Magnetic Domain of Stepped Magneto-Impedance Sensor Controlled by a Normal Magnetic Field

Abstract

A thin-film magneto-impedance (MI) sensor has the unique property of a step-like magneto-impedance change, in the case where the sensor has an in-plane uniaxial inclined easy axis. A domain observation shows that the step-like change is due to a magnetization transition within three states, including the longitudinal single domain with parallel state, that with anti-parallel state and the inclined Landau-Lifshitz domain (ILLD). In a condition where the sensor has an easy axis of 70º relative to the short-side axis of the rectangular element, the transition is limited between the parallel and anti-parallel states despite the existence of a stable ILLD. Previous work showed that the application of a normal field could produce the ILLD state. This paper reports a control method for the magnetic domain by controlling the normal field. It is shown that the existence of a distributed canted angle relative to the normal direction in the normal field enhances the reconstruction of the ILLD domain state.