Low-dimensional Superconductors And The Study Of The Transport Properties Of The Junction

Recently, the research of the superconductivity of Sr2RuO4has become the mostinteresting topics. Many theoretical and experimental studies show that the superconductivityof Sr2RuO4may be spin triplet and have an odd-parity (p-wave) pairing state. Tunnelingspectra depend heavily on the symmetry of the pair potential in the superconductor. Therefore,the tunneling spectroscopy is a very sensitive tool for a superconductive study. Due to theformation of zero-energy states (ZES), there is a zero-bias conductance peak (ZBCP) inspin-triplet p-wave pairing state. There are zero-bias conductance peaks in the experiment ofthe Sr2RuO4superconductor junctions.Graphene consists of only one atomic layer of honey comb carbon atoms in crystal.Through neighbor effect on graphene can generate superconducting state. Superconductingcurrents have been observed in experiment.In the following chapter, by using the method of quantum statistics, we study thetunneling conductance in ferromagnetic semiconductor/ferromagnetic p-wave superconductorjunction, the spin-polarized transport in quantum-wire/ferromagnetic-insulator/p-wavesuperconductor junction at finite temperature and switching effects in superconductor/ferromagnet/superconductor graphene junctions.The dissertation consists of four chapters:In chapter one, we briefly introduce the basic knowledge of superconductor, the Andreevreflection properties in superconductor tunnel junction， the Josephson effects insuperconductor tunnel junction, and the graphene.In chapter two, we solve a self-consistent equation for the p-wave ferromagnetic p-wavesuperconductor gap. We study the spin-polarized quasiparticle transport coefficients and thedifferential conductance in ferromagnetic semiconductor/ferromagnetic p-wavesuperconductor junction.In chapter three, by using the extended Blonder-Tinkham-Klapwijk approach, we studytunneling conductance in quantum-wire/ferromagnetic-insulator/p-wave superconductorjunction at finite temperature. We investigate the effect of the ferromagnetic exchange energyand the temperature in the conductance spectra.In chapter four, the Josephson effects in the superconductor/ferromagnet/superconductor (SFS) graphene Josephson junction are studied by using the DiracBogoliubov-de Gennes (DBdG) formalism.