Correlations between low-field microwave absorption and magnetoimpedance in Co-based amorphous ribbons

Microwave power absorption measurements at 9.4 GHz were carried out on as-cast amorphous ribbons of nominal composition Co66Fe4B12Si13Nb4Cu. Two absorptions were observed: a small signal at a low dc field (<0.01T) and another one at a high dc field (∼0.1682T). The high-field signal shows all the features corresponding to ferromagnetic resonance. The low-field absorption (LFA) signal exhibits different characteristics such as hysteresis and a minimum in power absorption at zero magnetic field. A correlation between this LFA signal and magnetoimpedance measurements showed that both electromagnetic processes are associated with the same phenomenon.