Light and magnetism entangled in materials one atom thick

A review maps atomically thin magnetic materials where light and magnetism talk to each other, pointing toward low-power quantum devices.

Researchers at the City College of New York have published a review in Nature Materials surveying a class of atomically thin materials — van der Waals magnetic semiconductors — in which light, electric charge, and magnetism are physically interconnected. Lead author Pratap Chandra Adak and senior author Vinod Menon, working in Menon's photonics lab, pull together where the field stands and what remains open.

The mechanism turns on two objects. An exciton forms when light lifts an electron and leaves behind a positive hole, the pair staying bound as a neutral particle. A magnon is a collective wave rippling through a material's magnetic order. In these thin materials, excitons and magnetic moments can spring from the same electronic orbitals, so light and magnetism can influence each other — coupling optical signals to magnetic activity at gigahertz frequencies. The review examines chromium triiodide, nickel phosphorus trisulfide, and chromium sulfur bromide as platforms.

Why it matters for shared knowledge infrastructure: if optical and magnetic signals can be linked directly in a material, devices like magneto-photonic memory, all-optical logic, and quantum transducers become possible with less energy overhead. Cheaper, lower-power information hardware is foundational to everything built on top of it.

The caveats are central. This is a review summarizing progress, not new experimental results. The authors say much of the field is unexplored and better theory is still needed, and every application listed is a future possibility rather than a demonstrated device. The work was funded by DARPA and the Moore Foundation. What to watch is whether these couplings survive in real, manufacturable devices.

Source: ScienceDaily