In ordinary materials, light, electricity and magnetism mostly behave as separate actors. In a fast-growing branch of quantum science, that separation breaks down. Researchers at the City College of New York are mapping how, in materials only a few atoms thick, these forces intertwine — and why that matters for the next generation of devices.
The work comes from physicist Vinod M. Menon's Laboratory for Nano and Micro Photonics. In a review published in Nature Materials titled "Excitons in van der Waals magnetic materials," the team surveys recent progress in layered magnetic semiconductors — sheets held together by weak van der Waals forces, the same kind of bonding that lets graphite cleave into graphene.
The key players are excitons and magnons. An exciton forms when incoming light energizes an electron and knocks it loose, leaving behind a positively charged "hole"; the pair stays bound and can interact strongly with light despite carrying no net charge. A magnon is different: it is a wave that travels through a material's organized magnetic structure. For years, scientists tried to combine the light-handling talent of exciton-rich semiconductors with magnetism, often by doping in magnetic atoms — an approach that came with trade-offs.
The new class of van der Waals magnetic materials lets excitons and magnons coexist and talk to each other naturally. That union could eventually support optoelectronic devices and quantum technologies that manipulate light, electric charge and electron spin together, rather than shuttling between separate components.
Knowledge takeaway: in atomically thin van der Waals magnetic materials, light-generated excitons and magnetic magnons can coexist and interact in the same sheet; this coupling of light, charge and spin could enable more compact, efficient quantum and optoelectronic devices than today's separately engineered components.