Data storage, sensing, and waveguiding are just a few of the applications for materials whose response to light changes in a magnetic field. The root of this magneto-optical (MO) effect is usually the material’s own magnetism. Researchers have now found that a surprisingly large MO effect can arise from electrons becoming self-trapped by their distortion of the surrounding crystalline lattice. The concentration of such polaron states in a material can be tuned by strain, so the finding might suggest a route to mechanical or electromechanical control of the MO effect.

This research is published in Physical Review Letters.