Vibrating sample magnetometer is a good tool to investigate materials’ magnetic properties.
Sitting in an electromagnet as shown in the above Figure, the sample to be measure is magnetized by external magnetic field and vibrating at ± 1 mm about 88 Hz. The vibration varies the magnetic flux through the pickup coil and induces a voltage signal. This induced voltage signal depends on several factors: (1) coil turns, orientation, and geometry; (2) sample vibration frequency and amplitude; (3) sample’s magnetic moment. Magnetic moment is a function of magnetic field and temperature. By fixing either field or temperature, M vs H (or T) can be obtained. One M-H example is shown in the following Figure a (magnetization hysteresis). Reference
It is worthy to mention that a related term B, magnetic induction, is defined as
B-H is different from M-H, based on the definition (Figure b), and it is can be measured by different methods.