Magnetic properties of cylindrical diameter modulated Ni80Fe20 nanowires: interaction and coercive fields

Abstract

Magnetic properties of cylindrical Ni80Fe20 nanowires with modulated diameters are investigated theoretically as a function of their geometrical parameters and compared with those produced inside the pores of anodic alumina membranes by pulsed electrodeposition. We observe that the Ni80Fe20 nanowires with modulated diameters reverse their magnetization via the nucleation and propagation of a vortex domain wall. The system begins generating vortex domains in the nanowire ends and in the transition region between the two segments to minimize magnetostatic energy generated by surfaces perpendicular to the initial magnetization of the sample. Besides, we observed an increase of the coercivity for the sample with equal volumes in relation to the sample with equal lengths. Finally, the interaction field is stronger in the case of constant volume segments. These structures could be used to control the motions of magnetic domain walls. In this way, these nanowires with modulated diameters can be an alternative to store information or even perform logic functions.

Ni-Co Alloy and Multisegmented Ni/Co Nanowire Arrays Modulated in Composition: Structural Characterization and Magnetic Properties

“…The small tilting of the loops that is more evident for the Co NWs (larger saturation magnetization), is attributed to the inter-nanowire magnetostatic interactions [49][50][51][52] and explains the lower value of mr for Co NWs. In contrast, in the perpendicular configuration one detects narrow hysteresis loops with small HC and remanence magnetization, as theoretically expected [48].…”

Quantitative magnetometry analysis and structural characterization of multisegmented cobalt–nickel nanowires

“…For instance, highly hexagonally ordered cylindrical magnetic nanowires (NWs) have been easily prepared by their electrochemical deposition into the nanopores of anodic aluminum oxide (AAO) membranes, displaying multiple technological applications including ultrahigh-density magnetic recording media [8], sensors and optoelectronic devices [17].…”

“…Recently, most of the fundamental and applied research focused on magnetic materials have been directed towards the understanding and application of the astonishing magnetic properties found in nanostructures, which are quite different from those observed in the bulk systems and exhibit unique size and shape dependences. For these reasons, the nanoscale materials with designed features, such as barcode-like structures, are excellent candidates for a large variety of technological applications [4][5][6][7][8]. In this matter, a need of specialized characterization techniques to measure the magnetic behavior of individual nanostructures is required [9][10][11][12].…”

Template Assisted Deposition of Ferromagnetic Nanostructures: from Antidot Thin Films to Multisegmented Nanowires

“…Furthermore, advanced deposition techniques suitable for conformal coating of 3D structured substrates, such as atomic layer deposition (ALD), allow for additional control of the morphological parameters of AAO membranes, enabling independent control of pores diameter, while keeping constant the interpore distances [11]. In addition, advanced anodization protocols, including hard anodization [12,13], pulsed or sequential anodization [14], or lithography-guided anodization [15] allowed recently to obtain ideally ordered nanoporous templates, exhibiting also pore diameter * corresponding author; e-mail: vmpp@uniovi.es modulations [16,17]. The spatial and periodic pores arrangement of the AAO templates, together with the confined growth of the magnetic material at the nanoscale deposited in the nanoporous alumina template, translate into the appearing of cooperative phenomena in the nanostructured materials, which in turn lead to tailor novel functional properties that differ from that of 3D bulk and 2D thin film systems [18,19].…”