How this calculator works
This is the SI volume convention chi = C/T, so C is in kelvins. For independent moments, C = mu0 n mu_eff²/(3kB). A cubic cell of edge a containing N effective magnetic sites has number density N/a³. The moment input is the effective moment in Bohr magnetons, including angular-momentum factors, rather than a single projection. Fractional site counts can represent partial occupancy. Molar and cgs Curie constants have different units and factors. The model omits magnetic interactions, saturation and ordering.
Formula
C = mu0 N(mu_eff muB)²/(3 kB a³); n = N/a³; chi = C/T. Here mu_eff is the number of Bohr magnetons and a is converted from nm to m.
Worked example
For one magnetic site in a 1 nm cubic cell and effective moment 1 Bohr magneton, C is about 0.002609399 K. Two sites each with moment 2 Bohr magnetons increase C by a factor of eight.
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Frequently asked questions
Is this a molar Curie constant?
No. This is the SI volume constant in K. A molar constant includes molar volume and has units m3 K/mol.
Why does the moment appear squared?
The weak-field thermal response depends on the mean squared dipole moment.
Can this predict a Curie temperature?
No. The constant in the paramagnetic susceptibility law is different from a magnetic ordering temperature.