July 5, 2007 8:08 AM PDT
Laser innovation speeds up hard disks
A paper published by Daniel Stanciu of the Institute for Molecules and Materials at Radboud University Nijmegen describes a method of using ultrarapid pulses of polarized light to heat up areas on a hard disk and, crucially, using the same light to change the polarity of those areas. The polarity of the disk storage medium is reversed by reversing the polarity of the laser pulses, according to a report in Science.
Stanciu was not available for comment, but in the abstract accepted for publication by the Physical Review Letters, he wrote, "We experimentally demonstrate that the magnetization can be reversed in a reproducible manner by a single 40-femtosecond circularly polarized laser pulse, without any applied magnetic field."
This optically induced, ultrafast magnetization reversal, he says, was previously believed impossible, and it is the combined result of femtosecond laser heating of the magnetic system to just below the Curie point, and circularly polarized light simultaneously acting as a magnetic field.
Similar effects have previously been used in magneto-optical storage devices, but those used a magnetic field applied by conventional means, not by the laser.
According to Science, Stanciu expects to see a working prototype within a decade.
Matt Loney of ZDNet UK reported from London.
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