SUPERFLUIDITY AND PLANAR VORTICES IN SYSTEMS WITH PAIRING OF SPATIALLY SEPARATED ELECTRONS AND HOLES

摘要

A possibility of pairing of spatially separated electrons and holes (PSSEH), and transition of the formed pairs into a rather unusual superconducting state, in which electron supercurrent is accompanied by hole supercurrent that is equal to the former one in value and opposite in direction, was predicted by Lozovik and Yudson, and independently by Shevchenko. An opportunity of Bose-condenstion of electron-hole pairs in the systems without spatially separated electrons and holes and various manifestation of such condensation, in particular, a possibility of superfluidity of pairs was discussed long before the appearance of the works by Lozovik, Yudson and Shevchenko. However, in such systems the interband transitions which are always exist in real physical systems lead to fixation of phase of an order parameter due to electron-hole pairing. This induces the appearance of a gap in an energy spectrum and, as a result, the transition takes place into a dielectric state and not into superfluid one.