Emergent Surface Multiferroicity

作者：Sayantika Bhowal, Andrea Urru, Sophie F. Weber, Nicola A. Spaldin · 发表于：Physical Review Letters · 年份：2025 · DOI：10.1103/physrevlett.134.146703 · 被引用次数：8 · 研究领域：Multiferroics and related materials、Ferroelectric and Piezoelectric Materials、2D Materials and Applications

We show that the surface of a centrosymmetric, collinear, compensated antiferromagnet, which hosts bulk ferroically ordered magnetic octupoles, exhibits a linear magnetoelectric effect, a net magnetization, and a net electric dipole moment. Thus, the surface satisfies all the conditions of a multiferroic, in striking contrast to the bulk, which is neither polar nor exhibits any net magnetization or linear magnetoelectric response. Of particular interest is the case of nonrelativistic d-wave spin split antiferromagnets, in which the bulk magnetic octupoles and consequently the surface multiferroicity exist even without spin-orbit interaction. We illustrate our findings using first-principles calculations, taking FeF_{2} as an example material. Our Letter underscores the bulk-boundary correspondence in these unconventional antiferromagnets.