Advances in Engineering Advances in Engineering features breaking research judged by Advances in Engineering advisory team to be of key importance in the Engineering field. Papers are selected from over 10,000 published each week from most peer reviewed journals.
Journal of Magnetism and Magnetic Materials, Volume 331, April 2013, Pages 21-23
T. Blachowicz, A. Ehrmann
Institute of Physics, Silesian University of Technology, 44-100 Gliwice, Poland
Faculty of Textile and Clothing Technology, Niederrhein University of Applied Sciences, 41065 Mönchengladbach, Germany
Abstract
Six stable states at remanence were identified in iron wire samples of 6-fold spatial symmetry using micromagnetic simulations and the finite element method. Onion and domain-wall magnetic states were tailored by sample shape and guided by an applied magnetic field with a fixed in-plane direction. Different directions of externally applied magnetic fields revealed a tendency for stability or nonstability of the considered states.
Addition Information
Highly symmetric six-fold wire systems with wire lengths of 70 nm and widths 10 nm, coupled by half-balls of diameter 20 nm, exhibit a novel multilevel behavior in micromagnetic simulations. “Snapshots” of the magnetization during the reversal processes reveal the existence of four onion states and two domain wall states for a complete hysteresis loop.
Compared with former examinations of fourfold wire systems (J. Appl. Phys. 110, 073911 (2011)), the intermediate levels, entered during the magnetization reversal process from positive to negative saturation and vice versa, are only stable for a chosen range of field values and a given range of sample orientations. However, for some orientations, six stable and distinguishable magnetization values at vanishing external field are possible; importantly, decreasing the route of the magnetic field intensities leading to zero value is a reversible process.
These stable intermediate states can be utilized in a novel design of bit-patterned magnetic media. While decreasing the size of each bit area more and more is limited by physical and technical problems, nano-systems with two, four, six, or more stable states at vanishing external magnetic field allow for building new storage media systems with additional bits per area, thus increasing the data storage density by a factor of two, three or even more.
