Nonrelativistic spin splitting (NRSS) in compensated magnetic materials is drawing considerable attention due to its potential impact in next-generation spintronic devices. While NRSS is typically restricted to materials with particular symmetry constraints, here we demonstrate, using density functional theory (DFT) and tight-binding transport calculations, that twin boundaries can induce NRSS in magnetic systems where it is otherwise forbidden. We focus on two representative material systems: the tetragonal perovskite oxide BiCoO3 with 90∘ ferroelastic domain walls, and the rhombohedral layered delafossite-type oxide CoO2, supporting 71∘, 109∘, and 135∘ twin boundaries. Our results reveal that, if these boundaries coexist with ferromagnetic domain walls, they consistently produce NRSS similar to that of d-wave altermagnets, with nodal surfaces dictated by the underlying symmetry of the supercell containing the twin boundary. Tight-binding models further elucidate how the NRSS and derived transport properties scale with domain size and density. Our results put forward twin boundary engineering as a versatile route to realize and control spin splitting in a broader class of materials.
@article{arxiv.2511.14029,
title = {Twin-boundary-induced nonrelativistic spin splitting},
author = {Kristoffer Eggestad and Marc Vila and Sverre M. Selbach and Sinéad M. Griffin},
journal= {arXiv preprint arXiv:2511.14029},
year = {2025}
}