Characterization of Magnetostrictive Film on Shaft Surface in Inverse Magnetostrictive Torque Sensor Using Magneto-Optical Kerr Effect

Methods for evaluating the characteristics of magnetostrictive materials include dynamic magnetic domain observation using a magneto-optical Kerr effect microscope, obtaining B-H curves using a vibrating sample type magnetometer that vibrates a magnetized sample with a DC magnetic field, and so on. Generally, magnetic domains are observed in magnetic materials on flat surfaces. The authors previously researched and developed an inverse magnetostrictive torque sensor in which a magnetostrictive material is deposited on a cylindrical shaft surface. Therefore, to accurately evaluate the characteristics of a torque sensor, it is necessary to observe the magnetic domains while torque is applied on a curved surface. This paper explains that method and presents the results of dynamic domain observation of magnetostrictive materials on the shaft surface using a newly developed magneto-optical Kerr effect microscope.