Hi Anil,

Magnetic susceptibility (χ) is defined as the ratio between the magnetization of the material (M) and the applied magnetic field strength (H), χ = M/H. When magnetization is not a linear function, you use the differential susceptibility χ = dM/dH. Because M v H is not a linear function, the value of the derivative and thus χ will change as you vary H.

I suspect what you mean to extrapolate from this plot is the Curie constant, using the relationship Curie Law (χ = C/T). This relationship only holds for paramagnetic samples though, which your material is not if there is a remnant magnetization.

I hope this helps.

Plot dM/dH curve w.r.t to H and you will get the Chi value variation.

Ans as Jeff said earlier it is constant for paramagnetic or diamagnetic samples where you will get the straight line for M Vs H curve.

Thanks Jeff, My material, Fe3O4, is reported ferrimagnetic in literature. Since I synthesised it in laboratory, a conformation of the magnetic behaviour is needed by measuring magnetic susceptibility. This value is found by measuring χ = M/H, as you mentioned, but at very low magnetic fields. The value is obtained when we start with applying zero magnetic field and gradually increase its magnitude. In my case the machine started from maximum -ve value. I was searching if there is an alternative method or model to find chi.

I have no intentions to find curie constant.

Thanks Vinay, Your method gives two dM/dH values for same H. Which one to consider. Also see my reply to Jeff's answer. That might help to understand my problem. My material is reported ferrimagnetic.