TU/e combines light and magnetism for storage

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Researchers at Eindhoven University of Technology have succeeded in describing magnetic racetrack memory with short light pulses. The method works quickly and is energy efficient, according to the scientists.

The method the researchers demonstrated has great potential for use in future photonic computer chips, they say. Writing bits could be a hundred to a thousand times faster compared to current hard disks, they predict. Because less electronics are needed, the technology could also become more energy-efficient.

The basis of the invention is the use of ultra-short light pulses to determine the direction of the magnetization and thus to write bits onto a material. This form of optical switching has been used for about ten years, but until now requires several light pulses instead of a single one to switch a magnetic pole, at the expense of speed and energy consumption.

The Eindhoven researchers used synthetic ferrimagnets as the material. With this, they managed to switch a magnetic pole with a single pulse of light from a femtosecond laser. This type of laser emits very short pulses with a duration of several to hundreds of femtoseconds.

The team combined the laser with so-called racetrack memory. This type of memory works with small magnetic domains that move along a read and write mechanism to be read and manipulated. In the Eindhoven system, the bits are transported through a magnetic microwire using an electric current, whereby the laser can describe new bits in the empty spaces with light.

“This ‘on the fly’ copying of information between light and magnetic race tracks, without any intermediate electronic steps, is like jumping back and forth between two moving high-speed trains, instead of having to change trains at a station,” TU/e ​​describes. Professor Bert Koopmans. For practical application in computer chips, the researchers must reduce the microwires to nanowires and develop a method for reading them.

The research team, consisting of PhD student Mark Lalieu, Reinoud Lavrijsen and Koopmans, published the work under the name Integrating optical switching with spintronics in Nature Communications.

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