Flipping Bits In Picoseconds, Not Nanoseconds
There is still life left in spinning rust; even though you have likely moved on to SSDs of various flavours in your rig there are still many that depend on HDDs every day. That is what spurs the continuing research into making faster and higher density drives, such as the discovery by Delft University of Technology in the Netherlands that light-induced lattice vibrations can vastly increase the speed at which you can write to a hard drive’s platter.
They bombarded platters made of a crystal lattice of dysprosium orthoferrite (DyFeO3) with intense (> 10 MV cm–1) mid-infrared laser pulses to magnetize or demagnetize tiny portions of the platter, similar to more traditional writing techniques. The flip happens a wee bit faster than with traditional magnetic pulses, to the tune of 1000 times faster in fact. Even if the efficiency of the flipping is reduced by a factor of 10 or 100 in real world usage, this would represent a huge performance increase for hard drives.
The way this works is not just due to the use of light to flip the lattice vibrations in the dysprosium orthoferrite, but also because of the actual properties of the material. DyFeO3 is an antiferromagnetic material, not a magnetic material as current drives are made from. This means that the electron spins in DyFeO3 are antiparallel, not parallel so there is no net magnetization on a platter. Flipping one small area of the drive to make it ferromagnetic will have no effect on neighbouring crystal lattices. That will allow for higher densities than traditional drives, as well as making this type of drive much more stable as well.
We won’t be seeing this type of technology any time soon but it is wonderful to see continuing research on hard drives in a time when flash rules the roost. You can read a much better description of the research over at PhysicsWorld.
Because these magnetic pulses require a substantial electrical current, the data-writing process dissipates significant amounts of energy. It is also relatively slow, with a complete spin flip taking tens of nanoseconds (1 ns = 10-9 s).