A review on magneto-impedance effect in amorphous magnetic materials

Recently the magneto-impedance (MI) effect in soft magnetic amorphous wires and ribbons has attracted wide interest both for its application as sensitive magnetic field and current sensors and for studying from a physical point of view. This phenomenon is mainly observed in a series of Co and Fe-based amorphous magnetic wires and ribbons and change in MI as high as 360% have been observed. After suitable heat treatment, sensitivity can be further improved. This behaviour is related to the magnetic domain structure and magnetisation dynamics of the materials. The MI effect has potential applications in super sensitive sensors, high speed computer peripherals, micromagnetics, information apparatus, mechatronics, automobile, industrial robots, power electronics, medical electronics and industrial process control. In this paper we have reviewed the current state of research on this phenomena, particularly, the alloy preparation, measurement system and various annealing techniques used in the MI effect enhancement.