New tool detects interaction between light and magnetic fields

The perturbation theory provides a powerful tool to describe how molecular systems respond to electromagnetic fields. However, it fails to sufficiently describe how solid matter reacts. Investigation is especially important for magneto-optic materials, where a magnetic field can cause polarised light to rotate as light travels through the material.

At present, there is no theory that sufficiently describes the macroscopic electromagnetic response of solids. What has only been widely studied in recent years is the response to static fields. Scientists within RESPSPATDISP (First-principles theory of spatial dispersion in electromagnetic response of solids: applications to natural optical activity and magnetoelectric effect) worked on extending recent theories to include electromagnetic perturbations that show time dependence.

Through using various approaches, scientists successfully derived an expression for the magneto-optic response of periodic systems to arbitrary electromagnetic fields.

This mathematical formalism was implemented in a scientific open-source programme called Octopus. The developed code can describe the time-dependent electron-ion dynamics of finite and extended systems to arbitrary intense and time-dependent electromagnetic perturbations. Using this code, scientists investigated the magneto-optic response of widely-used semiconductors.

The newly developed versatile tool for spectroscopic analysis can be used intensively for guiding and interpreting new experiments, including those at large facilities such as synchrotron. For future scientific projects, the methodology that the RESPSPATDISP team adopted requires access to top-level supercomputing centres.

The potential discovery of new magneto-optic phenomena in certain carbon nanostructures and topological insulators will expedite advancements in quantum computing and next-generation spintronics devices.