Did you know oftentimes, magnets are not actually magnetic when they are in the early stages of production? Instead, they are activated with a magnetizer (check out our video here to watch this process). If magnets can become magnetized, it shouldn’t come as a surprise, then, that magnets can just as easily become demagnetized.

We already know that magnets can become demagnetized for a lot of reasons, such as volume loss from corrosion, high heat, heavy impact, or just over time. Scientists at CU Boulder are currently investigating a new way that magnets are becoming demagnetized though -- being shot by a laser.

What Scientists Know

When you hit an ultra-thin magnet with a laser, it appears to demagnetize. What’s more interesting, though, is that the magnets are seen to recover after, with magnets having been found to regain their properties in a fraction of a second.

The Research

CU Boulder’s Ezio Iacocca, Mark Hoefer, and their colleagues’ conducted experiments at Stanford University’s SLAC National Accelerator Laboratory on magnets and laser beams. They’ve found that magnets are seemingly recovering (re-magnetizing) in the first 20 trillionths of a second after a magnetic, metal alloy is hit with a short, high-energy laser.

Iacocca explained how magnets are generally pretty organized, with their atomic building blocks having “spins” that tend to point in the same direction, either up or down. When a magnet is blasted with a laser (in a short enough laser pulse) Iacocca said, the spins within the magnet will no longer point just up or down, but in all different directions -- this is what cancels out the metal’s magnetic properties.

According to a study published in Nature Communications, the spins within the post-zapped magnets behaved like fluids, moving around and changing their orientation like waves crashing in an ocean. It’s important to note that the metals themselves didn’t turn into liquid. “We used the mathematical questions that model these spins to show that they behaved like a superfluid at those short timescales,” said Hoefer, a co-author of the new study. Their magnetic properties begin to form “droplets” similar to “what happens when you shake up a jar of oil and water.”

After some time passes, those spins start to settle down, forming small clusters with the same orientation -- in essence, “droplets” are formed in which the spins all pointed up or down again.  Hoefer added that a zapped magnet doesn’t always go back to the way it once was. When magnets were zapped with a larger pulse laser, some magnets were shown to flip their spins -- they switched from up to down.

Engineers already take advantage of that flipping behavior to store information on a computer hard drive in the form of bits of ones and zeros. With this new information though, Iacocca said if researchers can figure out ways to do that flipping more efficiently, they might be able to build faster computers.

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