Review maps how ultrathin magnets could connect light and spin
City College of New York researchers say van der Waals magnetic semiconductors may open routes to optical memory and quantum devices.
By Priya Raghavan · Science Reporter
3 min read
A City College of New York-led team has published a review in Nature Materials on atomically thin magnetic materials in which light-driven particles can interact with magnetic order. The researchers say the field could help build devices that use light, electric charge and electron spin in the same platform.
The review, titled “Excitons in van der Waals magnetic materials,” comes from physicist Vinod M. Menon’s Laboratory for Nano and Micro Photonics at CCNY. According to CCNY, the work pulls together recent findings on layered magnetic semiconductors only a few atoms thick.
The central particles in the review are excitons, which form when incoming light moves an electron and leaves behind a positively charged hole. CCNY said the linked electron-hole pair has no net electric charge, while still coupling strongly to light.
The researchers also focus on magnons, which are waves moving through an ordered magnetic structure. In van der Waals magnetic semiconductors, the review says, excitons and magnetic moments can arise from the same electronic orbitals, giving light and magnetism a direct way to affect each other inside a single crystal.
Pratap Chandra Adak, a postdoctoral researcher in Menon’s group and lead author of the review, said these materials allow excitons to respond to spin order and magnons, and in some cases may help change a magnetic state. CCNY described that as a shift from treating optical activity and magnetism as separate effects.
The review discusses several material systems, including chromium triiodide, nickel phosphorus trisulfide and chromium sulfur bromide. According to the authors, work on these two-dimensional magnets has shown that excitons can enhance magneto-optical effects, making it possible to read magnetic states through changes in light polarization.
The review also says magnetic order can change exciton energies and affect where excitons are confined in a material. Interactions between excitons and magnons may link optical signals to magnetic behavior at gigahertz frequencies, according to the authors.
Menon, a physics professor at CCNY and senior author of the review, said the field has moved in recent years from detecting magnetism in atomically thin crystals toward studying how magnetic order shapes light-matter interactions. He said the review aims to organize those developments and point to open directions for research.
The authors identify possible uses in magneto-photonic memory, optical data readout, all-optical logic, tunable light-emitting devices, magneto-optic lasers and polaritonic technologies. They also point to quantum transducers, devices that convert signals between microwave and optical frequencies, as a possible role in future quantum networks.
CCNY said substantial challenges remain. Many candidate materials have not been studied in depth, and the review says researchers need stronger theoretical models for systems where excitons, electron spins, lattice vibrations and photons interact at the same time.
The paper lists future research directions including moiré magnetic excitons, optical control of spin textures, magneto-photonic devices, magnetic exciton polariton condensation and microwave-to-optical conversion for quantum communication. Co-authors include Florian Dirnberger of the Technical University of Munich, Swagata Acharya of the National Laboratory of the Rockies, Akashdeep Kamra of Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau and Xiaodong Xu of the University of Washington.
CCNY said work at the college was supported by DARPA and the Gordon and Betty Moore Foundation. The journal reference lists the paper under DOI 10.1038/s41563-026-02636-0.
This story draws on original reporting from ScienceDaily.