Analysis of the interlayer infrared conductivity of cuprate high-transition temperature superconductors reveals an anomalously large energy scale extending up to midinfrared frequencies that can be attributed to formation of the superconducting condensate. This unusual effect is observed in a va- riety of materials, including Tl2Ba2CuO6+x, La2-xSrxCuO4, and YBa2Cu3O6.6, which show an incoherent...

We analyze the interplay of dissipative and quantum effects in the proximity of a quantum phase transition. The prototypical system is a resistively shunted two-dimensional Josephson junction array, studied by means of an advanced Fourier path-integral Monte Carlo algorithm. The reentrant superconducting-to-normal phase transition driven by quantum fluctuations, recently discovered in the limit...

Systems of superconducting islands placed on normal metal films offer tunable realizations of two-dimensional (2D) superconductivity1,2; they can thus elucidate open questions regarding the nature of 2D superconductors and competing states. In particular, island systems have been predicted to exhibit zero-temperature metallic states3–5. Although evidence exists for such metallic states in some ...

We experimentally demonstrate Cooper pairs' drastic enhancement of the band-to-band radiative recombination rate in a semiconductor. Electron Cooper pairs injected from a superconducting electrode into an active layer by the proximity effect recombine with holes injected from a p-type electrode. The recombination of a Cooper pair with p-type carriers dramatically increases the photon generation...

We present measurements of the superconducting transition temperature, Tc, for arrays of mesoscopic Nb islands patterned on Au films, for large island spacings d. We show that Tc ∼ 1/d(2), and explain this dependence in terms of the quasiclassical prediction that the Thouless energy, rather than the superconducting gap, governs the inter-island coupling at large spacings. We also find that the ...

We have measured the temperature dependence of the peak position and linewidth of the 42.5 meV phonon branch in a twinned single crystal of YBa 2Cu 3O 7 as a function of wave vector q. In the s100dys010d direction in the Brillouin zone, considerable softening and broadening occur below the superconducting transition temperature Tc at some values of q. We observe an order of magnitude smaller so...

We study states in the superconducting gap induced by magnetic impurities using self-consistent quantum Monte Carlo with maximum entropy and formally exact analytic continuation methods. The magnetic impurity susceptibility has different characteristics for T0 & Tc0 and T0 * Tc0 (T0: Kondo temperature; Tc0: superconducting transition temperature) due to the crossover between a doublet and a sin...

We present detailed thermodynamic and transport measurements on single crystals of the recently discovered binary intermetallic superconductor, SrSn(4). We find this material to be a slightly anisotropic three-dimensional, strongly coupled, possibly multiband, superconductor. Hydrostatic pressure causes a decrease in the superconducting transition temperature at the rate of ≈ - 0.068 K kbar(-1)...

A nested Fermi surface with nearly parallel orbit segments is found to yield a singlet d–wave superconducting state at high temperatures for a restricted range of the on–site Coulomb repulsion that avoids the competing spin density wave instability. The computed superconducting transition temperature drops dramatically as the nesting vector is decreased, in accord with recent photo–emission dat...

Two dimensional films comprising of Bi clusters ranging in size from 25 to 100 Å show an influence of the underlying matrix on normal state resistivity and the superconducting transition temperature Tc. This is in contrast to crystalline Bi. Quantum size effects are observed by changing the deposition temperature, which determines cluster size. These observations can be attributed to supercondu...