A Low-Cost Vibrating Sample Magnetometry Based on Audio Components

Measurement of magnetization is an important characterization step for magnetic materials to understand their fundamental properties and to utilize in industrial applications[1]. In this project, we construct a cheap and versatile vibration sample magnetometer (VSM) using the sound card. We tested our VSM for the hysteresis loops of three distinct magnetic samples: bulk Nickel piece, perm-alloy thin film with an easy- plane anisotropy, and Co/Pt multilayer with perpendicular magnetic anisotropy. The magnetizations of corresponding loops are analyzed at different frequencies and, the noises are also measured and compared for two methods. Although sound card performance is not very good for the frequencies below 20 Hz due to the cut-off frequency, its sensitivity is approximately 7 times better than that of lock-in amplifier at higher frequencies up to 60 Hz. The measured sensitivity of our sound card based VSM is of the order of emu, which is better than the sensitivities obtained in the previous similar experiments [2] at room temperature.

[1] S. Legl, et al. Vibrating coil magnetometer for milli-Kelvin temperatures, 81 (2010).
[2] D. Jordán, et al. Detection of magnetic moment in thin films with a home-made vibrating sample magnetometer, 456 (2018).