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 magnetization sufficiently small to meet both the resonance and antiresonance conditions at frequencies below 10 GHz. A saturation magnetization, very close 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 powerful tool for characterizing the intrinsic properties of magnetic metals, with several advantages compared to standard ferromagnetic resonance techniques. (C) 2000 American Institute of Physics. [S0003-6951(00)04043-2].