Magnetostatic dipolar domain-wall pinning in chains of permalloy triangular rings

Abstract

In a combined experimental and numerical study, we investigated the details of the motion and pinning of domain walls in isolated and interacting pennalloy triangular rings (side 2 /Lm, width 250 nm, and thickness 25 nm). To induce interaction between the rings, they were arranged either in vertical chains with an apex of each triangle in proximity to the edge center of the triangle above it or in horizontal chains where the proximity is between the adjacent corners of the triangles. Using longitudinal and diffraction magneto-optic Kerr effects, magnetic force microscopy, and micromagnetic simulations, we detennined the field dependence of the spin structure in the rings. In all cases the remnant state of each ring is an "onion" state characterized by two domain walls-one head to head the other tail to tail-pinned at the apexes. In isolated rings the magnetization reversal occurs between two onion states via the fonnation of an intennediate vortex state, which arises from the motion and annihilation of the two domain walls. In the case of the horizontal chains the reversal mechanism is unchanged except that the dipolar interaction affects the field range in which the rings are in the vortex state. In the case of vertical chains an additional intennediate state is observed during reversal. The new state involves a domain wall pinned at the center of the edge that is in close proximity to the apex of its neighbor, We show that the domain-wall motion in this last case can be modeled by a triple potential well. Because the new state requires that a domain wall be pinned at the neighboring apex, our observations can be viewed as a very elementary fonn of magnetic logic. PACS number(s): 75.60.Ch, 75.60.Jk, 78.20.Ls

Control of the chirality and polarity of magnetic vortices in triangular nanodots

“…17 All previously reported analyses on the switching of the polarity of the vortex core is devoted to the circular dots where the chirality is not visible by magnetic force microscopy ͑MFM͒ and cannot be controlled. Alternatively, it has been reported that in circular dots with truncated edges and other certainly complex engineered defects, [18][19][20][21][22][23][24][25] the nucleation point of the vortex could be controlled. This allows a possibility of additional control of vortex chirality.…”

Vortex State Suppression in a Hexagonal Array of Interacting Py Triangular Rings

“…Indeed, the downward peak observed in the rst branch of the loop in correspondence of the VS is turned to upward in the reverse branch due to the change of VS chirality. In the H conguration, the measured H 1, and H 2, values are smaller than those recorded for non-interacting MNs of ≈ 20 Oe and ≈ 80 Oe, respectively [3]. Beyond that, the sequence of states explored by the MNs during the reversal process is not aected by magnetostatic interactions.…”

“…In an earlier work, we studied the eects of dipolar interactions between two adjacent corners, viz. two DWs [3], and we found that interactions induced a change in switching elds values. In this paper, we investigate a dierent conguration, namely the rings are ordered in a hexagonal pattern (see Fig.…”

“…When triangular rings are considered, during magnetization reversal their magnetic conguration goes through the so called vortex state (VS) and onion state (OS) [3]. In the former, the MN displays a continuous magnetization prole producing a weak stray eld (WSF) close to each corner, thus the ring has three magnetically equivalent WSF corners.…”

Comparative study of the ferromagnetic resonance behavior of coupled rectangular and circular Ni80Fe20rings

“…To date, there are many reports on the static behavior of magnetic rings including circular [8][9][10], elliptical [11], triangular [12,13], square [14,15], rhombic [16], rounded rectangular [17,18], and rectangular rings [19]. The effect of ring dimensions [20][21][22], shapes [19,23], inter-ring spacing [24,25], configurational anisotropy [11,26,27], and engineered defects [28,29] on static reversal of the rings have also been examined. In contrast, reports on dynamic behavior of ring elements have focused on the investigation of circular ring [30][31][32][33] and limited work on other ring shapes such as rounded rectangular [34] and triangular rings [35].…”