I don’t know why, but I am always impressed with the latest new milestone reached or breakthrough achieved with magnetic storage devices (you know, the hard drive in your computer). Maybe it’s because I also recall these stories alternating with stories that some finite limit or other has been reached and nobody will ever make anything that can store more data. They seem to go in cycles, and I suppose it’s more about the lack of any real understanding on the part of “technology” writers who are satisfied with rewriting PR releases than it is about the actual R&D.
The author at Next Big Future, who does actually seem to know what the hell he’s writing about, had a post earlier this week about the imminent arrival of magneto-optical storage devices that can squeeze 6 petabits of data into a 5-inch disk (to reframe “6 petabits” into a unit you probably recognize, that’s the equivalent of 786,432 gigabytes). But even more impressive than the raw size of the storage is that the mechanism of the drive can read and write data 30 times faster than your garden-variety hard drive, which is vital to making such a massive amount of storage usable in a practical way.
But I have to admit that the pull quote he used from the journal article that describes the technology that makes this all possible was next-to-incomprehensible to me. Here you have a go at it:
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-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 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.
Ultrafast dynamics of genuine magneto-optical recording across ferrimagnetic compensation points is demonstrated in GdFeCo films using time-resolved polar Kerr spectroscopy combined with a laser-synchronized sinusoidal alternating magnetic field which can reinitialize irreversible initial magnetization state to laser radiating. The external field dependence of magnetization reversal dynamics is measured and shows that reversal rate accelerates with increasing external fields. Analysis of the magnetization reversal dynamics with Bloch equation shows the magnetization reversal rate is linearly dependent on the external fields within experimental errors, which supports quantitatively that the mechanism of magneto-optical recording in rare earth-transition metal ferromagnetic films is related to the formation and growth of the reversed domains. It is also shown that nucleation field is obviously larger than hot coercivity shown in the anomalous hysteresis loop.
If you say so, dude, but someone’s going to max that out with porn and mp3s in, like, two weeks.



