Curie constant

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The Curie constant is a material-dependent property that relates a material's magnetic susceptibility to its temperature.

The Curie constant, when expressed in SI units, is given by

C = \frac{\mu_0 \mu_B^2}{3 k_B}N g^2 J(J+1)[1]

where N is the number of magnetic atoms (or molecules) per unit volume, g is the Landé g-factor, \mu_B (9.27400915e-24 J/T or A·m2) is the Bohr magneton, J is the angular momentum quantum number and k_B is Boltzmann's constant. For a two-level system with magnetic moment \mu, the formula reduces to

C = \frac{1}{k_B}N \mu_0 \mu^2

The constant is used in Curie's Law, which states that for a fixed value of a magnetic field, the magnetization of a material is (approximately) inversely proportional to temperature.

\mathbf{M} = \frac{C}{T}\mathbf{B}

This equation was first derived by Pierre Curie.

Because of the relationship between magnetic susceptibility \chi, magnetization \scriptstyle\mathbf{M} and applied magnetic field \scriptstyle\mathbf{H}:

\chi = \frac{\mathbf{M}}{\mathbf{H}}

this shows that for a paramagnetic system of non-interacting magnetic moments, magnetization \scriptstyle\mathbf{M} is inversely related to temperature T (see Curie's Law).

See also[edit]


  1. ^ Kittel, Charles. Introduction to Solid State Physics, 8th Edition. Wiley. p. 304. ISBN 0-471-41526-X.