symmetry axes. On the other hand, for KWS with cyclic (C n ) point groups, such as Ca 2 B 5 Os 3 , a longitudinal magnetoelectric response is generally accompanied with a transverse response.…”

Pressure-induced Anderson-Mott transition in elemental tellurium

“…Due to a strong spin-orbit coupling (SOC), the top of the VB in tellurium has a double maximum and possesses a radial spin texture 7,8 . This is particularly important, since tellurium is naturally doped by vacancies, turning chemically pure samples into a p-type semiconductor exhibiting extrinsic resistivity curves [9][10][11] .…”

Finding Spin Hedgehogs in Chiral Crystals

“…Precisely what directions are open to the electron depend on the material's spin texture-how its spins are arranged in momentum space. Now, for the first time, Masato Sakano, at the University of Tokyo, and colleagues have discovered a spin texture with a hedgehog pattern that prevents an electron from scattering backwards along its path and that also suppresses scattering in all other directions [1]. The effect should greatly influence the resistivity of a material-especially in a magnetic field-and might even be used to generate pure spin currents.…”

“…(In Ref. [1], the team use the spin magnetic moment, which is opposite to the electron spin considered here.) Both the measurement of the purely radial spin texture and its inversion with chirality are the first of their kind and show again the strong coupling between electron spin and crystal symmetry.…”