Representative examples are shown in Figure 5. In particular, the segment highlighted with number (1) on the left of Figure 5 has a composition of Co83Ni17, which was determined by EDS operating

the microscope in TEM mode. The spots of the corresponding SAED pattern can be indexed to the [0001] zone axis of a Co-Ni single crystal with hcp structure. In addition, it is observed that the <10-10 > direction lies along the nanowire axis. On the other hand, the segment highlighted with number (2) having Co52Ni48 composition exhibits a SAED pattern that can be indexed to the [−321] zone VRT752271 order axis of a Co-Ni alloy with fcc structure, where the <111 > direction lies along the nanowire axis. Interestingly, in several of these SAED patterns, the diffraction spots appear slightly elongated, or well, two or three spots appear very close. This fact evidences a texture that could be originated by fluctuations in the distribution of the Co/Ni ratio into the same segment and/or the effect of transversal stresses produced by the confined growth into the pores of the alumina template. The appearance of the hcp structure for Co-Ni alloys with high Co MK5108 ic50 content is in agreement with

its equilibrium phase diagram [26]. However, it is worth noting that in some of the studied nanowire segments, the concentration fluctuations and structural differences have also https://www.selleckchem.com/products/sotrastaurin-aeb071.html (-)-p-Bromotetramisole Oxalate appeared, probably as a consequence of the non-equilibrium nature of the electrodeposition processes. The RT hysteresis loops depicted in Figure 6 show small coercive field values of H C = 150 and 194 Oe for the parallel and perpendicular directions, respectively. The reduced remanence (m r = M r / M S) in both directions takes similar values close to 0.04. These results point out that the array of multisegmented Co-Ni nanowires

does not clearly show an easy magnetization axis, indicating that the longitudinal magnetic shape anisotropy of the multisegmented nanowire arrays is strongly competing against the magnetocrystalline anisotropy induced by the presence of hcp crystals with their easy axis lying in the perpendicular direction with respect to the long axis of the nanowires. Furthermore, dipolar interactions among adjacent barcode nanowires having narrow segments with different compositions and crystalline structures can have a strong effect in the resulting hysteresis loops, smearing the characteristic features of the abovementioned anisotropies. Figure 6 Room temperature hysteresis loops of multisegmented Co 54 Ni 46 /Co 85 Ni 15 nanowires. Measured in the parallel and perpendicular directions with respect to the nanowire long axis. The inset shows an enlargement in the low-field region.