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 Hysteresis loops generated under sinusoidally varying fields are obtained, while the coercive field is estimated to be using linear field sweeps at 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 the interactions have a significant effect on the switching of the magnets.
- Received 31 January 2001
DOI:https://doi.org/10.1103/PhysRevB.64.134422
©2001 American Physical Society