molecular field theory

Molecular field theory, developed by Pierre-Ernest Weiss, is a concept in magnetism that explains ferromagnetism. It proposes the existence of an internal magnetic field, known as the molecular field, which acts on individual atomic magnetic moments within a material. This theory successfully describes ferromagnetic behavior and phenomena like the Curie point, the temperature at which a ferromagnetic material loses its spontaneous magnetization. The theory also predicted spontaneous magnetization in small regions called Weiss domains. This internal field arises from quantum mechanical effects, specifically the exchange interaction, which aligns electron spins within the material.12