An international research team led by Dr. Rostislav Mikhaylovskiy of Lancaster University has reported new insights into how magnetic materials respond to ultrafast light excitation. The work focuses on how extremely short electromagnetic pulses, lasting less than a trillionth of a second, can be used to steer magnetic spin states with an efficiency that exceeds previous expectations. The study adds to a growing body of research aimed at understanding and controlling magnetism on timescales far beyond those accessible with conventional electronic methods.
Leenders, R. A., Kovalenko, O. Y., Saito, Y., Vovk, N. R., Kimel, A. V., & Mikhaylovskiy, R. V. (2025). THz-Driven Spin Dynamics in Orthoferrites with Kramers and Non-Kramers Rare-Earth Ions. Physical Review Letters, 135(24), 246703. https://doi.org/10.1103/ldnx-67qz
Magnetic materials remain central to modern engineering, particularly in data storage and emerging spin based technologies. In most practical systems, magnetization is controlled using electric currents or static magnetic fields, approaches that are limited by speed and energy dissipation. Ultrafast optical excitation offers an alternative pathway, enabling researchers to interact with magnetic order on femtosecond and picosecond timescales. This capability is of particular interest for applications where switching speed and energy efficiency are critical design constraints.
Dr. Rostislav Mikhaylovskiy of Lancaster University stated,
“We believe that this exciting discovery will stimulate further studies of the mechanisms governing the efficient and rapid control of magnetization for future quantum technologies.”
In the Lancaster led experiments, researchers applied ultrashort electromagnetic pulses to carefully chosen magnetic materials and then measured how the direction of magnetization changed in response. Two closely related materials were studied, differing mainly in the electronic orbitals associated with their rare earth elements. Despite their structural similarity, the materials responded very differently to the light pulses. One showed a spin deflection that was roughly ten times larger than the other, a difference traced back to stronger coupling between electron orbital motion and spin.
At the atomic level, magnetism arises from the behavior of electrons, which possess both orbital motion around the nucleus and an intrinsic angular momentum known as spin. These spins act like tiny magnetic moments, and their collective alignment determines the magnetization of a material. In many systems, orbital motion is treated as a secondary effect. The new findings show that when orbital and spin dynamics are strongly linked, the response of the magnetization to external stimuli such as light can be significantly enhanced.
The experiments suggest that ultrafast light pulses can perturb electron orbitals, which then transfer angular momentum to the spins through spin orbit interactions. This indirect route allows magnetization to be steered without relying on heating or large electrical currents. From an engineering perspective, this mechanism points toward material design strategies in which orbital characteristics are deliberately tuned to improve magnetic controllability.
Similar ultrafast magnetic phenomena have been explored in other laboratories using femtosecond infrared pulses and terahertz radiation to probe spin dynamics and generate spin polarized currents. Together, these studies show that magnetic systems can respond coherently on extremely short timescales, opening opportunities for devices that operate far faster than today’s memory and logic components.
While the current work is fundamental in nature, it has implications for future technologies such as ultrafast magnetic memory, spintronic logic, and quantum devices that rely on precise control of spin states. Achieving practical implementations will require advances in materials engineering, compact ultrafast light sources, and device integration. Nevertheless, understanding how orbital and spin dynamics combine to amplify magnetic responses provides a valuable framework for engineers working at the intersection of photonics, magnetism, and advanced materials.
Adrian graduated with a Masters Degree (1st Class Honours) in Chemical Engineering from Chester University along with Harris. His master’s research aimed to develop a standardadised clean water oxygenation transfer procedure to test bubble diffusers that are currently used in the wastewater industry commercial market. He has also undergone placments in both US and China primarely focused within the R&D department and is an associate member of the Institute of Chemical Engineers (IChemE).
