We investigate a model where superconducting electrons are coupled to a frequency dependent charge-density wave order parameter Delta_{r}(omega). Our approach can reconcile the simultaneous existence of low-energy Bogoljubov quasiparticles and high energy electronic order as observed in scanning tunneling microscopy (STM) experiments. The theory accounts for the contrast reversal in the STM spe...

Matveev and Larkin calculated the parity effect on the ground state energy of a small superconducting particle in the regimes where the mean level spacing δ is either large or small compared to the bulk gap ∆. We perform a numerical calculation which extends their results to intermediate values of δ/∆.

A STUDY OF Nb 3 (A1.75Ge.2 5 ) AND V3 Au SUPERCONDUCTING TUNNEL JUNCTIONS by JAMES ALLEN GREGORY Nb3(Al 75Ge2 5 ) Pb7Bi3 and V3Au-In superconducing tunnel junctions have been fabricated. Various methods of surface preparation, oxidation, and junction fabrication have been investigated. The tunneling data obtained from the Nb3(A17 5Ge2 5 ) junctions indicate a superconducting energy gap, 2A, of ...

: The doping-dependent evolution of the d-wave superconducting state is studied from the perspective of the angle-resolved photoemission spectra of a high-Tc cuprate, Bi2Sr2CaCu2 O8+δ (Bi2212). The anisotropic evolution of the energy gap for Bogoliubov quasiparticles is parametrized by critical temperature and superfluid density. The renormalization of nodal quasiparticles is evaluated in terms...

The TRASCO project for nuclear waste transmutation [1] requires a 5-100 MeV linac for acceleration of a 30 mA proton beam. Generally, room temperature Drift Tube Linac structures are used in this energy range; however, since the high duty cycle required for high current beams implies a very high power density on the resonators walls, the superconducting solution would offer many advantages. Amo...

We report measurements of bolometric absorption and absolute reflectivity of a thin film of NbN on a silicon substrate, above and below the superconducting transition temperature of 13.3 K. The opening of the gap at an energy of 3.9 kB Tc is seen clearly in both types of measurement. The data are compared with the predictions of the Mattis-Bardeen theory. The change in the reflectivity and the ...

We describe an experiment in superconductivity suitable for an advanced undergraduate laboratory. Point-contact spectroscopy is performed by measuring the differential conductance between an electrochemically etched gold tip and a 100-nm superconducting niobium film with a transition temperature Tc ≈ 7 K. By fitting the results to Blonder-Tinkham-Klapwijk theory using a finite lifetime of quasi...

Magnetic excitations in Ba(Fe0.94Co0.06)2As2: are studied by polarized inelastic neutron scattering above and below the superconducting transition. In the superconducting state, we find clear evidence for two resonancelike excitations. At a higher energy of about 8 meV, there is an isotropic resonance mode with weak dispersion along the c direction. In addition, we find a lower excitation at 4 ...

The superconducting compound LiFeAs is studied by scanning tunneling microscopy and spectroscopy. A gap map of the unreconstructed surface indicates a high degree of homogeneity in this system. Spectra at 2 K show two nodeless superconducting gaps with Δ(1)=5.3±0.1 meV and Δ(2)=2.5±0.2 meV. The gaps close as the temperature is increased to the bulk T(c), indicating that the surface accurately r...