As you can see, the extrapolation of the curve 1 / X gives a negative asymptotic temperature of the order of -50 K. The absolute value of this temperature corresponds (approximately) to Néel's temperature. So your material is bein AF with a Néel temperature of the order of 50K.

Moreover, the behavior in 1 / T observed at low temperature (T

Dear

Dr. Mohamed EI Hafidi

Thank you for your quick and kind response. I have plotted dX/dT and found 46K. Would you kindly explain what are the reason for other two peaks?

I am afraid I do not know how to subtract paramagnetic component. Please help me to learn it.

For more quantitative investigations, we first must know: -the stoichiometric composition of the material - its cristallographic structure -if the sample is powder, crystal, single crystal, etc?. - impurities that may remain in the sample... Knowing the free radicals in the sample and their magnetic

state (spin), we can assimilate them to paramagnetic

moments and model their susceptibility using the Curie law:

Xpar = C / T, C = mu0 (N/V) (1/3kB)(peff)2

peff =mB sqrt(S(S+1))

mu0= 4pi 10-7 (in the MKSA system) Then, by subtracting this paramagnetic term, one could

investigate the remaining antiferromagnetic contribution and refine it to better localize the temperature of Néel and explain the other peaks (other transitions, multiphase system, ...?)

erratum peff = mB g sqrt(S(S+1)) , g =Landé Factor (g= around 2)