# Is the effective magnetic moment defined for substances that follow the Curie-Weiss law?

The effective magnetic moment is defined as follows: $$$$\mu_{eff} = \left(\chi_M \frac{3kT}{N_A\mu_0\mu_B^2}\right)^{\frac{1}{2}}$$$$ where $$\chi_M$$ is the molar magnetic susceptibility, $$k$$ is the Boltzmann constant, $$N_A$$ is the Avogadro number, $$\mu_0$$ the magnetic permeability and $$\mu_B$$ the Bohr magneton.

My question is whether this quantity is defined also for ferromagnetic and antiferromagnetic substances above the critical temperature, or if on the contrary is only valid for "pure" paramagnets. Can then be linked to the number of unpaired electrons?