An unusual superconductivity mechanism in systems with pairing of spatially separated electrons and holes

Bose-Einstein Condensation of Excitons in Planar Systems and Superconductive Phase Transition Temperature

“…One should notice that the expression in the curled brackets represents Bose planar statistics effect and very small values of α (α 1) are needed for getting superconductivity effects. This conclusion is essentially different from that obtained in previous works [16][17][18][19][20][21][22].…”

“…The consistent relation given by (35) is similar to a consistent equation given by BCS [40], but the distribution in internal momentum space, due to electromagnetic interactions, included in the summation of (35) is completely different, as will be analyzed here. It is different from a selfconsistent equation obtained in previous works for excitons related to the BCS theory [16][17][18][19][20][21][22], since this equation has been obtained here only by assuming planar Bose statistics for high density of excitons where the attractive interaction between excitons is coupled with changes in excitons' internal momenta or correspondingly with their internal energies. As this equation can be applied only by inserting the full Bose statistics in the summation over k, the development of this equation gives results which are essentially different from those of BCS and from those obtained previously about the self-consistent equation for excitons [16][17][18][19][20][21][22].…”

“…Superconductive exciton effects have been predicted by certain theories [16][17][18][19][20][21][22] which have been developed quite long ago, but experiments have not confirmed, so far, such predictions. It has been claimed in certain works [23,24] that excitons do not have perfectly bosonic commutation relations at high densities.…”

Coherent exciton transport in semiconductors

“…The first hint is a huge enhancement of inter-layer tunneling solely due to many-body effects, clearly pointing to strong inter-layer coherence [250]. The most compelling observations are based on counterflow measurements [238,167,254], where the electric currents of opposite sign and like magnitude that flow in the two layers provide zero total electric current and a net exciton flow. For filling factors other than ν T = 1 the Hall voltages separately measured in the two layers are equal and opposite in sign, whereas for ν T = 1 they both drop to zero, consistently with the flow of an uncharged object such an exciton [132,266,283].…”

Bilayer Excitons in Two-Dimensional Nanostructures for Greatly Enhanced Thermoelectric Efficiency

“…In a bulk material, the electron and hole can recombine and thus annihilate the exciton. In order to avoid this annihilation, it has been proposed to spatially separate the electrons and holes in two different layers [20,21]. Such a heterostructure of a p-type and n-type material can support bilayer excitons.…”