Transverse and vortex domain wall structure in magnetic nanowires with uniaxial in-plane anisotropy

Abstract

Micromagnetic and analytical models are used to investigate how in-plane uniaxial anisotropy affects transverse and vortex domain walls in nanowires where shape anisotropy dominates. The effect of the uniaxial anisotropy can be interpreted as a modification of the effective wire dimensions. When the anisotropy axis is aligned with the wire axis (θ a = 0), the wall width is narrower than when no anisotropy is present. Conversely, the wall width increases when the anisotropy axis is perpendicular to the wire axis (θ a =π/2). The anisotropy also affects the nanowire dimensions at which transverse walls become unstable. This phase boundary shifts to larger widths or thicknesses when θ a = 0, but smaller widths or thicknesses when θ a = π/2.2

Development of TEM Holder Generating In-Plane Magnetic Field Used for <i>In-Situ</i> TEM Observation

“…8(b)), the area of a domain around the pad's center increased and invaded into the wire. As a result, a vortex type DW 38) where the local moment formed a closed loop was injected as indicated by the arrowhead. Note that the edge contrast of the wire alternated between the left and right parts of the wire.…”

Investigating the effect of a stress-based uniaxial anisotropy on the magnetic behaviour of La0.7Sr0.3MnO3elements

“…It has recently been shown that the addition of a uniaxial anisotropy contribution in permalloy nanowires can either increase or decrease the domain wall width [13]. Walker breakdown effects can also be suppressed and a 30% increase in domain wall velocity was reported in a similar system when the in-plane anisotropy was oriented perpendicular to the wire long axis [14].…”

“…In effect, this removes the demagnetizing field from the ends of the wire. Given that the magnetization profile differs substantially with the addition of a uniaxial anisotropy, and differs significantly from a transverse to vortex structure, we define the domain wall width to be the region enclosed by M x /M s = ±0.95, thus allowing a direct comparison of domain wall widths, which is independent of wall structure [13]. Without a uniaxial anisotropy, the width of a transverse domain wall, ΔTW, was measured to be 125 nm, and the width of a vortex domain wall, ΔVW, was measured to be 258 nm in a LSMO nanowire.…”

“…However, with a uniaxial anisotropy term, the width of the transverse domain wall, ΔTW, is reduced by 45% to 69 nm and the vortex domain wall width, ΔVW, is reduced by 30% to 182 nm, respectively. Essentially, the uniaxial anisotropy acts with the shape anisotropy to alter the effective wire dimensions [13].…”

Vortex dynamics in Co-Fe-B magnetic tunnel junctions in presence of defects

“…In particular, the vortex dynamics has received a growing interest, since it can be described as a rigid magnetic configuration by a single parameter. 4 It is important in nanowires, being energetically more stable than the transverse wall for large wire cross-sections (vortex wall), 5 as well as in disks. In vortex domain walls, core switches can occur at material defects, 6 while in nano-disks the magnetic vortex configuration was employed to probe single defects.…”