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On which factors do the magnetic susceptibility of these type of materials depend? Id assume ferromagnets in general have higher susceptibility than ferrimagnets but is this true in all cases?

For those who are interested:

Ferromagnetism The magnetic moments in a ferromagnet have the tendency to become aligned parallel to each other under the influence of a magnetic field. However, unlike the moments in a paramagnet, these moments will then remain parallel when a magnetic field is not applied

Antiferromagnetism Adjacent magnetic moments from the magnetic ions tend to align anti-parallel to each other without an applied field. In the simplest case, adjacent magnetic moments are equal in magnitude and opposite therefore there is no overall magnetisation.

Ferrimagnetism similar to antiferromagnetism but the aligned magnetic moments (always anti-parallel as far as i'm aware) are not of the same size; that is to say there is more than one type of magnetic ion in two or more different sublattices. An overall magnetisation is produced but not all the magnetic moments may give a positive contribution to the overall magnetisation.

descriptions taken from http://www.doitpoms.ac.uk/tlplib/ferromagnetic/printall.php then editted slightly for clarifaction of ferrimagnetism

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  • $\begingroup$ Perhaps a more detailed or refined question title and question? For instance, could you give a brief clarification of the definition of each? For instance, I know about ferromagnetic materials, but do not know much about ferrimagnetic materials. $\endgroup$
    – honeste_vivere
    Commented Jan 5, 2015 at 18:22
  • $\begingroup$ The distinctive feature of all these three types of magnetism is that the magnetisation remains even where there is no externally imposed field - they are permanent magnets. For ferro and ferri, this can be measured by the remanence. The susceptibility is of course still important, but not the key issue. $\endgroup$
    – akrasia
    Commented Jan 5, 2015 at 19:08
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    $\begingroup$ The question asks if a measure of susceptibility could be used to differentiate between a ferro and ferri magnet $\endgroup$
    – Goods
    Commented Jan 5, 2015 at 19:23
  • $\begingroup$ The difference between ferro and ferrimagnetism is obviously local, so I don't see how an average measure would allow to differentiate materials... $\endgroup$
    – TZDZ
    Commented Jan 6, 2015 at 8:41

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From the comments below the original question, I'll give a try to answer the question "Is there a way to distinguish between ferromagnetic and ferrimagnetic materials based on their magnetic susceptibility?"

At page 194 of Cullity & Graham's book "Introduction to magnetic materials", one can see a plot of $1/\chi(T)$ for ferri and ferro magnetic materials. It turns out that above the Curie point, $1/\chi(T)$ of ferromagnetic materials is as a straight line (which can be understood thanks to the Curie-Weiss law). However, it is not quite the same case for ferrimagnetic materials. Instead, $1/\chi(T)$ is curved right above $T_C$ and then becomes as a straight line for higher temperatures (it's in fact a hyperbola, which is different from the straight line of ferromagnets).

There's also a difference in $1/\chi(T)$ below $T_C$, the curvature is greater for ferromagnetic materials than it is for ferrimagnetic materials.

Thus, with a careful examination of $1/\chi(T)$, one should, in principle, be able to determine whether the material is ferromagnetic or ferrimagnetic.

Now onto your question about the parameters on which $\chi$ depends. For ferrimagnetic materials, $\chi$ depends on many parameters, some of them aren't found in the expression for $\chi$ of ferromagnetic materials. Examples are $\gamma_{aa}$, $\gamma_{bb}$ and $\gamma_{ab}$ which are molecular field coefficients. The details can be found in the above book and other sources like "The Néel Theory of Ferrimagnetism" by J. Samuel Smart.

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