Magnetization in narrow ribbons: Curvature effects

Yuri Gaididei, Arseni Goussev, Volodymyr P. Kravchuk, Oleksandr V. Pylypovskyi, J. M. Robbins, Denis D. Sheka*, Valeriy Slastikov, Sergiy Vasylkevych

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)

20 Citations (Scopus)
149 Downloads (Pure)

Abstract

A ribbon is a surface swept out by a line segment turning as it moves along a central curve. For narrow magnetic ribbons, for which the length of the line segment is much less than the length of the curve, the anisotropy induced by the magnetostatic interaction is biaxial, with a hard axis normal to the ribbon and an easy axis along the central curve. The micromagnetic energy of a narrow ribbon reduces to that of a one-dimensional ferromagnetic wire, but with curvature, torsion and local anisotropy modified by the rate of turning. These general results are applied to two examples, namely a helicoid ribbon, for which the central curve is a straight line, and a Mbius ribbon, for which the central curve is a circle about which the line segment executes a 180° twist. In both examples, for large positive tangential anisotropy, the ground state magnetization lies tangent to the central curve. As the tangential anisotropy is decreased, the ground state magnetization undergoes a transition, acquiring an in-surface component perpendicular to the central curve. For the helicoid ribbon, the transition occurs at vanishing anisotropy, below which the ground state is uniformly perpendicular to the central curve. The transition for the Mobius ribbon is more subtle; it occurs at a positive critical value of the anisotropy, below which the ground state is nonuniform. For the helicoid ribbon, the dispersion law for spin wave excitations about the tangential state is found to exhibit an asymmetry determined by the geometric and magnetic chiralities.

Original languageEnglish
Article number385401
JournalJournal of Physics A: Mathematical and Theoretical
Volume50
Issue number38
Early online date24 Jul 2017
DOIs
Publication statusPublished - 1 Sep 2017

Keywords

  • curved magnets
  • exchange energy
  • magnetic ribbon
  • nanoshell
  • nanowire

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    Gaididei, Y., Goussev, A., Kravchuk, V. P., Pylypovskyi, O. V., Robbins, J. M., Sheka, D. D., Slastikov, V., & Vasylkevych, S. (2017). Magnetization in narrow ribbons: Curvature effects. Journal of Physics A: Mathematical and Theoretical, 50(38), [385401]. https://doi.org/10.1088/1751-8121/aa8179