Researchers at the City College of New York have identified how light and magnetism interact within atomically thin materials, potentially enabling new quantum technologies. This work explores how “excitons” can influence magnetic states, while separate research in Science has captured the first images of atomic thermal vibrations.
Integrating Light and Magnetism in Layered Semiconductors
Physicists at the City College of New York are investigating a new frontier in quantum science: materials only a few atoms thick where light, charge, and magnetism are intrinsically linked. This research, led by the Laboratory for Nano and Micro Photonics, focuses on van der Waals magnetic semiconductors, such as chromium triiodide and nickel phosphorus trisulfide.
In these systems, light-generated particles known as excitons—formed when light excites an electron and leaves behind a positively charged “hole”—do not merely exist on the surface of the magnetic structure. Instead, they interact directly with the material’s magnetic order and collective waves called magnons.
“In these materials, light and magnetism no longer operate as separate channels. An exciton is not just a passive light-driven excitation sitting on top of the magnetism. It can sense the spin order and magnons, and under the right conditions, even help control the magnetic state itself.”
Pratap Chandra Adak, postdoctoral researcher at the City College of New York
According to the review published in Nature Materials, this shared origin within electronic orbitals allows for advanced control of magnetic states using light. This could lead to developments in magneto-photonic memory, all-optical logic, and quantum transducers that bridge the gap between microwave and optical frequencies.
Imaging Atomic Motion with Electron Ptychography
While researchers at the City College of New York examine the coupling of light and magnetism, a team at the University of Maryland has achieved a distinct breakthrough in visualizing the physical behavior of these thin structures. As reported in Science on July 24, 2025, Yichao Zhang and her colleagues successfully captured the first microscopy images of thermal vibrations in individual atoms.
The team utilized a technique called “electron ptychography,” which reached a resolution better than 15 picometers. This imaging revealed a phenomenon known as “moiré phasons”—patterns created when two-dimensional material layers are twisted. These vibrations are critical because they dictate how heat and electricity propagate through ultra-thin electronics.
“This is like decoding a hidden language of atomic motion. Electron ptychography lets us see these subtle vibrations directly. Now we have a powerful new method to explore previously hidden physics, which will accelerate discoveries in two-dimensional quantum materials.”
Yichao Zhang, assistant professor at the University of Maryland
The Evolution of Atomic-Scale Material Engineering
The ability to manipulate materials at the atomic level has been a long-term goal in physics, tracing back to Richard Feynman’s 1959 lecture. Over the decades, techniques such as molecular beam epitaxy (MBE) allowed scientists to stack semiconductor layers to create heterostructures, which now power modern technologies ranging from LEDs and lasers to solar cells. However, traditional heterostructures face limitations due to atomic spacing mismatches and “dangling” bonds at crystal edges.
The emergence of two-dimensional crystals, such as graphene, provides a solution to these structural constraints. Because these sheets are held together by Van der Waals forces, they lack the dangling bonds that cause defects in thicker crystals. Current research aims to move beyond simple detection of these properties toward active control.
Vinod M.
“Over the past few years, this field has moved from detecting magnetism in atomically thin crystals to actively exploring how magnetic order can control light-matter interactions,” said Menon, professor of physics and senior author of the Review. “The goal of this article is to bring those developments into a coherent framework and identify where the field can go next.”
Vinod M. Menon, professor of physics
Despite these advancements, significant hurdles remain. Theoretical models capable of predicting the simultaneous behavior of excitons, spins, and lattice vibrations in these complex systems are still under development. Future investigations are expected to explore moiré magnetic excitons and the optical control of spin textures, which could define the next generation of energy-efficient and quantum-ready hardware.
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