Nanomagnetic fingerprints may provide boost for next-gen information storage media

January 31st, 2009 - 3:53 pm ICT by ANI  

Washington, Jan 31 (ANI): A team of physicists at the University of California (UC), Davis, has developed a technique to capture the magnetic fingerprints of certain nanostructures, which could provide a boost for next-generation information storage media.

The past decade has witnessed a thousand-fold increase in magnetic recording area density, which has revolutionized the way information is stored and retrieved.

These advances are based on the development of nanomagnet arrays that take advantage of the new field of spintronics: using electron spin as well as charge for information storage, transmission and manipulation.

But, due to the miniscule physical dimensions of nanomagnets, observing their magnetic configurations has been a challenge, especially when they are not exposed but built into a functioning device.

You cant take full advantage of these nanomagnets unless you can see and understand their magnetic structures not just how the atoms and molecules are put together, but how their electronic and magnetic properties vary accordingly, said Kai Liu, a professor and Chancellors Fellow in physics at UC Davis.

This is difficult when the tiny nanomagnets are embedded and when there are billions of them in a device, he added.

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 that is, using a field strong enough to align all the nanomagnets then applying a progressively more negative field with each reversal, they created a series of information-rich graphic patterns known to physicists as first-order reversal curve (FORC) distributions.

According to Liu, Each pattern tells us a different story about whats going on inside the nanomagnets. We can see how they switch from one alignment to another, and get quantitative information about how many nanomagents are in one particular phase.

For example, whether the magnetic moments are all pointing in the same direction or curling around a disk to form vortices. This in turn tells us how to encode information with these nanomagnets, he added.

The technique will be applicable to a wide variety of physical systems that exhibit the kind of lag in response time as magnets, including ferroelectric, elastic and superconducting materials, Liu explained.

Its a powerful tool for probing variations, or heterogeneity, in the system, and real materials always have a certain amount of this, he said. (ANI)

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