Light and Magnetism Finally Speak the Same Language in Atomically Thin Materials

For decades, physicists have treated light and magnetism as separate domains in the quantum world. A comprehensive review published in Nature Materials by researchers at the City College of New York and their international collaborators now shows that in atomically thin materials, the two are inseparably linked — and the implications could transform how we build quantum computers, sensors, and memory devices.

The key lies in a class of materials called van der Waals magnetic semiconductors, which can be peeled down to single-atom thickness. When light strikes these materials, it creates particle-like excitations called excitons. Meanwhile, the material's magnetic order produces collective spin waves known as magnons. The review reveals that excitons and magnons in these 2D materials interact far more strongly than previously thought, forming hybrid quasiparticles that combine optical and magnetic properties.

"In these materials, light and magnetism no longer operate as separate channels," said Pratap Chandra Adak, a postdoctoral researcher and lead author of the review. The team identified three key phenomena: excitons can directly control magnetic behavior through magneto-optical effects; magnons can modulate how excitons absorb and emit light; and the two can bind together into exciton-magnon complexes that behave like tiny, magnetically tunable light switches.

This coupling is uniquely accessible in 2D materials because their reduced dimensionality amplifies quantum interactions. The review maps a roadmap for building quantum transducers — devices that convert between optical signals (photons) and magnetic signals (magnons) without losing quantum information. Such transducers are a critical missing piece for connecting quantum computers to fiber-optic networks.

Unlike many quantum platforms that require near-absolute-zero temperatures, some of these 2D magnetic semiconductors operate at higher temperatures, potentially enabling practical quantum devices that do not rely on expensive cryogenic cooling. The review also highlights opportunities for room-temperature magneto-optical modulators and ultra-compact magnetic field sensors.