normalstate

Normalstate, in scientific usage, refers to the state of a physical system when it does not exhibit the macroscopic order associated with a broken symmetry or a specialized phase. It is often described as the baseline or standard phase against which ordered states are compared. The term is most common in condensed matter physics, where it denotes the phase in which no long-range order parameter is present, such as no superconducting condensate or no magnetic alignment.

In practice, the normal state is typically the phase above a transition temperature or above the conditions that stabilize an alternative order. For example, in superconductors the normal state is the metallic phase above the critical temperature Tc, where electrical resistance is finite and there is no Cooper-pair condensate. In magnetic materials, the normal state is usually the paramagnetic or disordered phase above the Curie or Néel temperature, where net magnetization vanishes in zero field. In many-body theory, the normal state is the regime where standard frameworks like Fermi-liquid theory apply, though some materials exhibit unusual (non-Fermi-liquid) behavior in their normal state.

The concept is also used more broadly to distinguish uncondensed or non-ordered phases from specialized states such as superfluids, Bose–Einstein condensates, or crystalline/ferromagnetic phases. While the specifics of the normal state depend on the system and context, it generally denotes the absence of the long-range order that defines the alternative phase.

See also: superconductivity, phase transition, order parameter, paramagnetism.