Correlations among magnetic, electrical and magneto-transport properties of NiFe nanohole arrays

Abstract

In this work, we use anodic aluminum oxide (AAO) templates to build NiFe magnetic nanohole arrays. We perform a thorough study of their magnetic, electrical and magneto-transport properties (including the resistance R(T), and magnetoresistance MR(T)), enabling us to infer the nanohole film morphology, and the evolution from granular to continuous film with increasing thickness. In fact, different physical behaviors were observed to occur in the thickness range of the study (2 nm < t < 100 nm). For t < 10 nm, an insulator-to-metallic crossover was visible in R(T), pointing to a granular film morphology, and thus being consistent with the presence of electron tunneling mechanisms in the magnetoresistance. Then, for 10 nm < t < 50 nm a metallic R(T) allied with a larger anisotropic magnetoresistance suggests the onset of morphological percolation of the granular film. Finally, for t > 50 nm, a metallic R(T) and only anisotropic magnetoresistance behavior were obtained, characteristic of a continuous thin film. Therefore, by combining simple low-cost bottom-up (templates) and top-down (sputtering deposition) techniques, we are able to obtain customized magnetic nanostructures with well-controlled physical properties, showing nanohole diameters smaller than 35 nm.

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

“…For the same film thickness, the rougher the surface the larger is the coercivity [23]. Consequently, by increasing the film thickness, H c rises due to the surface roughness and grain size increase, which results in an increase of the magnetic shape anisotropy for these thin films [24][25][26]. This observation agrees well with our experimental data, as shown in Fig.…”

NiFe/(Ni,Fe)3S2 Core/Shell Nanowire Arrays as Outstanding Catalysts for Electrolytic Water Splitting at High Current Densities

“…As illustrated in Figure , NiFe alloy nanowire arrays are fabricated using AAO as the template. The unentangled nanowires provide large reaction surface areas, guided paths for charge transport, interwire channels for fast mass transfer of electrolyte, and enhanced release of gas bubbles . Further surface sulfurization of the NiFe nanowires through a simple ion exchange process generates the NiFe/(NiFe) 3 S 2 core/shell nanowire arrays (termed S‐NiFe NWAs).…”

Ordered La0.7Sr0.3MnO3nanohole arrays fabricated on a nanoporous alumina template by pulsed laser ablation

“…In this context, the synthesis and design of nanoscale structures have attracted much attention due not only to their potential applications but also for their size dependent physical properties. Continuous films with nanosized voids, called nanohole arrays, are one example of such interesting nanostructured materials which exhibit enhanced exchange bias, modified magnetization reversal, increased coercivity and the unusual domain wall pinning effect [5][6][7]. Such nanoholes generate magnetic charges in their vicinity and create stray field that promotes local magnetization reversal by magnetization rotation.…”