Periodic magnetic domains in single-crystalline cobalt filament arrays

Abstract

Magnetic structures with controlled domain wall pattern may be applied as potential building blocks for three-dimensional magnetic memory and logic devices. Using a unique electrochemical self-assembly method, we achieve regular single-crystalline cobalt filament arrays with specific geometric profile and crystallographic orientation, and the magnetic domain configuration can be conveniently tailored. We report for the first time the transition of periodic anti-parallel magnetic domains to a compressed vortex magnetic domains depending on the ratio of height vs. width of the wires. A "phase diagram" is obtained to describe the dependence of the type of magnetic domains and the geometrical profiles of the wires. Magnetoresistance of the filaments demonstrates that the contribution of series of 180 o domain walls is over 0.15% of the zero-field resistance ρ(H = 0). These self-assembled magnetic nanofilaments, with controlled periodic domain patterns, offer an interesting platform to explore domain-wall-based memory and logic devices.

Magnetic structure and internal field nuclear magnetic resonance of cobalt nanowires

“…4c). This is a manifestation of the hcp c -axis being perpendicular to the nanowires, 56,57 as suggested by the XRD diffraction patterns of Fig. 3.…”

“…On the other hand, a strong crystalline anisotropy (like hcp Co) perpendicular to the wire axis will be in competition with the shape anisotropy, possibly leading to a magnetic easy axis perpendicular to the wires. 56,57,67,68 The case of the Co nanowires with a relatively narrow diameter of 50 nm grown in presence or absence of additives in a PC membrane was the most straightforward as it was dominated in both case by shape anisotropy. In this instance, the dipolar field acting on a wire due to its neighbors can safely be neglected because of the large interwire distances.…”

Magnetic Nanowires and Nanotubes

“…These have been reported for, e.g., CoNi alloys (Bran et al 2017a; Fig. 13a), single-crystalline hcp Co (Vila et al 2009, Ivanov et al 2013b, Chen et al 2016, single-crystal CVD Ni wire (Kan et al 2018b). Magnetic anisotropy may also come from strain, for wires embedded in a solid matrix.…”

3D Nanomagnetism in Low Density Interconnected Nanowire Networks

“…[7][8] Networks of interconnected magnetic nanowires could provide an exciting platform to explore 3-dimensional (3D) nanomagnetism, where their structure, topology and frustration may be used as additional degrees of freedom to tailor the materials properties. [9][10][11][12] For example, cylindrical nanowire building blocks present opportunities for exploring curvature-driven Dzyaloshinskii-Moriya interaction (DMI), 13 exotic types of 3D topological spin textures 9,[14][15][16] and chiral symmetry breaking; [17][18][19] such networks could be model systems to study 3D "racetrack" memories, [20][21] where the information is encoded in DWs propagating along the nanowires, and the intersections may be used to manipulate DWs, such as pinning, annihilation or changing their topological character.…”

“…Porous metallic nanostructures have exciting potential applications in such areas as lightweight materials, , energy conversion and storage, − and filters. , Networks of interconnected magnetic nanowires could provide an exciting platform to explore 3-dimensional (3D) nanomagnetism, where their structure, topology, and frustration may be used as additional degrees of freedom to tailor the materials properties. − For example, cylindrical nanowire building blocks present opportunities for exploring curvature-driven Dzyaloshinskii–Moriya interaction (DMI), exotic types of 3D topological spin textures ,− and chiral symmetry breaking; − such networks could be model systems to study 3D “racetrack” memories, , where the information is encoded in domain walls (DWs) propagating along the nanowires, and the intersections may be used to manipulate DWs, such as pinning, annihilation or changing their topological character. Recent studies have shown the possibility of addressing DWs in a contactless fashion via chemisorption, which is attractive for 3D systems.…”