In that position, What can we observe in following parameters. (i) coercivity (Hc), (ii) Remanences (Mr), (iii) magnetic saturation moment (Ms).
Whether Hc and Mr values are decreased or all the three are decreased. Can any one explain the magnetism.
Hc and Mr decreased while Ms increased for details check the study of Magnetite SPIONs Nanoparticles .................
Hc and Mr decreased while Ms increased for details check the study of Magnetite SPIONs Nanoparticles .................
It is difficult to think how a given material can go from ferro or ferrimagnetic behavior to a superparamagnetic (SPM) one, except for a change in the actual temperature of the sample.
To have a SPM behavior you need single-domain particles (i.e., particles with sizes below 40-100 nm depending on the material composition). Depending on the size of the single-domain particles, and the magnetic anisotropy of the material, you will have a blocked bahavior at room temperature (that is, a ferromagnetic loop with coercivity and remanence) OR the unblocked state which is the superparamagnetic behavior.
Hope this helps.
How do you actually control the changes in the material that you claim to be minor? Many aspects may play a role, and some could depend sensitively on composition or process parameters during specimen preparation. It comes down to speculating when no information is being given with respect to these aspects.
In dilute magnetic semiconductors (your topics included above hint at this being the class of systems you're referring to) superparamagnetic dopant clusters may form as an extrinsic phase to the ferromagnetic one in GaMnAs, see e.g. our work in the link below.
If whatever changes your composition slightly also favored formation of such clusters, then there could be some reason for your observation. I'm wildly speculating here, though.
http://www.sciencedirect.com/science/article/pii/S0368204805000745
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