“Topological magnetoelectric effects in two-dimensional magnets”
The study of magnetoelectric effects in solids has drawn extraordinary interest not only from a fundamental perspective, but also from the standpoint of applications. Since efficient control of magnetism with electric probes is highly desirable, materials exhibiting a strong magnetoelectric response properties are at the forefront of quantum materials research. This talk will discuss the prediction of new types of linear magnetoelectric effects in special classes of two-dimensional inversion-breaking antiferromagnets, which manifest as electronic charge polarization induced by in-plane magnetic fields, or an orbital magnetization induced by a perpendicular electric displacement field. In particular the latter effect, i.e., the ability to control and switch magnetization by applying electric fields, suggests promising applications in the very active field of two-dimensional bilayer or few-layer materials.
A key finding this talk will emphasize is that the corresponding the magnetoelectric polarizabilities (i.e., the magnetoelectric response coefficients) include a piece which originates from quantum geometry. This topological contribution is reminiscent of the (quantized) magnetoelectric polarizability of three-dimensional topological insulators, in which case it encodes the strong Z2 topology. In the case of two-dimensional magnets, it can be traced back to the (quasi-)topological electromagnetic response of 2D Dirac semimetals, suggesting a generalization of topological magnetoelectric effects to two dimensions. A connection with materials will be made by calculating the magnetoelectric polarizability in minimal microscopic models motivated by experimentally available material families of current interest.
Host: Daniil Antonenko