Curie–Weiss law (magnetism)

The Curie–Weiss law describes how a paramagnet’s magnetic susceptibility varies inversely with temperature above its Curie–Weiss temperature. It extends the Curie law by accounting for interactions between magnetic moments.

Magnetic susceptibility: A measure of how strongly a material becomes magnetized in response to an applied magnetic field. The law specifies susceptibility’s temperature dependence.
Magnetic moment: A vector quantity that measures the strength and orientation of a source of magnetic fields. The law describes the collective response of magnetic moments.
Magnetic susceptibility measurement: Experimental determination of a material’s magnetization response to an applied magnetic field. Temperature-dependent measurements provide the data fitted to the law.
Langevin theory of paramagnetism: A classical model of paramagnetism based on independent permanent magnetic dipoles in thermal equilibrium. It describes noninteracting dipoles and leads toward Curie-law behavior without collective ordering.
Curie law: A relation stating that an ideal paramagnet’s susceptibility is inversely proportional to absolute temperature. It is the noninteracting limit that the Curie–Weiss law extends.
Paramagnetism: A form of magnetism in which magnetic moments weakly align with an applied field and lose alignment when it is removed. The law characterizes susceptibility in the paramagnetic regime.
Curie–Weiss fit: A fit of inverse magnetic susceptibility to a linear function of temperature. Its slope and intercept estimate the Curie constant and Curie–Weiss temperature.
Heisenberg model: A quantum model of spins coupled through pairwise exchange interactions. It treats microscopic interactions explicitly rather than replacing them with a mean field.
Mean-field theory: An approximation that replaces interactions among many components with an effective average influence. It explains how collective interactions produce the law’s temperature offset.
Absolute temperature: Temperature measured from absolute zero, usually in kelvins. The inverse-temperature dependence uses absolute, not Celsius, temperature.

Linked from 5 pages