An electrostatic automatic torque magnetometer for measuring the properties of magnetic thin films

A simple automatic torque magnetometer is described in which the specimen torque is balanced by an electrostatic torque developed in a quadrant electrometer arrangement. The high servo-loop gain of the system allows the specimen position to be held stationary to within 0.5 mrad. The restoring voltage applied to the quadrants is recorded on a punched tape for computer analysis and as a series of printed numerical data: it may also be continuously monitored on a pen recorder. A complete torque curve of a magnetic thin film may be examined in a period of 5 minutes. The minimum torque resolvable by the instrument is about 10 -4 dyn cm.