Design and development of a first order reversal curve measurement enabled variable temperature vibrating sample magnetometer

In this paper we present the design, construction and calibration of a sensitive vibrating sample magnetometer (VSM) and temperature variable setup with a capability to measure magnetization of magnetic materials from 100 K to 400 K with First Order Reversal Curve (FORC) measurement facility. It uses a bipolar power supply to energize an electromagnet capable of attaining ±1 Tesla field, subwoofer speaker for vibrating the sample and the induced voltage in four coil setup is measured by a lock-in amplifier. All hardware is controlled by a customized LabView program. The cryostat is designed such that the temperature can be varied continuously from 100 K to 400 K using liquid nitrogen up to room temperature and forced nitrogen gas/air for high temperatures study. We report here the VSM sensitivity of up to 10 −2 emu/gm and can measure much weaker signals. The FORC protocol in this system is implemented via a dedicated virtual instrument in LabView capable of magnetic field reversal and termination at appropriate point to study domain nucleation field. The detailed analysis of the data is done using the open-source resources. We present the FORC measurement for Co 0.5 Zn 0.5 Fe 2 O 4 , a ferrimagnet. To establish the sensitivity of the instrument we present the results of magnetization measurement with temperature and phase transition study of La 0.4 Ca 0.6 MnO 3 and La 0.75 Sr 0.25 MnO 3 .