Doped Two-Dimensional Layered Magnets

Luminescent materials with strongly coupled optical and magnetic properties offer unique fundamental probes of electron correlations as well as new opportunities to manipulate and measure spin effects using light. This talk will describe development of a new family of luminescent materials based on doping two-dimensional layered magnets with optical impurities. In one example, we have demonstrated that doping the layered van der Waals ferromagnet CrI₃ with Yb³⁺ transforms this material's nondescript broadband emission into narrow line emission. The improved resolution allows detection of spin correlations, exchange fields, and spontaneous magnetic ordering via luminescence. Strong magnetic exchange coupling between the lattice and the impurity also strongly amplifies the effect of an external field felt by Yb³⁺, again probed by luminescence. Broadening this family of materials has allowed detection of impurity-magnet exchange splittings and their dependence on temperature, external field, and hydrostatic pressure, and has allowed quantitative descriptions of exciton diffusion dynamics. Fundamental aspects of the electronic structures of these materials will be discussed in this context.