The magnetism that causes compasses to point North and allows hard drives to store data ultimately boils down to the orientation of electrons. These, and other, elementary particles have a quantum mechanical property called spin, which directly relates to magnetism as aligned spin states combine to create a magnetic field. Sometimes electrons choose to align in a vortex, spinning around in a disk, with a spike in the center, to keep everything aligned, and now researchers at Berkeley Lab are looking at this structure to double how much information magnetic memory can hold, while also making it easier to write to.
While many data storage technologies rely on some kind of binary system, these vortices have four states they can exist in, allowing them to store multiple bits. The direction of the electrons' spins in the disk can represent one bit, while the direction of the spike can represent another. What the Berkeley Lab researchers have done is directly image the vortices after being hit with a magnetic field. This allowed them to determine what geometries made it easiest to rewrite the states of the vortices. Typically this would require strong magnetic fields, but the researchers found that weaker magnetic pulses can flip the bits quite quickly, if the vortices are small enough.
While this technology may one day greatly increase the data density for magnetic storage, while also improving its energy efficiency, that day is not here as we still need to learn how to change the direction of the spike and the disk at the same time. The researchers are also considering was to potentially build logic devices from the vortices, allowing them to perform computations.
Source: Berkeley Lab