|arya||Date: Friday, 11-January-2013, 3:48 PM | Message # 1|
In this artist rendering, tiny magnetic vortices form on nanodisks, with each disk having a diameter of about 100 nanometers. Each vortex is directed either upwards or downwards. The Argonne study looked at the interaction between pairs of these nanodisks. Credit: Sander Munster, Dresden University of Technology
(Phys.org)—In science, just like in life, sometimes creating the most effective organization depends on being able to handle just a bit of chaos first.
Scientists at the U.S. Department of Energy's Argonne National Laboratory have used alternating magnetic fields to control the behavior of "spin vortices" trapped in small dots made from iron and nickel that can be magnetized in two separate ways. While the majority of these structures are magnetized in-plane either clockwise or counter-clockwise, a tiny region at their centers – the vortex core – is magnetized out of plane, either up or down.
"If you were able to visualize it, it would look like a funnel," said Argonne materials scientist Valentyn Novosad.
Novosad and postdoctoral researcher Shikha Jain wanted to find a way to control the magnetic states of pairs or even large groups of these dots that interacted with each other in a lattice.
In the resting state, the cores of the dots are randomly polarized. After applying an oscillating magnetic field to the pairs of dots, the researchers observed that the central cores began to switch back and forth repeatedly between up- and down-magnetizations – which Jain and Novosad characterized as "chaos."
Full article/read more/source - http://phys.org/news/2013-01-chaotic-vortices-memories.html