Laser-induced heat can record information
YORK, UK – A revolutionary magnetic recording method that uses an ultrashort heat pulse to switch magnetic polarity enables information processing hundreds of times faster than current hard-drive technology.
Previously, it was believed that magnetic recording required the application of an external magnetic field, which inverted magnetic poles. The stronger the applied field, the faster a magnetic bit of information could be recorded.
Experimental images showing the repeated deterministic switching of nano islands. Initially, the two nano islands have different magnetic orientations (black and white, respectively). After the application of a single pulse, the magnetic direction of both islands changes. Further pulses repeat the process, switching the magnetic state back and forth. Courtesy of Johan Mentink and Alexey Kimel, Radboud University Nijmegen; and Richard Evans, University of York.
But scientists at the University of York and a team of researchers from Spain, Switzerland, Ukraine, Russia, Japan and the Netherlands discovered that they could record information using only heat – a previously unimaginable scenario.
“For centuries, it has been believed that heat can only destroy the magnetic order,” said Dr. Alexey Kimel of the Institute of Molecules and Materials at Radboud University Nijmegen in the Netherlands. “Now we have successfully demonstrated that it can, in fact, be a sufficient stimulus for recording information on a magnetic medium.”
Visualization of ultrafast heat-induced magnetic switching. Before the laser pulse, the two components of the ferromagnetic material, Fe (blue) and Gd (red), are aligned antiparallel to each other. The 60-fs laser pulse rapidly heats the material, and this alone induces a transient ferromagneticlike state, where the Fe and Gd moments are aligned in parallel. After the laser pulse, the components relax to their usual state, completing a single switching event in less than 5 ps. Courtesy of Richard Evans, University of York.
They demonstrated that the inversion of magnetic poles can be achieved with an ultrashort heat pulse, harnessing the power of much stronger internal forces of magnetic media.
“Instead of using a magnetic field to record information on a magnetic medium, we harnessed much stronger internal forces and recorded information using only heat,” said Thomas Ostler, a University of York physicist. “This revolutionary method allows the recording of terabytes (thousands of gigabytes) of information per second, hundreds of times faster than present hard drive technology.”
The research appeared in Nature Communications (doi: 10.1038/ncomms1666).
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