Magnetics Business & Technology - Spring 2015 - (Page 4)

EDITOR'S CHOICE Noncommittal Material Could Make for Hypersensitive Magnetic Direction Detector While the mysterious, unseen forces magnets project are now (mostly) well-understood, they can still occasionally surprise us. For instance, thin films of cobalt have been observed to spontaneously switch their poles, something that typically doesn't happen in the absence of an external magnetic field. Physicists at the National Institute of Standards and Technology (NIST) and the University of Maryland (UMD) have measured this phenomenon on the largest scale yet. Most magnets are "permanent," meaning a magnetic field of some strength must be applied to reverse their north and south poles. This permanence enables the billions of tiny magnets in hard drives to re(Left) Polarization sensitive light microscopy shows the liably store data. And smartphone pattern of north poles (black) and south poles (white) compasses use nanomagnetic sen- on thin layer of magnetic cobalt. (Right) The researchers sor technology to detect the Earth's found that the pattern of north poles and south poles magnetic field. spontaneously fluctuates over time. Strongly fluctuating At the present time, creating and areas are encoded here as brighter colors. Researchers detecting these magnetic fields hope to use this data to make more sensitive magnetic takes a good deal of energy. Making materials whose domains can be flipped more energy efthese devices more energy efficient ficiently, a boon to those with rapidly dying smartphone batteries. Images show an area approx. 75 micrometers will require more sensitive magnets across. Credit: Balk/NIST that can be influenced by small magnetic or electric fields. However, as these magnets become more sensitive, they also become more unstable, flipping from north to south and back, even with no magnetic field. The NIST/UMD team mapped out this instability in a film of cobalt, only a few atoms thick, and determined the conditions under which the instability arises. They hypothesize that the development of magnetic technology will benefit from their continuously flipping cobalt films, which can function as extremely sensitive magnetic test beds. Many proposed devices implement layers of ferromagnetic material that must be individually controlled by electric fields to be useful. According to NIST researcher Andy Balk, however, most magnetic materials are too stable to be influenced at all by electric fields, and researchers have no way of knowing if their proposed devices are even close to working. "As an alternative," Balk said, "we could make a proposed magnetic device from our unstable film. This way, even if the film were influenced only a very small amount, we would see, for example, slightly more north flips than south flips, and we would know we are on the right track." The current measurements were done with video-rate Kerr microscopy, a form of polarized light microscopy that can image the fine-grained details of a material's magnetic state. The scientists found that if undisturbed by outside influence, the magnetic fluctuations in the thin cobalt film interact with each other; a fluctuation from north to south will always have a corresponding nearby fluctuation from South to North. Interestingly, these fluctuations exhibit scale invariance, meaning that their behavior is the same regardless of the length scale on which they are observed, a property they share with otherwise unrelated phenomena such as earthquakes and crumpling paper. The researchers are continuing this work at NIST by developing these thin films into sensitive field detectors for computing and biomedical applications. Hybrid Multiferroics for Data Storage and New Wireless Applications To exploit and control magnetism, technology often relies on electromagnets, which limit hardware configurations due to their size and energy consumption. As an alternative, scientists are beginning to develop hybrid nanomaterials that are responsive to both electric and magnetic fields. These materials can save energy and space, and are opening doors to a wealth of new technological applications Creating materials that can be influenced by both magnetic and electric forces, so called 'multiferroics', is an emerging field that is currently being addressed mainly by academics, al- 4 Magnetics Business & Technology * Spring 2015 Volume 14, Issue 1 Editor & Publisher David Webster Director of Content Nick Depperschmidt Senior Editor Shannon Given Associate Editor Heather Williams Contributing Editor Stan Trout News Editors Sue Hannebrink, Scott Webster William Massey, Melissa Cooley Dave Nosak Director of Support Services/Circulation Marc Vang Databases/Directories Ross Webster Advertising Sales and Marketing Scott Webster, Advertising Sales Manager Webmaster CJ Brewer Administration Marsha Grillo, Director Magnetics Business & Technology (ISSN #1535-1998) is a publication of Webcom Communications Corp. 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Table of Contents for the Digital Edition of Magnetics Business & Technology - Spring 2015

Editor's Choice
First-Order-Reversal-Curve Analysis of Multi-Phase Ferrite Magnets
Magnetics Design Tool for Power Applications
Magnet Inspection Tool with High Magnetic and Mechanic Accuracy
Research & Development
Electromagnetics
Software & Design
Industry News
Marketplace / Advertising Index
Spontaneous Thoughts: The Patent Challenge

Magnetics Business & Technology - Spring 2015