normalmetal

Normal metal is a metal that does not display superconductivity or other non-classical electronic states under ordinary conditions. In condensed matter physics, the charge carriers are described as electrons in a degenerate Fermi gas that behave approximately as a nearly free-electron system, as in the Drude-Sommerfeld model. The term contrasts with superconductors, which exhibit zero electrical resistance and the expulsion of magnetic fields below a critical temperature.

In a normal metal, electrical resistivity is finite at low temperatures due to impurities and defects; as temperature rises, resistivity increases primarily because of electron-phonon scattering. At moderate temperatures, electrons behave as a Fermi liquid, and the Wiedemann-Franz law relates electrical and thermal conductivities through the Lorenz number. The mean free path can be long in clean samples, enabling good conduction.

Common examples include copper, silver, gold, aluminum, and iron; these metals crystallize in common lattice structures and have well-defined Fermi surfaces.

A normal metal lacks a superconducting ground state and does not exhibit emergent phenomena tied to strongly correlated electron states at low temperatures. However, under certain conditions some materials can become superconductors, and at low temperatures other ordered states, such as magnetic order or charge-density waves, may appear in materials otherwise considered normal metals.

See also: superconductivity, Fermi liquid theory, Drude model, Wiedemann-Franz law.