Vortex head-to-head domain walls and their formation in onion-state ring elements

Abstract

Magnetization configuration of vortex head-to-head ͑HTH͒ domain walls and the wall-formation process in Ni 80 Fe 20 ring elements were investigated using magnetic force microscopy ͑MFM͒ and micromagnetic simulation. At remanence, two types of vortex HTH domain walls were observed to be stable in the onion configuration, depending on the film thickness: single-and double-vortex HTH domain walls for 40 and 65 nm thick ring elements, respectively. As the vortex core nucleated during formation of the HTH domain wall, exchange energy began to decrease, accompanied by an increase in the width of the wall. Vortex nucleation in the 65 nm thick ring was found to be much faster than in the 40 nm thick ring element. This effect can be attributed to the higher initial magnetostatic energy density in the thicker ring.

Field-dependent evolution of magnetic states in Co ring arrays

“…In the literature, different magnetic states during the reversal processes in rings such as ''onion'' state, and flux-closure ''vortex'' states, as well as metastable ''twisted'' states have been identified [15][16][17][18][19]. The evolutions among the different magnetic states are associated with nucleation, annihilation, and propagation of domain walls.…”

Transport dynamics of superparamagnetic microbeads trapped by mobile magnetic domain walls

“…In such structures, the DW velocity can be precisely clocked with a rotating field. Prior to experiments, a large in-plane magnetic field was applied to coerce the tracks into an "onion" domain configuration, with two circumferential magnetic domains separated by DWs lying along the field axis 34,[37][38][39][40] . A dilute suspension of SPM beads was then placed in a polydimethylsiloxane (PDMS) well on the wafer surface and sealed with a microscope cover slip.…”

Broadband ferromagnetic resonance spectroscopy of permalloy triangular nanorings

“…2 Fundamentally, mesoscopic ferromagnetic rings have been shown to display a range of magnetic configurations, including onion, vortex, and twisted states. [3][4][5][6] While the static magnetic properties of ring of different shapes, such as circular, 7 square, 8 and triangular rings 9 have been extensively studied, studies of the dynamic ones have been limited to only circular [10][11][12][13][14][15][16][17] and rectangular rings. 18 The spin dynamics in triangular shaped nanorings (TNR) is of particular interest because of the special symmetrical shape anisotropy and the possibility of preferential pinning of domain walls at the sharp corners.…”