Researchers Use Laser-Like X-ray Beams to See Different Behaviors of Elements in Important Alloy

Achievement date: 
2013
Outcome/accomplishment: 

Researchers affiliated with the Center for Extreme Ultraviolet Science and Technology (ERC EUV), an NSF-funded Engineering Research Center headquartered at Colorado State University, used the world’s fastest light source–bursts of laser-like X-ray beams–to observe unique phenomena. Scientists at the University of Colorado (Boulder) and the National Institute of Standards and Technology could see microscopic bar magnets in an important magnetic alloy of iron and nickel (permalloy) spinning differently immediately after being exposed to laser light (in the first few quadrillionths of a second, which is the first 10 femtoseconds [a femtosecond is 10-15 sec.]).

Impact/benefits: 

The scientists learned that iron spins reacted slightly faster to light than the nickel spins (see accompanying figure), suggesting that the iron spins "see" light much more readily than the nickel spins. This finding could lead to faster and “smarter” computers because it suggests that the magnetic alloys in hard drives could be engineered to enhance delivery of optical energy to the spin system. Until now, it was assumed that all the spins in a strong magnet behaved in the same way.

Explanation/Background: 

Strong magnets exist only because all the spins in a magnet, each of which is like a very small bar magnet with a north and south pole, are lined up to point in the same direction, much like members of a football band who are marching in unison. Many technology experts believe that next-generation computer disk drives will use optically-assisted magnetic recording to store more data, more efficiently, and with faster access. However, many questions remain about how the delivery of optical energy to the magnetic system can be optimized for maximum drive performance.