Ultra High speed Process

Researchers at Sun Yat-Sen University in China have demonstrated a way to record on ferromagnetic films using laser-assisted ultrafast magnetization reversal dynamics. The development will allow for practical use of new technology for recording more than 6,000 terabits (6 petabits) of data on a single 5-inch disc, using ultra-high-density magneto-optical storage devices.

The new ultrafast recording technique uses “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. The researchers showed that the magnetization reversal could occur on 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 — at least thirty times faster than that of present hard disks in computers.

Laser-assisted magnetic recording was 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 Tianshu Lai, “and the genuine thermo-magnetic recording should happen within several tens to hundreds of picoseconds when we apply a smaller magnetic field than the coercivity of the recording films.”