Theory of the Excitonic Insulator in the Presence of Normal Impurities

摘要: Recently several papers have discussed the possibility of a new kind insulating phase in semimetals or semiconductors with small band gap. This can be described as condensate electron-hole pairs (excitons) due to an effective interaction between valence and conduction electrons. paper extends analysis excitonic semimetallic region presence randomly distributed normal (i.e., nonmagnetic) impurities. It is shown that impurities pair-breaking effect similar case magnetic superconductors. The Abrikosov-Gorkov theory developed for latter applied minor modifications phase. beyond critical impurity concentration cannot exist. Changes transition temperature order parameter are calculated, well density states. found close excitation spectrum system has no energy