Researchers have made a groundbreaking discovery in the field of quantum materials science, revealing a new way to detect magnons—spinning quasiparticles found in all magnets. Led by Columbia researcher Xiaoyang Zhu, the team demonstrated that magnons in chromium sulfide bromide (CrSBr) can pair with light-emitting excitons, making these elusive particles visible through simple optical effects for the first time.
CrSBr, a magnetic semiconductor that can be reduced to atom-thin 2D layers, has proven to be the ideal material for this breakthrough. When researchers perturbed the magnons with light, they observed oscillations from excitons in the near-infrared range, almost visible to the naked eye. This represents a form of quantum transduction—converting one “quanta” of energy to another.
The significance of this discovery lies in its potential applications. Since excitons have energy four orders of magnitude larger than magnons, their strong pairing enables scientists to easily observe tiny changes in magnons. This could revolutionize quantum information networks by converting information from spin-based quantum bits to light, allowing data transmission over hundreds of miles via optical fibers.
The team noted remarkable coherence time in their experiments, with oscillations lasting beyond the five-nanosecond experimental limit. The phenomenon traveled over seven micrometers and persisted even in devices made of just two atom-thin layers, suggesting possibilities for nano-scale spintronic devices.
Unlike conventional electronics where electrons encounter resistance as they move, spin waves involve no particle movement, potentially leading to more efficient alternatives to today’s electronics. Magnons can also serve as “quantum interconnects” that bind quantum bits together into powerful computers.
This research was supported by Columbia’s NSF-funded Materials Research Science and Engineering Center and a DOE-funded Energy Frontier Research Center. Moving forward, the team plans to explore CrSBr’s quantum information potential and investigate other material candidates that could emit light in a wider range of colors.
“We’re assembling the toolbox to construct new devices with customizable properties,” Zhu concluded, pointing toward a future where quantum materials could transform computing and information transmission.
Reference: Youn Jue Bae, Jue Wang, Allen Scheie, Junwen Xu, Daniel G. Chica, Geoffrey M. Diederich, John Cenker, Michael E. Ziebel, Yusong Bai, Haowen Ren, Cory R. Dean, Milan Delor, Xiaodong Xu, Xavier Roy, Andrew D. Kent, Xiaoyang Zhu. Exciton-coupled coherent magnons in a 2D semiconductor. Nature, 2022; 609 (7926): 282 DOI: 10.1038/s41586-022-05024-1
