Curie constant

In magnetism, the Curie constant is a material-dependent property that relates a material's magnetic susceptibility to its temperature through Curie's law.

The Curie constant, when expressed in SI units, has the unit kelvin (K), by
$C = \fracn g^2 J(J+1),$
where $n$ is the number of magnetic atoms (or molecules) per unit volume, $g$ is the Landé g-factor, $\mu_$ is the Bohr magneton, $J$ is the angular momentum quantum number and $k_$ is the Boltzmann constant. For a two-level system with magnetic moment $\mu$, the formula reduces to
$C = \fracn \mu_0 \mu^2,$
while the corresponding expressions in Gaussian units are
$C = \fracn g^2 J(J+1),$
$C = \fracn\mu^2.$

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

$M = \fracH.$

This equation was first derived by Pierre Curie.

Because of the relationship between magnetic susceptibility $\chi$, magnetization $\mathbf$ and applied magnetic field $\mathbf$ is almost linear at low fields, then

$\chi = \frac\approx\frac,$

this shows that for a paramagnetic system of non-interacting magnetic moments, magnetization $\mathbf$ is inversely related to temperature $T$.

See also

* Paramagnetism
* Curie–Weiss law

References

Thermodynamic properties
Physical constants
Pierre Curie

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