Magnets, how do they work? Researchers at MIT have recently discovered that we might not have the firm grasp of magnetism once assumed. Past experiments have occasionally hinted at a bizarre phenomenon that caused thin magnetic films to flip polarity in the wrong direction — against the electron flow. Now the team from MIT has published a paper detailing the effect, and it could have a huge impact on storage technology.

Seeing a magnetic pole going in the wrong direction is a rare occurrence, so researchers have been understandably curious about the cause of this effect. Geoffrey Beach and his team at MIT have found that it’s not the magnetic material that’s responsible for the flipping pole, it’s the metal it is placed next to.

Beach used very thin films of ferromagnetic material to work out the specifics. When this film was placed on a slab of platinum and exposed to a current, it exhibited the backwards magnetic pole (or spin orientation). Move it over to a backing of tantalum, and the poles go in the correct direction again. Here is where the plot thickens: both platinum and tantalum are nonmagnetic, so how could they affect the magnetic properties of the film?

The mechanism relies on the way a spin orientation behaves in a very thin magnetic film. In most materials, the direction of pole changes is essentially random over time. With thin materials, all the poles are aligned. The current applied can push the magnetic domains with more or less force depending on the nonmagnetic material it is passing through. Platinum, for example, allows the current to bowl over the spin orientation of the magnetic film to the “wrong” side.

So how does this change storage technology? All magnetic storage media are based on the arrangement of magnetic domains. Positive and negative alignments in a magnetic material make up the ones and zeros that describe your favorite cat GIF, or that video you took on vacation. With this effect, small amounts of power can change the spin orientation of the film dramatically. Thus, it is incredibly high efficiency.

Beach and his team suspect that magnetic storage based on these films could be 10,000 times more energy efficient than traditional technology. Thin magnetic films could be used to provide dense, low-energy storage for both hard drives and solid state systems. This could mean dramatic power savings for mobile devices, which rely on NAND flash memory to store data.

This new class of magnetic material is not even a science-fiction proposition — it is completely compatible with present day manufacturing technology. Manipulation of magnetic domains on this scale was unthinkable even a few years ago, and the benefits could be enormous. Beach suggests thin magnetic films could find their way into consumer storage technology sooner than you think.

Nature Materials: dx.doi.org/10.1038/nmat3675 – “Current-driven dynamics of chiral ferromagnetic domain walls”

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