Langevin Simulation of Thermally Activated Magnetization Reversal in Nanoscale Pillars

Abstract

Numerical solutions of the Landau-Lifshitz-Gilbert micromagnetic model incorporating thermal fluctuations and dipole-dipole interactions (calculated by the Fast Multipole Method) are presented for systems composed of nanoscale iron pillars of dimension 9 nm x 9 nm x 150 nm. Hysteresis loops generated under sinusoidally varying fields are obtained, while the coercive field is estimated to be 1979 $\pm$ 14 Oe using linear field sweeps at T=0 K. Thermal effects are essential to the relaxation of magnetization trapped in a metastable orientation, such as happens after a rapid reversal of an external magnetic field less than the coercive value. The distribution of switching times is compared to a simple analytic theory that describes reversal with nucleation at the ends of the nanomagnets. Results are also presented for arrays of nanomagnets oriented perpendicular to a flat substrate. Even at a separation of 300 nm, where the field from neighboring pillars is only $\sim$ 1 Oe, the interactions have a significant effect on the switching of the magnets.

19 pages RevTeX, including 12 figures, clarified discussion of numerical techniques

Cited by in corpus (19)

• A method for atomistic spin dynamics simulations: implementation and examples
• Energy dissipation and switching delay in stress-induced switching of multiferroic devices in the presence of thermal fluctuations
• Binary switching in a symmetric potential landscape
• Statics and Fast Dynamics of Nanomagnets with Vortex Structure
• Switching of Dipole Coupled Multiferroic Nanomagnets in the Presence of Thermal Noise: Reliability of Nanomagnetic Logic
• Calculation of coercivity of magnetic nanostructures at finite temperatures
• Kinetic Monte Carlo Simulations of a Model for Heat-assisted Magnetization Reversal in Ultrathin Films
• Critical analysis and remedy of switching failures in straintronic logic using Bennett clocking in the presence of thermal fluctuations
• Magnetization Reversal in Elongated Fe Nanoparticles
• Binary information propagation in circular magnetic nanodot arrays using strain induced magnetic anisotropy
• Separating read and write units in multiferroic devices
• Area-Delay-Energy Tradeoffs of Strain-Mediated Multiferroic Devices
• The Transition State in Magnetization Reversal
• Reversal Modes of Simulated Iron Nanopillars in an Obliquely Oriented Field
• Interplay between Exchange Interaction and Magnetic Shape Anisotropy of ferromagnetic nanoparticles in a non-magnetic matrix for rare-earth-free permanent magnets
• Resolution-dependent mechanisms for bimodal switching-time distributions in simulated Fe nanopillars
• Projective Dynamics Analysis of Magnetization Reversal
• Reducing error rates in straintronic multiferroic dipole-coupled nanomagnetic logic by pulse shaping
• Two Modes of Magnetization Switching in a Simulated Iron Nanopillar in an Obliquely Oriented Field