Landau-Ginzburg theory

Landau-Ginzburg theory is a framework in physics used to describe how materials change their properties, especially during phase transitions like from liquid to solid or magnetic to non-magnetic states. It uses a mathematical function called a "free energy" that depends on an order parameter—a quantity indicating the degree of order in the system. Near transition points, the behavior of this function reveals how the material shifts from one phase to another, capturing critical phenomena and predicting whether changes are gradual or abrupt. This approach provides a powerful way to understand complex collective behaviors in condensed matter systems.