Automatic Torque Balance for Magnetic Anisotropy Measurements

This is the authors' abstract. We don't add key points for this paper.

An automatic torque balance for the determination of magnetic anisotropy in ferromagnetic single crystals is described. The balance consists of a mechanical coupling between a solenoid suspended in a static magnetic field and a single crystal specimen. The torque produced by the specimen causes a minute motion of the solenoid, which is detected by means of a light beam-mirror-phototube network, and an automatically controlled current is fed back to the solenoid, establishing a torque equal and opposite to that produced. A voltage proportional to the feedback current, and thus the applied torque, is recorded on one axis of an X-Y recorder. The other axis is driven by a voltage governed by the direction of magnetic field in which the crystal is suspended. A method that automatically compensates for the deviation of magnetization from applied field direction in highly anisotropic crystals is described, and further advantages of the automatic balance over other systems are discussed.