- Researchers demonstrate room-temperature laser control of magnons in thin magnetic materials
- Visible light pulses adjust magnetic frequencies without cryogenic conditions
- Nanoscale magnets hold promise for faster storage and silicon-free computing
Researchers have demonstrated a new way to tune the magnetic behavior of extremely thin materials using laser pulses visible at room temperature.
The work focuses on the control of magnons, which are collective spin excitations that play a key role in magnetic devices.
The study, published in Natural communicationsshows that nanometer-thick magnets can have their magnon frequencies adjusted up and down on demand. The material used is only 20nm thick, making it compatible with dense electronic designs.
A myriad of possibilities
Magnons are already at the heart of technologies such as hard drives and emerging concepts of spin-based computing. Being able to control their frequency precisely has long been considered a requirement for practical devices.
In previous experiments, similar effects had only been achieved using mid-infrared lasers, cryogenic temperatures or bulky materials. These constraints limited any realistic path to commercial use.
In this new work, the researchers instead used short laser pulses of visible light combined with a modest external magnetic field of less than 200 mT. This made it possible to shift the magnon frequencies by up to 40 percent from their original value.
Experiments were performed at room temperature using a bismuth-substituted yttrium iron garnet film grown on a scandium gallium gadolinium garnet (GSGG) substrate. The film’s low damping and strong magneto-optical response proved essential.
By adjusting the laser intensity and the magnetic field strength, the team was able to reliably choose whether the magnon frequency increased or decreased.
This level of control comes from the interaction between optical heating, magnetic anisotropy and applied field.
The laser pulses act as a high-speed adjustment mechanism rather than just a heat source. They temporarily modify the magnetic rigidity of the material, which directly modifies the speed of oscillation of the magnons.
Because the effect operates on nanosecond time scales, it opens the door to magnetic logic elements that can be reconfigured almost instantly.
Such devices could avoid some of the heat and scaling limitations faced by silicon electronics.
The combination of room temperature operation, visible light control and nanoscale thickness means this approach could be suitable for future spin-based storage, signal processing and computing systems.
Simply put, the research could help make everyday technology faster and more efficient, with one of the most obvious uses being data storage.
Hard drives and large cloud servers rely on magnetic materials, and being able to control them more precisely with light could allow data to be written and moved much faster than today.
It could also lead to the creation of new types of computer chips that use magnetism instead of electric current to process information.
These would produce less heat and use less power, which could lead to quieter laptops, longer battery life and – the holy grail for hyperscalers – data centers that are cheaper to operate.
Another possible use is hardware that can change what it does on the fly. Instead of building a chip for a single task, light could be used to change its behavior almost instantly, allowing a single piece of hardware to perform different tasks.
Since the effect works at room temperature and in layers thinner than a human hair, it’s also not limited to lab experiments, meaning it could eventually be integrated into the phones, computers, and portable storage systems that people already use every day.
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