Reviewed by Lexie CornerMar 13 2025
Researchers at the Cavendish Laboratory, in collaboration with the European High Magnetic Field Lab in Nijmegen, the University of Warwick, University College London, and Freie Universität Berlin, examined the potential of phosphorene nanoribbons for magnetic and semiconducting properties.
A schematic of the photoexcited dipole dynamics in phosphorene nanoribbons, where following photoexcitation the excited state relaxes to the ribbon edge. Here, the excitation is coupled to a symmetry forbidden edge phonon mode and is where the magnetism is likely present. Image Credit: Arjun Ashoka, Junior Research Fellow at Trinity College, University of Cambridge, and Raj Pandya, who was a Junior Research Fellow at the Cavendish Laboratory at the time of this research and is now at the University of Warwick.
Phosphorene nanoribbons (PNRs), which are only a few nanometers wide, are strips of black phosphorus that have long been thought to possess unique magnetic and semiconducting properties. However, confirming these properties has been challenging.
The researchers explored the magnetic and semiconducting potential of these nanoribbons.
Using techniques such as electron paramagnetic resonance and ultrafast magneto-optical spectroscopy, they demonstrated the magnetic behavior of PNRs at room temperature and how these magnetic properties interact with light.
At ambient temperature, the nanoribbons displayed macroscopic magnetic characteristics. Iron filings align in solution under relatively small magnetic fields (<1T), similar to their behavior around traditional magnets.
Furthermore, these macroscopic magnetic properties were observed only when the nanoribbons were in thin sheet form, comparable to the behavior of metals like iron and nickel.
Most excitingly, we discovered that in addition to these magnetic properties, PNRs host excited states on the magnetic edge of the nanoribbon, where it interacts with atomic vibrations (phonons) that are normally not allowed by the material’s bulk symmetries. This unusual interaction allows PNRs to uniquely couple magnetic, optical, and vibrational properties on its one-dimensional edge.
Arjun Ashoka, Junior Research Fellow and Study First Author, Trinity College
“For years, we've explored and utilized the devilish yet benevolent 2D surfaces of 3D materials, from catalysis to device physics. With these new nanoribbons, we've hopefully unlocked access to new physics on the 1-dimensional analog of a 2D surface: an edge,” continued Ashoka.
This work is particularly noteworthy as it provides the first experimental confirmation of the anticipated, yet challenging-to-observe, magnetic characteristics of phosphorene nanoribbons.
The confirmation that phosphorene nanoribbons are intrinsically both semiconducting and magnetic—without requiring low temperatures or doping—is particularly important and novel. While this property was predicted, directly observing it is an incredible validation of those predictions.
Chris Howard, University College London
Howard’s team was the first to synthesize these nanoribbons.
The most significant aspect of this research is its potential impact on various scientific and technological fields. The study could lead to the development of spintronic devices, which use electron spin instead of charge, enabling advancements in computing technologies such as next-generation transistors, flexible electronics, and scalable fabrication for quantum devices.
The best thing about this work, apart from being a really exciting finding, has been the great team we have worked with over 10 institutes and 5 years, highlighting the amazing science that can be done when we work together.
Raj Pandya, Corresponding Author, University of Warwick
Raj Pandya was a Junior Research Fellow at the Cavendish Laboratory during this research.
The researchers are focused on the future of their work. Their next steps involve investigating how magnetism interacts with light and vibrations at the edges of these ribbons and exploring their potential to create new types of devices.
Journal Reference:
Ashoka, A., et al. (2025) Magnetically and optically active edges in phosphorene nanoribbons. Nature. doi.org/10.1038/s41586-024-08563-x