Magnetization Reversal by Rotation

Abstract

The mechanism of magnetization reversal by simple rotation has been discussed by a number of authors, but a completely general analysis (applicable to a single-domain ferromagnetic body of any type of anisotropy, with an applied field in an arbitrary direction) has not been given. The purpose of this paper is to present such an analysis. General differential equations are derived which can be used to describe the rotation process in any body for which demagnetization and anisotropy factors can be written. These equations are then applied to a sphere, a cylinder, and a thin sheet. Both uniaxial and cubic anisotropy are considered for the sphere and cylinder; only uniaxial anisotropy (the kind observed in deposited films) is considered for the thin sheet. The resulting differential equations can be solved numerically to obtain output voltages, switching times, and switching constants.

Using hysteresis behaviour to determine the anisotropy and interactions in complex self-assembled Co metallic nanoparticle systems

“…The effective field used in the equation is the vector sum of the applied, anisotropy and interaction fields [6]. a denotes the damping constant, g is the gyromagnetic factor andM is the magnitude of the magnetisation.…”

Bifurcation in precessional switching

“…Considerable effort has been dedicated to solving this equation numerically in potentially technologically relevant situations. [5][6][7][8] Yet, one important element seems to have remained undetected, both experimentally and numerically: there are solutions of Eq. ͑1͒ which show the phenomenon of bifurcation.…”

Analytical determination of the LLG zero-damping critical switching field

“…Solutions to ( 5 ) in terms of the spherical coordinates of m [5] were computed numerically by He, Doyle, and Fujiwara [l] for several values of At, < 10 ns, and several values of a. They determined that the non-equilibrium trajectories of m allowed magnetization reversal by coherent rotation to occur at smaller applied field magnitudes than predicted by Stoner-Wohlfarth analysis.…”