Abstract
Abstract In the present investigation, systematic method to fabricate nanowire arrays with a linear gradient of cobalt-iron composition has been reported. The nanowires were fabricated by direct current (DC) electro-deposition following a multi-step titration method into a commercial anodic aluminium oxide (AAO) template. Nearly 100% gradient of Co and Fe content in the nanowires is achieved following the present method. The gradient of Co and Fe composition along the nanowires is established by Energy-dispersive X-ray (EDX) mapping in scanning electron microscope (SEM). The results from EDX mapping are further supported by the microstructural characterization along the wire axis using high resolution transmission electron microscope (HRTEM) images and SAED pattern. The microstructural characterization reveals variation of crystalline phases that are signature of Co and Fe content along the wires. To explore the magnetization dynamics of nanowire arrays, ferromagnetic resonance (FMR) study was performed in flip-chip geometry. The FMR study shows the presence of four well-separated resonance peaks in gradient nanowires which is a unique finding in the present investigation. A detailed FMR analysis has been presented to reveal the origin of these peaks. The values of the Gilbert damping parameter, obtained from the FMR linewidth analysis establish the correlation of FMR response with the average composition of Co–Fe in nanowires, grown in each step of titration. This study highlights the necessity of the detailed investigation of microstructures and magnetization dynamics of gradient ferromagnetic nanowire arrays that are emerging in high-frequency spintronics applications, more suitable for a tunable tri-band band-pass filter.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
