Polaron

The polarons designate special quasiparticles which form the basis of the local polarization of the crystal lattice by charged particles. The polaron is a fermionic quasiparticles in all cases and should not be confused with the polariton ( a bosonic quasiparticles ).

When electrons move through a crystal, they produce due to their electric charge is surrounded by an Polarization: the neighboring electrons are pushed back a bit due to the repulsion of like charges, attracted the adjacent positive ion cores, however.

This " polarization cloud" moves together with the electron and causes an increase in the effective mass, particularly in so-called polar crystals (eg with different ionic charges ). The deformations that are generated in this way, one belongs to theoretical assumptions to independent quasiparticles, called polarons.

Polarons can not only come from electrons, but also protons, deuterons or muons. Further, in the magnetic crystals, so-called magnetic polaron in which a kind of magnetization cloud entrained.

The electron-phonon interactions in the formation of Cooper pairs in superconductors first kind can be modeled as a polaron.