Lasers could pave way for really fast disk drives

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New research could lead to hard disk drives capable of transferring data up to 100 times faster than a conventional hard drive.

Scientists working at Radboud University Nijmegen in the Netherlands have discovered that instead of using a magnetic head found in virtually all hard disk drives, polarised light could be used to flip the magnetic orientation of a bit from one to zero or vice versa.

Tests in the lab found that this laser light could change bits up to 100 times faster than the magnetic heads of a normal drive. The research could revolutionise the disk drive industry and give flash memory a run for its money. The tests used an amorphous ferromagnetic alloy, called GdFeCo, widely used in magneto-optical recording and known for its strong magneto-optical effects.

The researchers managed to transfer data in around 40 femtoseconds (a femtosecond is a quadrillionth of a second). The whole thing works because the photons of the laser light have angular momentum and this allows interaction with the platters of a disk drive. The laser heats up each bit on the hard drive with just enough energy to change its polarity, thereby storing data.

"This optically induced ultra-fast magnetisation reversal previously believed impossible is the combined result of femtosecond laser heating of the magnetic system to just below the Curie point, and circularly polarised light simultaneously acting as a magnetic field," said the researchers in an abstract of the research to be published in Physical Review Letters.

"This finding reveals an ultrafast and efficient pathway for writing magnetic bits at record-breaking speeds."

At present, the scientists still have to overcome the problem of the size of the laser's footprint compared to that of a normal magnetic head. The laser pulse hitting the disk is 5 microns wide, which is a lot larger than the footprint of a conventional head. According to one of the authors of the report Daniel Stanciu, the researchers are refining their techniques and this should see a reduction in the laser's footprint to just 10 nanometers, which would pave the way for use in storage devices.

The researchers said they hoped the observations from the experiments would lead to a "better understanding of the interaction of light with magnetic systems on ultrashort time scales."

More on the research can be found here.

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