Vibrating Sample Magnetometer (VSM):

• A schematic drawing of the VSM sample holder and detection mechanism of VSM is shown in Figure 30.01. The set up was invented by Simon Foner at MIT in 1955.

Figure 30.01: Schematic of sample holder and VSM mechanism.

• A sample to be studied is placed inside the uniform magnetic field and then vibrated sinusoidally using vibrator made of linear actuators or modified audio speakers.

• The induced voltage in the pickup coil is proportional to the sample's magnetic moment, but does not depend on the strength of the applied magnetic field.

• In a typical setup, the induced voltage is measured through the lock-in amplifier using the piezoelectric signal as its reference signal. Lock-in principle of measurement allows the measurement of signal weaker than the noise. By measuring in the field of an external electromagnet, it is possible to obtain the hysteresis curve of a material.

• VSM measures the magnetization of a small sample of magnetic material placed in an external magnetizing field by converting the dipole field of the sample into an AC electrical signal.