Light-matter interaction is a long-standing promising topic that can be dated back to a few centuries ago and has witnessed the long-term debate between the particle and wave nature of light. In modern condensed matter physics and materials science, light usually serves as a detection tool to effectively characterize the physical and chemical features of samples. The light modulation on intrinsic properties of materials, such as atomic geometries, electronic bands, and magnetic behaviors, is more intriguing for information control and storage. This corresponds to a light-induced order parameter switch in the phase space. Most prior works focus on the situation when photon energy is larger than the material band gap, in which the photon is absorbed by the electron subsystem and then transfers its energy into other subsystems such as phonon and spin. This can be described by the imaginary part of the dielectric function. In contrast, recent theoretical predictions and experimental advances have suggested that the real part of dielectric function could also vary the energy landscape in phase space, so that it triggers phase transition in an athermic approach (without direct photon absorption). In this Perspective, we review some recent theoretical, computational, and experimental developments of such a low-frequency light-induced phase transition, focusing on ferroic and topological order parameters. We also elucidate its fundamental mechanisms by comparing it with the optical tweezers technique, and light irradiation could trigger impulsive stimulated Raman phonon excitation. Finally, we propose some further developments and challenges in such a nonresonant light-matter interaction.

Link:Nonvolatile Ferroic and Topological Phase Control under Nonresonant Light - PubMed