Dear Srishty,

I did not understood well which "relaxation" you are refering... If is magnetic relaxation of magnetization, the simpliest way to get some information about the dynamics of magnetic relaxation using a VSM may be done if measurements at low temperature range are available (e.g. temperatures from 4 to 300 K). In such case you may create a command routine in order the VSM switch the applied field quickly from 0 to a small value (e.g. ~100 Oe), then perform a serie of magnetization measurements as a function of time at the 100 Oe field then turn off the field and repeat the serie of magnetization measurements as function of time at 0 Oe field. This procedure should be repeated for several different temperatures in the considered range, for example, 4K, 10K, 15K, 20K, 25K, 30K,... The time interval you need to wait while measuring the magnetization at 0 and at 100 Oe should be sufficient long in order to allow a good identification of the resulting curves of magnetization as functions of time. Such curves are expected to be exponentials: M(t) = Mo exp (- t / tau) when the field is turned off and M(t) = Mo ( 1 - exp (- t / tau) ) when the field is turned on. The values of tau obtained from such curves vary with the temperature and, in general, they follow the Arrhenius law such like this:

tau = tauzero * exp ( delta / k T ) where delta is the relaxation energy barrier, k is the Boltzmann constant and T is the measuring temperature... The whole process expends a lot of time! So, be sure whether the informations obtained by this method are really useful for your research...

The same informations you may obtain much more quickly from measurements of AC magnetic susceptibility (if you have an AC susceptometer) performed as function of temperature in different frequencies. In this case, the relaxation times "tau" are directly obtained as the inverse of measuring frequency and the values of T considered in the Arrhenius equation are obtained from the peak of the imaginary part of AC susceptibility. Take a look in this short paper of my authorship (available here in RG) where I used such kind of procedures:

Physica B, 384 (2006) 300-302

ok thank you Walter.