- Light can rapidly change magnetic behavior, hinting at faster data storage methods
- Researchers controlled magnets thinner than a hair without cooling or extreme conditions
- Laser pulses change magnet behavior by up to forty percent at room temperature
Modern digital life relies heavily on the efficiency with which information can be stored and processed.
From hard drives to emerging computer systems, magnetism remains at the heart of these technologies because it governs how bits are written, moved and stored.
Engineers have long sought ways to adjust magnetic behavior quickly and precisely without relying on high-heat electrical currents.
Going beyond inconvenient laboratory conditions
Light has often been proposed as an alternative control tool, but most demonstrations have required extreme conditions that limit real-world relevance.
Many previous experiments have shown that laser pulses can influence magnetic excitations, but only in bulk materials, at very low temperatures or via specialized mid-infrared laser systems.
These constraints make integration into everyday hardware difficult, as such conditions conflict with scalable manufacturing and practical operation of devices.
In this context, researchers from Germany, Switzerland and Italy have recently reported experimental results indicating that such limitations may not be inevitable.
Their study, published in Natural communicationsexplores whether magnetic excitations can be optically tuned in ultrathin materials operating at room temperature and under modest magnetic fields.
The study focuses on a nanometer-thick film of bismuth-substituted yttrium iron garnet grown on a crystalline substrate that introduces stress into the film.
This constraint forces the magnetization to orient itself out of the plane, thus creating a well-defined magnetic state before excitation.
Using femtosecond pump probe techniques, the researchers monitored the magnetization response after short pulses of visible light struck the material.
Since the photon energy exceeds the bandgap of the material, laser-induced heating dominates rather than selective resonant excitation.
The team applied an external magnetic field of less than 200 mT to control the starting magnetic configuration.
Under these conditions, the researchers observed that the laser pulses could increase or decrease the frequency of coherent magnons by up to 40%.
Magnons represent collective spin oscillations, and their frequency determines how magnetic information propagates through a material.
The direction of the frequency change depends on both the applied magnetic field and the laser fluence.
Lower fields favored frequency reductions at moderate fluence, while higher fields resulted in frequency increases as excitation strength increased.
The researchers describe this behavior as laser-induced on-demand frequency tuning of coherent magnons in a nanometer-thick magnet at room temperature.
Modeling and simulations indicate that the effect does not arise from nonlinear interactions caused by large populations of magnons.
It is rather a balance between the magnetic anisotropy and the external field, temporarily altered by optical heating.
Simply put, researchers have found a way to use brief flashes of light to increase or decrease the magnetic behavior of a material thinner than a human hair while operating at room temperature.
This points to a future in which magnetic components in business computers and storage devices could be adjusted more quickly and with less energy.
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