Magnetism and magnetoresistance of single Ni–Cu alloy nanowires

Abstract

Arrays of magnetic Ni–Cu alloy nanowires with different compositions were prepared by a template-replication technique using electrochemical deposition into polycarbonate nanoporous membranes. Photolithography was employed for obtaining interdigitated metallic electrode systems of Ti/Au onto SiO2/Si substrates and subsequent electron beam lithography was used for contacting single nanowires in order to investigate their galvano-magnetic properties. The results of the magnetoresistance measurements made on single Ni–Cu alloy nanowires of different compositions have been reported and discussed in detail. A direct methodology for transforming the magnetoresistance data into the corresponding magnetic hysteresis loops was proposed, opening new possibilities for an easy magnetic investigation of single magnetic nanowires in the peculiar cases of Stoner–Wohlfarth-like magnetization reversal mechanisms. The magnetic parameters of single Ni–Cu nanowires of different Ni content have been estimated and discussed by the interpretation of the as derived magnetic hysteresis loops via micromagnetic modeling. It has been theoretically proven that the proposed methodology can be applied over a large range of nanowire diameters if the measurement geometry is suitably chosen.

Magnetotransport Mechanism of Individual Nanostructures via Direct Magnetoresistance Measurement in situ SEM

“…The MR value reaches a maximum value of 1.14% at about ±270 Oe and a minimum value at the saturation field, indicating a 270 Oe coercivity. This value is smaller than that of reported CoCu/Cu MNW arrays, which is deduced that the single MNW escapes the neighbored magnetic interactions that exist in MNW arrays from group measurements. Besides, the aforementioned off-axis EH experimental result and micromagnetic simulations reveal that the shape anisotropy plays a decisive role in the distribution of magnetic moments in the CoCu/Cu MNW, which also means that the MR of individual MNWs is dominated by anisotropic magnetoresistance (AMR).…”

Tuning structural and magnetic properties of Fe oxide nanoparticles by specific hydrogenation treatments

“…Such specific behaviors of remanence provide evidence for its direct relation to the unidirectional anisotropy induced at the interface of the two distinct magnetic phases in the core–shell structure of oxide NPs. On the other hand, the much higher remanence of metallic Fe NPs in sample A300C has to be related only to the long range magnetic order inside the unidimensional chain-like organization of NPs, initially oriented along the saturation field 34 , 35 .

Figure 6 Temperature dependence of the remanent magnetization in the absence ( a ) and in the presence of field cooling ( b ).

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Relationship between the Formation of Magnetic Clusters and Hexagonal Phase of Gold Matrix in AuxFe1−x Nanophase Thin Films

“…Here, possible in plane magnetic anisotropy axes could be highlighted by following the hysteresis loops (Kerr angle versus the magnetic field) collected at different orientations of the applied field with respect to a direction in the sample plane. The idea behind such experiments is that the shape of the hysteresis loop is strongly related to the direction of the field with respect to a possible magnetic easy axis of the system, as theoretically and experimentally proven in [ 31 , 32 , 33 ]. Accordingly, if the field is oriented along an easy axis (EA) of magnetization, the hysteresis loop will have a quasi-rectangular shape with a jump at a switching field, whereas in the perpendicular direction, the Kerr angle (proportional to the film magnetization) will have a linear variation, reaching the saturation above a saturation field.…”