In theJournal of Applied Physics, researchers at Sun Yat-Sen University in China have demonstrated a way to record on ferromagnetic films using a laser-assisted ultrafast magnetization reversal dynamics.
The technique uses so-called time-resolved polar Kerr spectroscopy combined with an alternating magnetic field strong enough to re-initialize the magnetization state of gadolinium-iron-cobalt (GdFeCo)thin films. Tianshu Lai and colleagues showed that the magnetization reversal could occur in a sub-nanosecond time scale, which implies that next- generation magneto-optical storage devices can not only realize higher recording densities but also ultrafast data writing of up to a gigahertz. Such speed is at least thirty times faster than that of present hard disks in computers.
Laser-assistedmagnetic recordingwas demonstrated on a sub-picosecond time scale under a saturated external magnetic field."We found that the rate of magnetization reversal is proportional to the external magnetic field,"says Lai,"and the genuine thermo-magnetic recording should happen within several tens to hundreds of picoseconds when we apply a smallermagnetic fieldthan the coercivity of the recording films."
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