Excitonic “superfluidity” in low-dimensional crystals

The “superfluid” properties of layered metallic crystals comprising conducting sheets of electrons and holes are predicted. The excitonic pairing in such anisotropic system manifests itself in alternating diamagnetic response to small longitudinal fields and, at sufficiently high fields (H| and E⊥), in the oscillating Josephson currents flowing in the direction perpendicular to the sheets.