In standard electrodynamics courses, we learn how electric fields induce polarization or a magnetic field generates magnetization. However, the simultaneous lack of spatial inversion and time-reversal symmetries allow cross-coupling and the magnetoelectric effect emerges. The electric field control of the magnetization in non-centrosymmetric magnets is an interesting question for fundamental science, which may also find applications in new types of sensors, memory and logic devices. As a finite frequency analogue of the magnetoelectric coupling, the electric and magnetic dipole excitations can be mixed in these compounds, which leads to intriguing optical phenomena such as nonreciprocal polarization rotation or light absorption. Moreover, the optical magnetoelectric effect may also open new pathways to control the magnetic order by light.

The PhD candidate will study the coupled spin and polarization dynamics by linear and non-linear spectroscopy in magnetoelectric compounds such as Co3O4 and Co2Mo3O8. (S)he will perform THz and optical spectroscopy at low temperatures and in magnetic and electric fields to characterize the resonance frequencies and the selection rules of the excitations. Beyond the linear regime, (s)he will carry out pump-probe experiments to study the non-trivial spin and polarization dynamics in magnetoelectrics. Part of the research will be carried out in short research visits at collaborating European institutes.