Magnetic modes in Ni nanowires

Abstract Spin-wave modes in Ni nanowires electrodeposited in alumina are investigated by model calculations and magnetic resonance experiments. Since the wires are very thin, the main magnetization variation at low temperatures is parallel to the wires. The corresponding modes—probed by the magnetic resonance and responsible for the spontaneous magnetization of the wires—are generally localized. A spin-wave analysis of the magnetization yields a low-temperature contribution linear in T and proportional to the Bloch-wall width. The large broadening of the resonance lines, above 0.1 T for fields parallel to the wires is explained by the real-structure distribution of sharp localized resonance modes.