Harmonic detection of multipole moments and absolute calibration in a simple, low-cost vibrating sample magnetometer

The design and fabrication of a low-cost, highly sensitive, fully automated vibrating sample magnetometer for dc magnetization measurements is described. Harmonic detection of magnetic multipole moments is demonstrated experimentally in an inhomogeneously magnetized nickel sample at room temperature and in a gadolinium sample across the magnetic phase transition. A method is presented to nullify the earth’s effective field even without any shielding. More significant, the setup uses only one lock-in amplifier for signal detection, vibration excitation, and temperature measurement and control. First principles calculations give an absolute determination of the instrumental conversion factor that agrees with the experimental calibration factor. The setup is stable from 77 to 300 K, the overall sensitivity is ⩽5×10−6 emu, and the reproducibility is ⩽1%.