Magnetoimpedance measurements of ferromagnetic resonance and antiresonance

We report the observation of both ferromagnetic resonance and antiresonance in a magnetic metal using a magnetoimpedance technique. In this experiment , the magnetoimpedance was measured as the frequency was swept from 30 MHz to 11 GHz at constant magnetic fields ranging up to 1.1 kOe (88 kA/m). The sample was an amorphous NiCo-rich soft-magnetic wire with a saturation magn etization sufficiently small to meet both the resonance and antiresonance c onditions at frequencies below 10 GHz. A saturation magnetization, very clo se to that obtained through magnetometry, was deduced using a simultaneous fit to the field dependence of the resonance and antiresonance frequencies. This experiment clearly demonstrates that magnetoimpedance provides a powe rful tool for characterizing the intrinsic properties of magnetic metals, w ith several advantages compared to standard ferromagnetic resonance techniq ues. (C) 2000 American Institute of Physics. [S0003-6951(00)04043-2].