Preparation and magnetic properties of gradient diameter FeCoNi alloys nanowires arrays

Highlights: • FeCoNi MNWs are successfully prepared by AAO template-assisted electrochemical deposition method. • The effects of gradient diameter on magnetic properties of GDNWs were compared to UDNWs by FORCs curves. • There was a SD state with enhanced magnetostatic interactions in GDNWs. • The magnetic interaction, magnetic domain states and reversibility of GDNWs are different from those of UDNWs. FeCoNi MNWs with uniform and gradient diameter are successfully prepared by three-electrode constant potential deposition in AAO template. The deposition time of FeCoNi MNWs overgrow in the AAO template are investigated. The morphology and structure of FeCoNi MNWs are characterized by TEM, EDS, SAED and XRD. The effects of magnetization reversal mechanism, magnetic interaction, magnetic domain states and reversibility of FeCoNi MNWs are studied by FORCs technology. The results show that the magnetization reversal mechanism of UDNWs-20 present coherent mode, while UDNWs-60 and UDNWs-100 present curling mode as well as coherent mode. There is a transition of curling inverse to coherent inverse in magnetic reversal of GDNWs-20~100. When the UDNWs diameter increase from 20 nm to 60 nm and 100 nm, the domain state change from SD to MD state and the irreversible component reduce from about 100% to 71.3% and 60.2%. The SD GDNWs-20~100 contains 72.8% irreversible and 27.2% reversible components. The magnetic interaction, magnetic domain states and reversibility of FeCoNi GDNWs are different from those of UDNWs.