In the race to develop the next generation of storage and recording media, a major hurdle has been the difficulty of studying the tiny magnetic structures that will serve as their building blocks. Now a team of physicists at the University of California, Davis, has developed a technique to capture the magnetic âfingerprintsâ of certain nanostructures â even when they are buried within the boards and junctions of an electronic device.
Due to the miniscule physical dimensions of nanomagnets â some are as small as 50 atoms wide â observing their magnetic configurations has been a challenge, especially when they are not exposed but built into a functioning device.
To tackle this challenge, Liu and three of his students, Jared Wong, Peter Greene and Randy Dumas, created copper nanowires embedded with magnetic cobalt nanodisks. Then they applied a series of magnetic fields to the wires and measured the responses from the nanodisks. By starting each cycle at full saturation â that is, using a field strong
enough to align all the nanomagnets â then applying a progressively more negative field with each reversal, they created a series of information-rich graphic patterns known to physicists as âfirst-order reversal curve (FORC) distributions.â