Bold claim first: ultrathin materials reveal a clockwork of magnetism that could redefine nanoscale tech. Now the details, rewritten for clarity and reach.
Physicists have taken a single-atom-thick material and uncovered a sequence of unusual magnetic phases as it cools. In Nature Materials, a UT Austin team reports experimental evidence that this ultrathin layer realizes, for the first time, a two-dimensional (2D) magnetic model first proposed in the 1970s. Their work suggests new possibilities for extremely small, energy-efficient devices.
The study focuses on an atomically thin sheet of nickel phosphorus trisulfide (NiPS3). As the temperature is lowered from about –150°C to –130°C, the material enters a Berezinskii–Kosterlitz–Thouless (BKT) phase. In this regime, the magnetic moments of atoms form swirling configurations known as vortices. Pairs of these vortices wind in opposite directions—one clockwise, the other counterclockwise—and stay bound together. This BKT phase is notable because the vortices are predicted to be unusually robust and confined to just a few nanometers laterally, within a single atomic layer of thickness.
The researchers emphasize that the BKT phase is a striking demonstration of topological physics in a truly two-dimensional magnet, offering a new way to steer magnetism at the nanoscale and to explore universal notions of topology in 2D systems.
As cooling continues, the same NiPS3 sheet transitions into a second magnetic phase: a six-state clock ordered phase. In this state, the magnetic moments settle into one of six symmetry-related directions. Observing both the BKT phase and this low-temperature ordered state in the same system provides experimental realization of the long-theorized two-dimensional six-state clock model, a canonical framework from the 1970s.
The team’s lead, Edoardo Baldini, describes the result as a complete demonstration of the full phase sequence that the 2D six-state clock model predicts—and as evidence that nanoscale magnetic vortices can emerge naturally in a purely two-dimensional magnet.
Looking ahead, the researchers aim to stabilize similar magnetic phases at higher temperatures, ideally approaching room temperature, by tuning material properties. This initial observation lays a crucial foundation for that effort.
Beyond NiPS3, the findings hint that a broad class of two-dimensional magnetic materials might host previously hidden phases, opening new directions for fundamental physics and for nanoscale device concepts.
Funding came mostly from the National Science Foundation (NSF), including UT’s Center for Dynamics and Control of Materials and the NSF Materials Research Science and Engineering Center. Additional support for the Baldini group came from Love, Tito’s; the Robert A. Welch Foundation; the W. M. Keck Foundation; an NSF CAREER award; the U.S. Air Force Office of Scientific Research Young Investigator Program; and the U.S. Army Research Office.
The three senior authors—Baldini, Allan MacDonald, and Xiaoqin “Elaine” Li—are UT physicists and members of the Texas Quantum Institute, with Li co-directing the institute. Co-first authors include Frank Y. Gao and Dong Seob Kim, both UT researchers moving on to new positions elsewhere. Collaborators from MIT, Academia Sinica, and the University of Utah contributed to the work.
If you’re curious about what this means for technology: think of ultra-compact memory and logic components that operate with minimal energy loss, powered by the exotic behaviors of electrons in two dimensions. And this is the part most people miss: stabilizing these phases at higher temperatures isn’t just a technical hurdle—it would unlock practical, room-temperature devices that harness topological magnetism for robust operation.
What do you think about pursuing room-temperature 2D magnetic phases? Could these findings spark a new era of nanoscale technologies, or do you foresee significant material science challenges ahead? Share your thoughts in the comments.
