Influence of current amplitude on asymmetric off-diagonal magnetoimpedance in field-annealed amorphous ribbons

The off-diagonal magnetoimpedance in field-annealed Co-based amorphous ribbons was measured using a pick-up coil wound around the sample. The influence of the current amplitude on the first and second harmonics in the pick-up coil voltage was studied. The second harmonic contribution to the voltage increases with the current amplitude, and at sufficiently high current amplitudes, the amplitude of the second harmonic becomes higher than that of the first harmonic. The asymmetric two-peak behavior of the field dependences of the harmonic amplitudes was observed, which is related to the coupling between amorphous bulk and surface crystalline layers appearing after annealing. The experimental results are interpreted in terms of a quasi-static rotational model.