Single crystalline cylindrical nanowires – toward dense 3D arrays of magnetic vortices

Abstract

Magnetic vortex-based media have recently been proposed for several applications of nanotechnology; however, because lithography is typically used for their preparation, their low-cost, large-scale fabrication is a challenge. One solution may be to use arrays of densely packed cobalt nanowires that have been efficiently fabricated by electrodeposition. In this work, we present this type of nanoscale magnetic structures that can hold multiple stable magnetic vortex domains at remanence with different chiralities. The stable vortex state is observed in arrays of monocrystalline cobalt nanowires with diameters as small as 45 nm and lengths longer than 200 nm with vanishing magnetic cross talk between closely packed neighboring wires in the array. Lorentz microscopy, electron holography and magnetic force microscopy, supported by micromagnetic simulations, show that the structure of the vortex state can be adjusted by varying the aspect ratio of the nanowires. The data we present here introduce a route toward the concept of 3-dimensional vortex-based magnetic memories.

Multiscale differential phase contrast analysis with a unitary detector

“…For the Co segment we observed the concentration of the magnetization at the core of the NW which can be attributed to the complex 3D vortex structure due to the strong magnetocrystalline anisotropy of hcp Co [34,35]. In this case Eq.C.1 gives only a rough approximation, since it does not take into account strong magnetic stray fields going outside the Co segment (reaching up to 10% of the field inside).…”

“…As was recently demonstrated [35] hcp Co nanowires can represent a 3D vortex state. To probe the magnetic states of the ordered array of the Co/Ni nanowires we prepared a plane section of the aluminum oxide template with nanowires embedded inside of it (details see in [35]).…”

“…To probe the magnetic states of the ordered array of the Co/Ni nanowires we prepared a plane section of the aluminum oxide template with nanowires embedded inside of it (details see in [35]). With the field of Derived according to Table 1 the components of the magnetic field of the nanowires array are shown in Fig.…”

Two-photon lithography for 3D magnetic nanostructure fabrication

“…A common approach to fabricate 3D magnetic nanostructures is to electrodeposit a magnetic material into alumina templates or ion-track-etched templates. This is a promising route because electrodeposition is a well-established method for growing a range of magnetic materials [6] and has allowed the fabrication and characterization of cylindrical magnetic nanowires [3,7]. More recently, ion-track-etched templates have also been used to fabricate interconnected networks of NiCo nanowires [8].…”

Electron states in a sinusoidally deformed cylindrical quantum wire

“…Recent advances in nanotechnology have made it possible to fabricate nanowires of different sizes and geometries [1][2][3][4]. Nanowires have a variety of novel properties, rendering them invaluable in diverse disciplines like medicine [5], optoelectronics [6] and energy physics [7], among others.…”