Condensed Matter Physics Glossary

An energy range in a solid where no electron states exist, separating the valence band from the conduction band.

States that electron wavefunctions in a periodic potential are plane waves modulated by a periodic function with the lattice periodicity.

A state of matter in which a macroscopic number of bosons occupy the lowest quantum state at ultralow temperatures.

The fundamental domain of crystal momentum space (reciprocal space) defined by the Wigner-Seitz cell of the reciprocal lattice.

A pair of electrons with opposite momentum and spin that are bound together by phonon-mediated attraction in a superconductor.

The temperature at which a phase transition occurs, such as the superconducting transition temperature ($T_c$) or the Curie temperature.

The temperature above which a ferromagnetic material loses its spontaneous magnetization and becomes paramagnetic.

A model of the phonon contribution to specific heat that treats the solid as an elastic continuum with a maximum cutoff frequency.

The number of quantum states available per unit energy at a given energy level in a system.

A quasiparticle whose energy-momentum relation is linear, mimicking massless relativistic particles. Found on the surface of topological insulators and in graphene.

A quantum mechanical effect arising from the indistinguishability of electrons that gives rise to magnetic ordering in solids.

A state of interacting fermions whose low-energy excitations are long-lived quasiparticles, as described by Landau's theory.

The surface in momentum space separating occupied from unoccupied electron states at absolute zero temperature in a metal.

Quantization of Hall conductance at fractional multiples of $e^2/h$ in strongly correlated 2D electron systems, involving quasiparticles with fractional charge.

The physical dimension of the repeating unit cell in a crystal, typically measured in angstroms.

A quantized spin wave; the collective excitation corresponding to a deviation of spins from their ground-state alignment in a magnetic material.

The expulsion of magnetic flux from the interior of a material as it transitions to the superconducting state.

A material that band theory predicts to be metallic but is insulating due to strong electron-electron correlations.

The temperature above which an antiferromagnetic material becomes paramagnetic.

A measurable quantity that is zero above and nonzero below a phase transition, characterizing the degree of order in the system.

A quantized mode of vibrational energy in a crystal lattice, analogous to a photon for electromagnetic radiation.

An emergent excitation in a many-body system that can be described as a particle with renormalized properties.

The Fourier transform of a real-space Bravais lattice, used to describe diffraction conditions and electronic band structure.

A phenomenon in which a material exhibits zero electrical resistance and perfect diamagnetism below a critical temperature.

A material with an insulating bulk and symmetry-protected metallic surface or edge states that are robust against perturbations.