Superconductivity in mesoscopic high-Tc superconducting particles

Abstract

Based on the Hubbard model in the framework of non-phonon kinematical mechanism and taking into account the discreetness of an electronic energy spectrum, the superconducting critical temperature of a mesoscopic high-Tc sphere is analyzed as a function of doping and as a function of a particle's radius. The critical temperature Tc is found to be an oscillating function of the radius of a particle. The size-dependent doping regime is revealed in high-Tc nanoparticles. Our analysis shows that each oscillation in Tc corresponds to the increase of a number of the energy levels in the sphere by one. The amplitude of oscillations of Tc increases with decreasing R and can reach a value of 6 K for nanopartilces with sizes about 25 nm, in a good agreement with experimental studies of YBa2Cu3O 7−δ nanoparticles.

Shape resonances in the superconducting order parameter of ultrathin nanowires

“…Strong indications for such behaviour are found not only in ultrathin films but also in nanoparticles (see, for example, Refs. [5] and [6]) and superfluid nuclei [7,8] (as it had been predicted by Blatt and Thompson). Recently a new technique of electrodeposition into extended nanopores has been developed [9], which makes it possible to produce single-crystal nanowires of high quality.…”

“…A shape resonance in the dependence of the energy-gap parameter on the specimen dimensions can occur any time when an electron subband appearing due to the size quantization passes through the Fermi surface [4]. Strong indications for such behaviour are found not only in ultrathin films but also in nanoparticles (see, for example, Refs.[5] and [6]) and superfluid nuclei [7,8] (as it had been predicted by Blatt and Thompson). Recently a new technique of electrodeposition into extended nanopores has been developed [9], which makes it possible to produce single-crystal nanowires of high quality.…”

“…[5] and [6]) and superfluid nuclei [7,8] (as it had been predicted by Blatt and Thompson). Recently a new technique of electrodeposition into extended nanopores has been developed [9], which makes it possible to produce single-crystal nanowires of high quality.…”