Magnetization Reversal Process and Magnetostatic Interactions in Fe56Co44/SiO2/Fe3O4 Core/Shell Ferromagnetic Nanowires with Non-Magnetic Interlayer

Abstract

Nowadays, numerous works regarding nanowires or nanotubes are being published, studying different combinations of materials or geometries with single or multiple layers. However, works, where both nanotube and nanowires are forming complex structures, are scarcer due to the underlying difficulties that their fabrication and characterization entail. Among the specific applications for these nanostructures that can be used in sensing or high-density magnetic data storage devices, there are the fields of photonics or spintronics. To achieve further improvements in these research fields, a complete understanding of the magnetic properties exhibited by these nanostructures is needed, including their magnetization reversal processes and control of the magnetic domain walls. In order to gain a deeper insight into this topic, complex systems are being fabricated by altering their dimensions or composition. In this work, a successful process flow for the additive fabrication of core/shell nanowires arrays is developed. The core/shell nanostructures fabricated here consist of a magnetic nanowire nucleus (Fe56Co44), grown by electrodeposition and coated by a non-magnetic SiO2 layer coaxially surrounded by a magnetic Fe3O4 nanotubular coating both fabricated by means of the Atomic Layer Deposition (ALD) technique. Moreover, the magnetization reversal processes of these coaxial nanostructures and the magnetostatic interactions between the two magnetic components are investigated by means of standard magnetometry and First Order Reversal Curve methodology. From this study, a two-step magnetization reversal of the core/shell bimagnetic nanostructure is inferred, which is also corroborated by the hysteresis loops of individual core/shell nanostructures measured by Kerr effect-based magnetometer.

Magnetic Properties of GaAs/NiFe Coaxial Core-Shell Structures

“…The properties of such structures, including those of nanowires and nanotubes, are strongly dependent on their dimensions, shape anisotropy, and selected material. Nanotubes provide advantages over nanowires, due to possibilities to vary the thickness of the tube wall in addition to the control of the length and diameter [6][7][8][9]. Even wider possibilities to control the magnetic properties are ensured by coaxial core-shell structures.…”

“…Fe nanowires were deposited by ACD into alumina templates [26]. FeCo/Fe 3 O 4 core/shell nanowires were produced by a combination of PM electroplating and ALD in alumina templates [7].…”

Electrodeposition as a Tool for Nanostructuring Magnetic Materials

“…Then, the pores can be filled with a metal by electrodeposition, obtaining a core-shell metal-oxide structure. These strategies allow the synthesis of ferromagnetic/antiferromagnetic structures showing exhange-bias [121] or radial ferromagnetic layers separated by a non-magnetic layer controlling the magnetic coupling [119,125], introducing an additional degree of freedom into the control of the magnetic properties of electrodeposited nanowires.…”

Electrodeposition and magnetic properties of Co x Dy1−x nanotube arrays

“…ne-dimensional magnetic nanomaterials, such as the magnetic nanotube, nanowire and arrays of nanotubes or nanowires, have attracted much more attention recently due to their distinctive properties and tremendous application potential [1][2][3][4][5] in a high-density perpendicular magnetic memory device, [6][7][8] magnetic sensor, 9,10) electroacoustic device, 11) damping device 12) and spintronic devices. 13,14) Owing to its unique wire-like shape, one-dimensional nanostructures of transition metals and alloys exhibit higher saturation magnetization and coercivity than their bulk counterpart.…”