Multimodal Topological Textures Arising from Coupled Structural Orders in SrTiO₃

Magnetic spin topological textures have recently found electrical counterparts in polar topologies arising from inhomogeneous polar distortions. Here, we extend this concept to nonpolar structural degrees of freedom. Using SrTiO₃ as a prototype, we rely on second-principles atomistic simulations to investigate equilibrium domain structures and topological textures associated with its natural antiferrodistortive oxygen-octahedra rotations. Beyond the common 90° antiferrodistortive domain walls, we identify under compressive epitaxial strain metastable 180° walls oriented along {100}_pc. These domains exhibit complex Bloch- and Néel-like antiferrodistortive configurations, with the Néel type being energetically preferred. We also stabilize antiferrodistortive vortex and antivortex structures that colocalize with polarization vortices and a modulated local strain field, producing trimodal topological textures. Our results extend topological-ordering concepts to nonpolar structural modes and open the door to the cross-control of distinct textures.