Micromagnetics of the dynamic susceptibility for coupled Permalloy stripes

Abstract

The dynamic susceptibility of arrays of narrow Permalloy stripes (9 mm × several μm × 200 nm) has been investigated using a single-coil broadband susceptibility spectrometer. Disagreement is observed between experimental results and the macroscopic Landau-Lifshitz model. This model does not take into account the dipolar interaction between magnetic stripes. We have performed micromagnetic calculations that include these dipolar interactions, and have found the resulting frequency dependence of the dynamic susceptibility in the linear regime to be in good agreement with our experimental data.

Spin dynamics in exchange-biased F/AF bilayers

“…Before annealing (as grown), there is no magnetic interaction between the NiFe and the MnNi layer. The permeability spectra are typical of damping by spin rotation processes in a NiFe layer [8]. For the annealed samples, when the exchange and the anisotropy fields increase, the level of the real part of the permeability µ ′ (0) at low frequency decreases and the roll off frequency increases.…”

Micromagnetic Investigation of Microwave Permeability of Magnetic Artificial Spin Ice

“…The micromagnetic simulations are performed using a three-dimensional object-oriented micromagnetic framework (OOMMF) by solving the Landau-Lifshitz-Gilbert (LLG) equation as a function of time [5]. The microwave permeability spectra are obtained following the field-pulse processes [6]- [9]. The stable ground state of the magnetizations was firstly obtained by minimizing the total energy.…”

Hysteretic resonance frequencies and magnetization reversal in exchange biased polycrystalline F/AF bilayers

“…1. This spectrum is characterized by the uniform mode of resonance of a NiFe single layer with the characteristics of spin rotation damping processes: the resonance frequency of m 00 at about 700 MHz and the low frequency m 0 of about 2200 [27]. In order to achieve an antiferromagnetic tetragonal (FCT) state, a high temperature annealing was performed.…”