Kerr Effect as Method of Investigation of Magnetization Reversal in Amorphous Wires

Abstract

Magneto-optical Kerr effect has been employed for the investigation of the magnetization reversal process in Co-rich amorphous wires. The Kerr effect experiments have been performed in a new configuration with circular magnetic field produced by an electric current flowing through the studied wire. Changes of the Kerr effect hysteresis loops after annealing have been found to be related with the magnetic domain structure modification. This modification is attributed to the change of sign of magnetostriction constant.Optical effects, which demonstrate the influence of magnetization on the state of light are known as magneto-optical effects. Two main magneto-optical phenomena are usually distinguished, the Faraday effect and the Kerr effect. The Faraday effect is characterized by the rotation of the polarization plane and the change of the ellipticity when linearly polarized light passes through the magnetized medium. The Kerr effect [1] consists of the rotation of the plane of polarization and the change of the intensity of polarized light reflected from a surface of the magnetized matter. There are three magneto-optical Kerr effects depending on the mutual arrangement of the magnetization and the plane of incidence of the scattered light -polar, longitudinal and transverse. Experimental investigations have shown that the rotation of the polarization or the change of light intensity (depending on the magneto-optical effect configuration) is proportional to the projection of magnetization on one of the three orthogonal axes [2,3]. Based on this relation Kerr effects have been used to get the images of magnetic domains or to obtain magnetization loops.Usually the Kerr effect has been applied to study samples with plane surface. Recently, we have used the Kerr effect to investigate wire-shaped specimens. It is remarkable to note that the study of the magnetic properties of amorphous wires is a topic of great interest because of their outstanding properties, such as single and large Barkhausen jump or giant magneto-impedance effect [4,5]. It is known that the domain structure of the amorphous wire consists of an axially magnetized inner core and the outer shell, in which "maze" or "bamboo" structure can be observed [6]. Taking into account that the giant magneto-impedance effect is mainly a "surface" effect, the investigation of magnetic structure in the outer shell becomes a special meaning. So far, the Kerr

Nucleation and transformation of circular magnetic‐domain structure in amorphous microwires

“…The special peculiarity of the microwires is the nonplanar surface. For the MOKE magnetometry experiments 10 this peculiarity presents some disadvantages: the light reflected from the cylindrical surface of the microwire forms the conic surface (Fig. 1c).…”

Magneto-Optical Study of the Surface Reversal Process in Amorphous Glass-Coated Microwires With Positive Magnetostriction

“…4). The light reflected from the cylinder forms a conical surface [16], [17]. As a result, the incidence planes of all rays are not parallel, with opposite rotations on both sides forming the shape of letter "V" relative to main axis of microwire (Fig.…”

Surface magnetization reversal and magnetic domain structure in amorphous microwires

“…A specific feature here is a nonplanar surface of microwire. The light reflected from a cylindrical surface of the microwire forms a conic surface 7. The main idea of the MOKE experiments is MOKE without en external magnetic field: the studies have been performed in the presence of a circular magnetic field that was produced by electric current flowing along the microwire 7.…”

“…The present review is devoted to the recent results on magneto‐optical Kerr‐effect (MOKE) 6–9 investigation of the surface magnetization reversal and surface domain structure. We also discuss the relation between the surface magnetization reversal and GMI effect.…”