Landau's Theory of Phase Transitions

Landau's Theory of Phase Transitions explains how materials change their properties, like from a solid to a liquid, by analyzing an order parameter—an observable that signals the transition. Near the transition point, small changes in temperature or pressure cause the system to shift gradually, with the order parameter smoothly evolving. The theory uses mathematical concepts to describe these changes, emphasizing that the nature of the transition depends on how the order parameter behaves, whether it changes continuously (second-order) or abruptly (first-order). It provides a framework to understand and classify different types of phase transitions systematically.