Topological magnetism of SrRuO₃ driven and controlled by ferroelectric interface

Ferroelectric–ferromagnetic interfaces in complex oxides offer a platform for emergent magnetoelectric and topological phenomena. Using density functional theory combined with a Green’s function approach and atomistic spin-model simulations, we explore how the polarization of BaTiO₃ influences the magnetic texture in SrRuO₃(001) films. Ferroelectric proximity induces Ru off-centering within rotated RuO₆ octahedra, modulating local crystal fields and Ru magnetic moments. The polarization direction controls exchange interactions; when pointing toward SrRuO₃, collinear ferromagnetism is favored, while polarization reversal introduces frustration that stabilizes noncollinear and antiferromagnetic states. The out-of-plane Dzyaloshinskii–Moriya interaction exceeds local anisotropy, forcing in-plane canting and enabling chiral spin textures. Under these conditions, merons and bimerons emerge spontaneously within the interfacial and adjacent SrRuO₃ layers, tunable by magnetic field. These topological quasiparticles may be responsible for the topological Hall effect, which has been previously observed experimentally [1]. These findings demonstrate polarization-controlled topological magnetism at BaTiO₃/SrRuO₃ interfaces, offering new routes for nanoscale magnetoelectric spintronic control.

[1] L. Wang et al., Nat. Mater. 17, 1087 (2018)