Related papers: Superfluid anisotropy in YBCO: Evidence for pair t…
The effects of chain disorder on superconductivity in YBa_2Cu_3O_{7-\delta} are discussed within the context of a proximity model. Chain disorder causes both pair-breaking and localization. The hybridization of chain and plane wavefunctions…
Superfluid condensation can fundamentally be different from that predicted by the Bardeen-Cooper-Schrieffer (BCS) theory. In a broad class of low-carrier-density superconductors, such as granular aluminum, doped nitrides, and high-Tc…
Recently there has been reinvigorated interest in the superconducting proximity effect, driven by predictions of the emergence of Majorana fermions. To help guide this search, we have developed a phenomenological model for the tunneling…
We calculate the penetration depth $\lambda$ in the $a$, $b$ and $c$ directions for a simple model of YBa$_2$Cu$_3$O$_7$. In this model there are two layers---representing a CuO$_2$ plane and a CuO chain---per unit cell. There is a…
We argue that the results of recent scanning tunneling microscopy, angle-resolved photoemission and infrared spectroscopy experiments on the CuO chains of YBa$_2$Cu$_3$O$_{6+x}$ are consistently explained within a proximity model by the…
The existence of Josephson tunneling has been demonstrated between YBa$_2$Cu$_3$O$_{7-\delta}$ and Pb with the current flowing along the c-axis of YBa$_2$Cu$_3$O$_{7-\delta}$. This is presumed to come from an s-wave component of the…
Recent ARPES measurement observed a large $ab$-axis gap anisotropy, $\Delta(0,\pi)/\Delta(\pi,0)=1.5$, in clean YBa$_2$Cu$_3$O$_{7-\delta}$. This indicates that some sub-dominant component may exist in the $d_{x^2-y^2}$-wave dominant gap.…
This paper presents a general model for calculating the density of states and the Cooper pair potential in proximity coupled superconducting bi- and tri-layer films. The typical example of superconducting tunnel junctions is used to show…
Scanning tunneling spectroscopy was performed on c-axis Y{1-x}Ca{x}Ba2Cu3O{7-delta} thin films for x= 0, 0.05, 0.15 and 0.20 at 4.2K. The measured spectra show main-gap, sub-gap and satellite features which scale similarly in energy versus…
Within a microscopic two band model of planes and chains with a pairing potential in the planes and off diagonal pairing between planes and chains we find that the chains make the largest contribution to the Josephson tunnelling current and…
We probe directly the superconducting current-phase relations (CPR) of Nb/Au/(001) YBa2Cu3Ox heterojunctions prepared in epitaxial c-axis oriented YBa2Cu3Ox (YBCO) thin films. The measurements are performed by a single-junction interference…
We report a new class of $c$-axis Josephson tunneling experiments in which a conventional superconductor (Pb) is deposited across a single twin boundary of a YBa_2Cu_3O_{7-\delta} crystal. We measure the critical current as a function of…
The interlayer pair tunneling model of Anderson et al. is generalized to include the strong coupling effects associated with in-plane interactions. The equations for the superconducting transition temperature T_{c} are solved numerically…
We consider a new kind of superconducting proximity effect created by the tunneling of "spin split" Cooper pairs between two conventional superconductors connected by a normal conductor containing a quantum dot. The difference compared to…
Superconducting electrodes are an integral part of hybrid Josephson junctions used in many applications including quantum technologies. We report on the fabrication and characterization of superconducting hybrid Au/YBa2Cu3O7-x (YBCO)…
Recently, a strongly enhanced xy anisotropy of magnetic excitations was observed in YBa_2Cu_3O_y (YBCO_y) with y=6.45 and Tc=35 K [Science 319, 597 (2008)]. Unlike the observation in YBCO_6.6 and YBCO_6.85, the anisotropy grows to be…
The coupling between the superconducting planes of YBa2Cu3O{7-\delta}/ PrBa2Cu3O{7-\delta} superlattices has been measured by c-axis transport. We show that only by changing the thickness of the superconducting YBa2Cu3O{7-\delta} layers, it…
Proximity effect facilitates the penetration of Cooper pairs that permits superconductivity in normal metal, offerring a promising approach to turn heterogeneous materials into superconducting and develop exceptional quantum phenomena.…
We report a study of the basal-plane anisotropy of the superfluid density in underdoped YBa$_{2}$Cu$_{4}$O$_{8}$ (Y124), showing the effects of both the CuO$_{2}$ planes and the fully occupied CuO chains. From small-angle neutron scattering…
The resistivity and the Hall effect in the copper-oxide high-temperature superconductor YBa$_{2}$Cu$_{3}$O$_{7-\delta}$ (YBCO) are remarkably anisotropic. Using a thin film of YBCO grown on an off-axis cut SrTiO$_3$ substrate allows one to…