Simulation of magnetization reversal processes in finite ferromagnets with defects

Stable states of magnetic inhomogeneities localized in the region of defects

“…The minimization condition of energy (1) can be represented in the form (2) For definiteness, the dependences of the material parameters of the sample on the coordinate y are taken in the form (3) which corresponds to a defect in the form of a lamellar magnetic inclusion [6,11,16]. Here, L is the width of the defect; M s is the saturation magnetization; and A 1 , A 2 , K u1 , K u2 , M s1 , and M s2 are the specified constants of the material.…”

“…Therefore, below, it is sufficient to consider the values of these functions in the region y > 0. In this case, the functions θ i (y) should satisfy the conditions (6) and the matching conditions that follows from expres sions (3):…”

“…Obviously, among these factors can be the inclusion of demagnetizing fields induced by surface charges due to the finiteness of the sample, because they have a significant effect on the stability of 0° DWs [6,18]. At the same time, a specific feature of the structure of 0° DWs (II) is that, in the magnetiza tion distribution, there is a region (π/2 < θ < 3π/2) in which the projections of the magnetic moments on the OZ axis are opposite to the magnetization direction in the bulk of the sample (|y| > L/2).…”

“…Investigation of the dependences of these characteristics on the presence of defects in a sample is a very difficult and, at the same time, actual problem that has technical applications. However, despite certain theoretical developments in this field [3][4][5][6] and the significant progress made in computer simulation of such problems [2,[7][8][9][10], the mechanisms governing such dependences are still not sufficiently understood. In this series of studies, men tion should be made of the work [11], in which the authors considered some aspects of the nucleation conditions and structural features of magnetic inho mogeneities formed at defects.…”

Numerical simulation of the generation of multisoliton type magnetic inhomogeneities in ferromagnets with inhomogeneous parameters

“…It is also known that, in these systems, apart from conventional linear excitations, namely, spin waves, there are nonlinear excitations, such as, for example, breathers [11]. The magnetic inhomogeneities generated on defects are frequently described as the 0° domain walls (or magnetic soliton) [3,12]. It should be noted that, in a defect-free magnet, magnetic inhomogeneities of 0° domain wall type are energetically unfavorable as compared to the homogeneous state of the magnetization vector.…”