Oral: Symmetry induced novel spin textures in non-centrosymmetric systems

In non-centrosymmetric systems, the gradient of the electrostatic potential generates a momentum-dependent magnetic field in the rest frame of the electron. This field locks the electron's spin to its momentum, lifting spin degeneracy of the bands and creating complex spin textures in reciprocal space, primarily enforced by symmetries. Depending on the symmetry, the system may exhibit Rashba, Dresselhaus, Weyl (radial), persistent, or other complex spin textures. Using first-principles electronic structure calculations based on density functional theory (DFT) and supplemented with k.p low-energy model Hamiltonian, we have identified diverse spin textures in nonpolar half-Heusler alloys and nonpolar chiral systems. Our analysis highlights the key role of little group symmetries at specific k-points and the orbital character of the associated bands in defining the spin textures. We observe linear Dresselhaus effect, Rashba effect with both linear and nonlinear terms, as well as nontrivial Zeeman spin splitting and vanishing spin polarization in nonpolar half-Heusler alloys. We show in nonpolar chiral systems, bands with specific orbital characters near a high symmetry point with a D₂ little group may give rise to a single spin-dependent term in the low-energy k·p Hamiltonian, resulting in a persistent spin texture. These diverse spin textures offer promising opportunities for spintronic and spin-valleytronic applications.