Magnetization reversal and nonexponential relaxation via instabilities of internal spin waves in nanomagnets

Abstract

A magnetic particle with atomic spins ordered in an unstable direction is an example of a false vacuum that decays via excitation of internal spin waves. Coupled evolution of the particle's magnetization (or the vacuum state) and spin waves, considered in the time-dependent vacuum frame, leads to a peculiar relaxation that is very fast at the beginning but slows down to a nonexponential long tail at the end. The two main scenarios are linear and exponential spin-wave instabilities. For the former, the longitudinal and transverse relaxation rates have been obtained analytically. Numerical simulations show that the particle's magnetization strongly decreases in the middle of reversal and then recovers.

6 EPL pages, 4 figures

References in corpus (5)

• Fokker-Planck and Landau-Lifshitz-Bloch Equations for Classical Ferromagnets
• Finite size and temperature effects in the AF Heisenberg model
• Thermal fluctuations and longitudinal relaxation of single-domain magnetic particles at elevated temperatures
• Spin-wave theory for finite classical magnets and superparamagnetic relation
• Microscopic mechanisms of magnetization reversal

Cited by in corpus (6)

• Optimal switching of a nanomagnet assisted by microwaves
• Spin-Wave-Assisted Thermal Reversal of Epitaxial Perpendicular Magnetic Nanodots
• Magnetization reversal via internal spin waves in magnetic nanoparticles
• Are superparamagnetic spins classical?
• Simulation of a spin-wave instability from atomistic spin dynamics
• Surface-induced reduction of the switching field in nanomagnets