Vibrating sample magnetometer with a step motor

Abstract

A new version of the low-frequency (3.6 Hz) vibrating sample magnetometer was built. Its mechanical part consists of a crank transducer with a step motor driven by a microcontroller. Step durations are programmed in such a way that the signal from pick-up coils is perfectly sinusoidal as a function of time. The signal is narrow-band amplified, digitized at each of 400 steps of one period and lock-in detected by a computer. The magnetometer has low noise and may be used not only with superconducting but with water-cooled magnets.