Dynamical Multiferroicity

An appealing mechanism for inducing multiferroicity in complex oxides is the generation of electric polarization by a spatially varying magnetization that is coupled to the lattice through the spin-orbit interaction. Here, I will describe the reciprocal effect, in which a time-dependent electric polarization induces a magnetization, even in a material composed only of non-magnetic ions [1]. Two predicted consequences of dynamical multiferroicity will be illustrated using the example of strontium titanate as a model material: A Phonon Zeeman Effect, in which previously degenerate optical phonons split in the presence of a magnetic field, and a Quantum Critical Multiferroicity, manifesting as an anomalous magnetic susceptibility in the vicinity of the ferroelectric quantum critical point [2]. Finally, I will discuss possibilities for engineering and optimizing the behaviors using heteroepitaxial strain.

[1] Dynamical multiferroicity, D. M. Juraschek, M. Fechner, A. V. Balatsky and N. A. Spaldin, Phys. Rev. Materials 1, 014401 (2017)
[2] Dynamic multiferroicity of a ferroelectric quantum critical point, K. Dunnett, J.-X. Zhu, N. A. Spaldin, V. Juricic, and A. V. Balatsky, arXiv:1808.05509