Static and Dynamic Magnetization of Gradient FeNi Alloy Nanowire

FeNi binary nanowires with gradient composition are fabricated by the electrodeposition method. The energy dispersive spec-trometer line-sweep results show that the composition changes gradually along the wire axis. The gradient FeNi nanowires exhibit polycrystalline and crystal twinning at different areas along the nanowire axis, with a textured face-centered cubic structure. The static and dynamic magnetization properties are characterized by a hysteresis loop and ferromagnetic reso-nance with pumping frequencies from 12-40 GHz. The linear dispersion of the pumping frequency vs: the resonance field has been observed with the applied bias field higher than the saturation field, corresponding to the hysteresis loop. The field-sweep linewidths decrease with increasing pumping frequency, and the frequency-sweep linewidths stay nearly constant at the unsaturated region. The linewidth is a Gilbert type at the saturated state, with damping of 0.035 +/- 0.003. Compared with the damping of the homogeneous composition FeNi nanowire (a = 0.044 +/- 0.005), the gradient FeNi nanowire may have less eddy current damping, which could make it an alternative candidate for spintronics and microstrip antennas.