Magnetic Reversal in Nanoscopic Ferromagnetic Rings

Abstract

We present a theory of magnetization reversal due to thermal fluctuations in thin submicron-scale rings composed of soft magnetic materials. The magnetization in such geometries is more stable against reversal than that in thin needles and other geometries, where sharp ends or edges can initiate nucleation of a reversed state. The 2D ring geometry also allows us to evaluate the effects of nonlocal magnetostatic forces. We find a `phase transition', which should be experimentally observable, between an Arrhenius and a non-Arrhenius activation regime as magnetic field is varied in a ring of fixed size.

arXiv commentRevTeX, 23 pages, 7 figures, to appear in Phys. Rev. B

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• Asymptotic Exit Location Distributions in the Stochastic Exit Problem
• Regularisation of functional determinants using boundary perturbations
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• Theory of metastability in simple metal nanowires
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• Large Fluctuations, Classical Activation, Quantum Tunneling, and Phase Transitions
• Annular Spin-Transfer Memory Element
• Micromagnetic Simulations of Ferromagnetic Rings
• Thermal Activation Barriers for Creation and Annihilation of Magnetic Droplet Solitons in the Presence of Spin Transfer Torque
• The Escape Problem in a Classical Field Theory With Two Coupled Fields
• The Order of Phase Transitions in Barrier Crossing
• Polymerization in magnetic metamaterials
• Noisy Classical Field Theories with Two Coupled Fields: Dependence of Escape Rates on Relative Field Stiffnesses