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This story is from the category Computing Power
Date posted: 09/08/2012 The phenomenon in ferromagnetic nanodisks of magnetic vortices -- hurricanes of magnetism only a few atoms across -- has generated intense interest in the high-tech community because of the potential application of these vortices in non-volatile Random Access Memory (RAM) data storage systems. New findings from scientists at the U.S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory (Berkeley Lab) indicate that the road to magnetic vortex RAM might be more difficult to navigate than previously supposed, but there might be unexpected rewards as well. In an experiment made possible by the unique X-ray beams at Berkeley Lab's Advanced Light Source (ALS), a team of researchers led by Peter Fischer and Mi-Young Im of the Center for X-Ray Optics (CXRO), in collaboration with scientists in Japan, discovered that contrary to what was previously believed, the formation of magnetic vortices in ferromagnetic nanodisks is an asymmetric phenomenon. It is possible that this breaking of symmetry would lead to failure in a data storage device during its initialization process. "Our experimental demonstration that the vortex state in a single magnetic nanodisk experiences symmetry breaking during formation means that for data storage purposes, there would probably need to be a lengthy verification process to correct for errors," Im says. "On the plus side, non-symmetric behavior creates a biasing effect that could be applied to a sensor or a logic device." "Our study is also a nice example of mesoscale science, which brings the nanoscience of the last decade to the next level," Fischer says. "Mesoscale phenomena encompass complexity and functionality over various length scales." Im and Fischer describe this study in a paper published in the journal Nature Communications. The paper is titled "Symmetry breaking in the formation of magnetic vortex states in a permalloy nanodisk." Co-authoring this paper were Keisuke Yamada, Tomonori Sato, Shinya Kasai, Yoshinobu Nakatani and Teruo Ono. Magnetic vortex states are generated in ferromagnetic nanodisks because the spin of electrons, which gives rise to magnetic moments, must follow the shape of the disk to ensure closure of magnetic flux lines. This results in the curling of the in-plane magnetization flux lines. At the center of these curling flux lines is a needlelike core, an "eye-of-the-hurricane" that points either up or down with respect to the surface plane of the nanodisk. "The magnetization of the ferromagnetic nanodisk therefore has two components, the up or down polarity of the core and the chirality (rotation) of the in-plane magnetization, which can be either clockwise or counter-clockwise," Im says. "It has been proposed that these four independent orientations can be used to store binary data in novel non-volatile storage devices." See the full Story via external site: www.sciencedaily.com Most recent stories in this category (Computing Power): 17/05/2013: Data storage: Synchronized at the write time |
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