# Magnetic Nanowires
## 3 Results
### Interplay between the Magnetic and Magneto-Transport Properties in Interconnected Nanowire Networks  
In this section, we report on magneto-transport measurements performed on homogeneous CNW networks (40 nm diameter) made from CoNi alloys, while sweeping the magnetic field in the out-of-plane (OOP) and in-plane (IP) directions. In this system, the magnetic anisotropy has been found to be dependent on the alloying composition. The experimental setup for magneto-transport shown in Figure 12a is based on a two-probe system created at the surface of the filled template by local removing of the cathode by plasma etching. In this configuration, the current is directly injected to the branched CNW structure from unetched sections of the metallic cathode and goes through the network thanks to the high degree of electrical connectivity of the CNWs. Figure 12b,c show resistance curves measured at 290 K with the external field applied in the OOP and IP directions for interconnected NiCo CNW networks. As observed in Figure 12b, the maximum resistance in the Ni-rich Ni\({}_{75}\)Co\({}_{25}\) sample is reached near zero applied field for both directions, which is consistent with remanent magnetization states where the magnetization tends to be aligned along the nanowire axis, due to shape anisotropy. Conversely, the decrease of the resistance near zero field in the Co-rich Ni\({}_{32}\)Co\({}_{68}\) sample (see Figure 12c) is consistent with the decrease of the remanent magnetization as a result of the misalignment of the magnetization with respect to the NWs axis. Indeed, decreasing the Ni content below 45% leads to the appearance of a transverse hcp magnetocrystalline anisotropy contribution, which competes with the magnetostatic anisotropy contribution, since the c-axis is perpendicular to the nanowires axis, as revealed by XRD analysis [61; 62]. Therefore, the magnetic anisotropy in OOP of Ni-rich networks is higher than that of Co-rich ones, as expected. Figure 12d shows the MC field \(H_{\text{MC}}\) as a function of the Ni content (x), obtained by FMR measurements on several Ni\({}_{x}\)Co\({}_{1\text{-x}}\) CNW networks. As expected, \(H_{\text{MC}}\) is negative and increases toward the observed limiting value for pure Co networks with perpendicular c-axis as the Ni content is reduced. It is worth mentioning that the small negative anisotropy contribution observed for the Ni sample could be originated by residual stresses due to the reduced diameter of the nanowires, as recently suggested [87]. Figure 12e shows the anisotropic magnetoresi  
Figure 12: **(a)** schematic representation of an electrode design for electrical measurement of CNW network embedded in 3D porous PC membrane; (**b**,c)** magnetoresistance curves for **(b)** Ni\({}_{75}\)Co\({}_{25}\) and **(c)** Ni\({}_{32}\)Co\({}_{68}\) CNW networks measured at room temperature by applying the external field in the OOP (continuous lines) and IP (dashed lines) directions; **(d)** variation of the magnetocrystalline anisotropy field \(H_{\text{MC}}\) with respect to the Ni content (x) for the Ni\({}_{x}\)Co\({}_{1\text{-x}}\) CNW networks; **(e)** variation of the AMR ratio with respect to the alloy composition at \(T=20\) K, 150 K, and 290 K.  
content (x) at \(T=20\), 150 and 290 K for the different Ni\({}_{\text{x}}\)Co\({}_{\text{1-x}}\) CNW networks (See [61; 62] for more details on the estimation of AMR ratio in such CNWs). The observed variation of the AMR ratio as a function of x is consistent with previous reports on electrodeposited films and metallurgically processed NiCo alloys [88; 89; 90], where the maximum at x \(\sim 75\%\) for both temperature values is attributed to a magnetostriction and MC constants close to zero and to a saturation magnetization of about one Bohr magneton per atom for that particular alloy composition [90].