- Light can rapidly change magnetic behavior, suggesting faster data storage methods
- Researchers controlled magnets thinner than a hair without extreme conditions or cooling
- The laser pulses altered the magnet's behavior by up to forty percent at room temperature
Modern digital life depends largely on the efficiency with which information can be stored and processed.
From hard drives to emerging computing systems, magnetism remains critical to these technologies because it governs how bits are written, moved, and retained.
Engineers have long sought ways to tune magnetic behavior quickly and precisely without relying on very hot electrical currents.
Beyond impractical 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 demonstrated that laser pulses could influence magnetic excitations, but only in bulk materials, at very low temperatures, or using specialized mid-infrared laser systems.
These limitations make it difficult to imagine integration into everyday hardware, as such conditions conflict with scalable manufacturing and practical operation of devices.
In this context, German, Swiss and Italian researchers recently reported experimental results indicating that such limitations may not be inevitable.
His study, published in Nature 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 stress forces the magnetization to orient out of plane, creating a well-defined magnetic state before excitation.
Using femtosecond pump probe techniques, the researchers monitored how the magnetization responded after brief pulses of visible light hit the material.
Because the photon energy exceeds the bandgap of the material, laser-induced heating rather than selective resonant excitation dominates.
The team applied an external magnetic field below 200 mT to control the initial magnetic configuration.
Under these conditions, the researchers observed that 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 depended on both the applied magnetic field and the laser fluence.
Lower fields favored frequency reductions with moderate fluence, while higher fields led to frequency increases as excitation strength increased.
The researchers describe this behavior as a laser-induced frequency tuning on demand of coherent magnons in a nanometer-thick magnet at room temperature.
Models and simulations indicate that the effect does not originate from nonlinear interactions caused by large populations of magnons.
Rather, it arises from a balance between magnetic anisotropy and the external field, temporarily altered by optical heating.
Simply put, the researchers found a way to use brief flashes of light to increase or decrease magnetic behavior in a material thinner than a human hair while operating at room temperature.
This points to a future in which magnetic components in companies' computers and storage devices could adjust faster and with less energy.
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