Boundary Effects on the Transition into Excitonic Phase

Abstract

AbstractThe boundary influence on the transitions of semiconductors or semimetals into the excitonic phase is considered. Proximity effects lead to a decreasing of the dielectric gap in the excitonic phase near the boundary with vacuum or an insulator. In the case when two contacting materials have different critical transition temperatures (T and T) in the excitonic phase, the sample with the low critical temperature becomes insulator for temperature T > T > T. On taking into account the hybridization and interband transition the Ginzburg‐Landau equation for the effective order parameter describing the semimetal–“excitonic insulator”; phase transition is derived. The equation describing the proximity effects in the transition semiconductor‐“excitonic insulator” is equivalent to the equation for Wannier‐Mott excitons near the boundary.