Light Instead of Current: Switching Magnetic Domains express
In a thin nickel oxide film, magnetic regions are arranged in strict order like mosaic pieces. A single laser pulse instantly heats the material, and the mosaic falls apart: domains lose their orientation and mix. Scientists captured this process using magneto-optical imaging — a technique that reveals magnetic structure through changes in light polarization.
But the trick doesn't end there. If the laser beam doesn't just shine on one spot but slowly moves across the surface, it creates a temperature difference. This difference acts on domain boundaries like an invisible hand, nudging them sideways. By changing the direction of the beam's motion, the researchers reversibly switched domains by 90 degrees — all without a single wire or electric current.
This way of controlling magnetic order matters for future memory. Antiferromagnets don't produce an external magnetic field, so neighboring memory cells don't interfere with each other. And optical switching can be hundreds of times faster than current-induced magnetization reversal. The film again resembles a mosaic, but now its pattern can be changed with a single sweep of the beam, like an artist who doesn't touch the canvas with a brush but merely directs light.
Original abstract
as written by the authors arXiv:2604.05806
We demonstrate all-optical manipulation of magnetic domains in NiO/Pt and CoO/Pt thin films with insulating antiferromagnetic layers. Using magneto-optical birefringence imaging, we show that even a single laser pulse can thermally demagnetize the antiferromagnet, leading to a random redistribution of domains. By sweeping the laser beam, controlled domain wall motion is induced, enabling partial switching of the antiferromagnetic order. The behavior is captured by an analytical model in which temperature gradients generated by the moving beam exert a thermal pressure on domain walls in the form of a ponderomotive force. Importantly, the 90$$^{\circ}$$ domains can be reversibly toggled solely by reversing the direction of the thermal gradient, demonstrating all-optical switching without the need for electric currents. These findings establish a route toward ultrafast optical manipulation of fully compensated antiferromagnets, with potential impact on non-volatile memory technologies and antiferromagnetic spintronics.
Antiferromagnets barely respond to external magnetic fields, so their domains were long considered "invisible" to conventional methods. Magneto-optical imaging allowed them to be seen directly for the first time.
In Arthur C. Clarke's novel "The Light of Other Days," information is written by light directly into the structure of matter — similar to optical domain switching, only in science fiction it works at a distance and without heating.