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 where is the number of magnetic atoms (or molecules) per unit volume, is the Landé g-factor, is the Bohr magneton, is the angular momentum quantum number and is the Boltzmann constant. For a two-level system with magnetic moment , the formula reduces to while the corresponding expressions in Gaussian units are The constant is used in Curie's law, which states that for a fixed value of an applied magnetic field , the magnetization of a material is (approximately) inversely proportional to temperature. This equation was first derived by Pierre Curie. Because of the relationship between magnetic susceptibility , magnetization and applied magnetic field is almost linear at low fields, then this shows that for a paramagnetic system of non-interacting magnetic moments, magnetization is inversely related to temperature . See also Paramagnetism Curie–Weiss law References Thermodynamic properties Physical constants Pierre Curie