Sensing multiferroic states non-invasively using optical second harmonic generation

The current boost in the search for energy-efficient device paradigms motivates the integration of materials with coexisting and coupled electric and magnetic order parameters into application-relevant architectures. In the so-called multiferroic magnetoelectrics, the understanding of switching events, however, is most of the time obstructed by the complex physics involved and in the non-trivial domain and domain walls configurations. This perspective offers an insightful overview of the most recent progress in non-invasive, optical probe of technology-significant ferroelectricity and antiferromagnetic order: the optical second harmonic generation (SHG). Over the last decade its use in material science has evolved and SHG is now enabling the monitoring of the emergence of polarization in thin films, even during the epitaxial deposition process. Its long working distance further expedites the probe of multiple order parameters in various environment and under multi-stimuli excitations. The potential for the probe of complex electric dipole textures such as ferroelectric skyrmions and time-resolved measurements using SHG-based approach in most recent materials systems will be discussed.