On a recent spring day a buzz of excitement filled the air at the Institute for Magnetics Research (IMR) as GW faculty members, Edward Della Torre, director of GW’s Institute for Magnetic Research and professor, and Lawrence H. Bennett, research professor, explained how they detected the unexpected behaviors of magnetic nanostructures and the types of practical applications. Several doctoral students listened attentively and posed questions while trying to grasp the relevance of the breakthrough.

Magnetic nanostructures, extremely small magnetic particles around one billionth of a meter in size, have practical applications for manufacturers of products using magnets, such as computer hard drives, as well as broader implications for the fields of physics, chemistry, and engineering.

“One practical application of our discoveries would be to use this information to improve the way the life cycle of computer hard drives is modeled,” said Della Torre. “The magnets in hard drives effect whether the information on a hard drive will be stored for 10 minutes, 10 days, or 10 years, so it is important to both manufacturers and consumers to have a model that rapidly and accurately predicts how long a hard drive will last.”

The observations are especially significant because they expand the understanding of well accepted laws of physics. When Della Torre and Bennett began discussing their findings with colleagues in the field the reactions were of astonishment and disbelief. They questioned, “How can it be?”

Although the Bloch T^3/2 law of physics states the strength of a magnet is a function of temperature, they found this didn’t hold always hold true. For example, the law says that when temperature goes ↑, magnetization goes ↓ and when the temperature goes ↓, magnetization goes ↑.

When they plotted magnetization as a function of decreasing temperature the curve was no longer evenly sloped as predicted. Rather it showed a subtle upturn of the magnetization curve in the 10-50 K temperature range. They explain these visible anomalies in the law using the Bose-Einstein condensation theory, first predicted by Satyendra Nath Bose and Albert Einstein in 1924. Bennett drew the expected and actual curves on a flipchart to illustrate their discovery.

Della Torre and Bennett’s article about these observations, “Extension of the Bloch T^3/2 Law to Magnetic Nanostructures: Bose-Einstein Condensation” was published April 15, 2005 in Physical Review Letters, a prestigious physics journal published by The American Physical Society. It is the collaborative work of the pair, along with their colleague R.E. Watson of the Brookhaven National Laboratory, Department of Physics in Upton , N.Y.

About the Institute for Magnetics Research:
GW’s Institute for Magnetics Research, located at the University’s Virginia Campus, focuses its work on modeling, experimental measurements, and the use of magnetic materials. The materials most commonly studied are magnetic recording media, magneto-optical media, and magnetostrictive materials. Applications include computer hard drives, floppy disks and read/write memories, microwave devices, magnetostrictive transducers, and magnetic refrigeration. The institute has conducted research projects with the National Institute of Standards and Technology in Gaithersburg, the National Science Foundation, Bureau of Engraving and Printing, DARPA, IBM, Fuji , and ANSYS Software.