Mesoscopic charge-density-wave junctions

We investigate theoretically charge-density waves (CDW's) in mesoscopic heterostructures for the configuration where the one-dimensional chains are oriented normal to the interfaces. Based on Bogoliubov--de Gennes equations and suitable boundary conditions, ground state properties of phase coherent CDW systems are calculated in the mean-field approximation. It is shown that in a charge-density-wave/normal-metal/charge-density-wave junction the CDW condensates couple through the normal metal region by means of Friedel oscillations. Geometrical resonance effects are predicted. We relate the phase-dependent energy of the junction to a momentum current, carried by electron-hole pairs. The effects of pinning potentials at the interfaces are also considered. Finally, we discuss the analogies with superconductor and ferromagnet junctions. {} 1996 The American Physical Society.