On the pinning of domain walls in low magnetization materials

Abstract

The proposal of an interaction potential between 180° Bloch walls and nonmagnetic obstacles, precipitates or pores, is presented. Use is made of the analogy between this phenomenon and the pinning of grain boundaries in polycrystalline materials. The model takes into account the increase of energy due to the flexibility of the boundary and it is applicable to low magnetization materials. Using this approach it is possible to calculate the coercive force and to compare it with early findings. The numerical values obtained are in agreement with the values we find in the literature with the advantage that the proposed potential is expressed in a simple analytical form.

Dynamic Coercivity of Advanced Ferritic Steel during Long-Term Isothermal Ageing

“…Physically, the magnetization process is closely related to domain wall movement, and the coercivity strongly depends on the degree of pinning of domain wall. 12,13) Microstructural impurities, such as inclusion, dislocation and grain boundary may hinder the domain wall movement in ferromagnetic materials, which are potentials of pinning sites of domain wall. A dislocation, which is a typical lattice defect evolving local strain due to an atomic mismatch with the matrix, imparts a force on the domain wall, and thus, could be an effective obstacle to domain wall movement.…”

Dynamic Coercivity of Tempered Ferritic Steel Subjected to Creep-Fatigue for Nondestructive Evaluation by Reversible Permeability

“…The energy per area of the wall boundary is associated with each pinning center. The coercive field is as the following equation [15].…”

“…The coercivity linearly increases with the reciprocal of the square root of grain size as well as theoretical calculation [13,14]. Wörner et al assumed that coercivity is due to the pinning of Bloch walls by second-phase particles considering that the wall are rigid walls [15]. Fidler et al investigated that the dislocation should be the Bloch wall pinning site in a similar manner to the mechanical problem of dislocation bowing of the pinning center [16].…”