Persistent spin texture as a universal property of bulk crystals

Crystal symmetries shape several fundamental properties of materials. Among them is the spin polarization of bands across the reciprocal space, which influences charge-to-spin conversion and spin dynamics. Persistent spin texture (PST) represents a uniform spin polarization in certain regions of the Brillouin zone, where it remains independent of momentum. This property supports persistent spin helix states with extended spin lifetimes, enhancing spin coherence. However, PSTs have been hardly explored experimentally, as they were believed to be rare and limited to quantum wells and a few solids. Here, we use group theory to establish general conditions for symmetry-protected PSTs in bulk crystals, revealing that they are universally present in all nonmagnetic solids lacking inversion symmetry. When the Fermi surface coincides with a PST region, the material can sustain persistent spin helix states protected by crystal symmetry. Contrary to previous works focused on specific material classes, we use irreducible representations of double grey groups to provide a general classification of PST across all crystal symmetries. Our findings, supported by first-principles simulations of a few promising materials, open a new route for the design of spintronics materials.