Multimodal Topological Textures Arising from Coupled Structural Orders in SrTiO 3

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 100pc. 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.