Condensed Matter Physics

Condensed matter physics deals with the physical properties of condensed phases of matter. These properties appear when a number of atoms at the supramolecular and macromolecular scale interact strongly and adhere to each other or are otherwise highly concentrated in a system. The most familiar examples of condensed phases are solids and liquids. Such every-day condensed phases arise from the electromagnetic forces between atoms. More exotic condensed phases include the mesophases of liquid crystal devices, the superconducting phase exhibited by certain materials at low temperature, the ferromagnetic and antiferromagnetic phases of spins on atomic lattices, and the Bose-Einstein condensate found in certain ultracold atomic systems.

Condensed matter physics seeks to understand the behavior of these phases by using well-established physical laws. In particular, these include the laws of quantum mechanics, electromagnetism and statistical mechanics. The diversity of systems and phenomena available for study makes condensed matter physics by far the largest field of contemporary physics. By one estimate, one third of all United States physicists identify themselves as condensed matter physicists. The field has a large overlap with chemistry, materials science, and nanotechnology, and there are close connections with the related fields of atomic physics and biophysics. Theoretical condensed matter physics also shares many important concepts and techniques with theoretical particle and nuclear physics.

Historically, condensed matter physics grew out of solid-state physics, now considered one of its main subfields. The name of the field was apparently coined in 1967 by Philip Anderson and Volker Heine when they renamed their research group in the Cavendish Laboratory of the University of Cambridge from "Solid-State Theory" to "Theory of Condensed Matter". In 1978, the Division of Solid State Physics at the American Physical Society was renamed as the Division of Condensed Matter Physics. One of the reasons for this change is that many of the concepts and techniques developed for studying solids can also be applied to fluid systems. For instance, the conduction electrons in an electrical conductor form a Fermi liquid, with similar properties to conventional liquids made up of atoms or molecules. Even the phenomenon of superconductivity, in which the quantum-mechanical properties of the electrons lead to collective behavior fundamentally different from that of a classical fluid, is closely related to the superfluid phase of liquid helium.