Magnetic Switching of a Stoner-Wohlfarth Particle Subjected to a Perpendicular Bias Field

摘要

Characterized by uniaxial magnetic anisotropy, the Stoner-Wohlfarth particle experiences a change in magnetization leading to a switch in behavior when tuned by an externally applied field, which relates to the perpendicular bias component ( h perp ) that remains substantially small in comparison with the constant switching field ( h 0 ). The dynamics of the magnetic moment that governs the magnetic switching is studied numerically by solving the Landau-Lifshitz-Gilbert (LLG) equation using the Mathematica code without any physical approximations; the results are compared with the switching time obtained from the analytic method that intricately treats the non-trivial bias field as a perturbation. A good agreement regarding the magnetic switching time ( t s ) between the numerical calculation and the analytic results is found over a wide initial angle range (0.01 θ 0 0.3), as h 0 and h perp are 1.5 × K and 0.02 × K , where K represents the anisotropy constant. However, the quality of the analytic approximation starts to deteriorate slightly in contrast to the numerical approach when computing t s in terms of the field that satisfies h perp 0.15 × K and h 0 = 1.5 × K . Additionally, existence of a comparably small perpendicular bias field ( h perp h 0 ) causes t s to decrease in a roughly exponential manner when h perp increases.