Vibrating Sample Magnetometers, as the name implies,
vibrate the sample as part of the measurement process. This
the Fluxmeter element of the system with the dynamic component it
requires to make the measurement. The applied field is changed so
each measurement point the field is static and hence no eddy currents
to cause problems.
VSM’s typically use a lock-in amplifier as part of the
magnetism detection process that provides the capability of generating
highly sensitive measurements and subsequently is very useful for
extremely small samples i.e. thin-films etc.
The applied field is often generated using iron-pole
pieces and a field solenoid that limits the field to approximately 2.4
Tesla. While this is fine for some materials it presents a
limitation on the VSM.
The alternative is to use super conducting coils.
is where a field generation coil is surrounded by liquid nitrogen, or
even liquid helium to reduce resistance and provide cooling. This
allows high fields to be generated but at the expense of a high initial
cost and high running costs with very long measurement times (see table
VSM’s use an open circuit form of magnetic measurement
and must account for self-demagnetisation effects.
They are excellent for use with very small samples but
as the magnets get larger the mass of the sample proves problematic, as
this must be vibrated.