Atomic Layer Deposition (ALD) is a process that synthesizes materials in successive monolayers, at rates up to 1 micron/hour. We have been using this technique at Argonne as a possible way to improve superconducting radio frequency (SCRF) cavities performances. Initial experiments using tunneling spectroscopy and ALD have led to a new model for dissipation mechanisms occurring at the surface an...

Raman scattering experiments on NaxCoO2.yH2O single crystals show a broad electronic continuum with a pronounced peak around 100 cm(-1) and a cutoff at approximately 560 cm(-1) over a wide range of doping levels. The electronic Raman spectra in superconducting and nonsuperconducting samples are similar at room temperature, but evolve in markedly different ways with decreasing temperature. For s...

Recent experiments implicate spins on the surface of metals as the source of flux noise in superconducting quantum interference devices and indicate that these spins are able to relax without conserving total magnetization. We present a model of 1/f flux noise in which electron spins on the surface of metals can relax via hyperfine interactions. Our results indicate that flux noise would be sig...

In this paper, a model of torque dependence of critical current in a Bi2223/Ag composite concentric cylinder is analyzed. Based on the hypothesis of planar section and elastic linear strengthening constitutive theory, the relation between torque and shear strain is firstly obtained. Then a linear weakening relation between critical current density and shear strain are put forward. Finally the e...

It is widely believed that temperature gradient does not induce electric field in the superconductor and consequently that thermoelectric effects do not exist, or are negligible in these materials. This statement is correct only as far as effective electric field or gradient of the electrochemical potential is concerned. In normal metals temperature gradient generates effective electric field, ...

The ~mostly! insulating behavior of PrBa2Cu3O72d is still unexplained and even more interesting due to the occasional appearance of superconductivity in this material. Since YBa2Cu3O72d is nominally isostructural and always superconducting, we have measured the electron momentum density in these materials. We find that they differ in a striking way, the wave function coherence length in PrBa2Cu...

We have found that crystalline Josephson junctions have problems with control of critical current density that decrease circuit yield. We present a superconducting quantum bit circuit designed to accommodate a factor of five variation in critical current density from one fabrication run to the next. The new design enables the evaluation of advanced tunnel barrier materials for superconducting q...

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 present an overview of recent superconducting quantum interference device (SQUID) research and development in Europe. History, theory and fundamental experiments and especially practical SQUIDs and SQUID readout were covered by Part I of this overview. Today, the SQUID itself is a rather mature device, the most sensitive magnetic flux and field detector, which finds use also as an amplifier....

Oxide heterostructures often exhibit unusual physical properties that are absent in the constituent bulk materials. Here, we report an atomically sharp transition to a ferromagnetic phase when polar antiferromagnetic LaMnO3 (001) films are grown on SrTiO3 substrates. For a thickness of six unit cells or more, the LaMnO3 film abruptly becomes ferromagnetic over its entire area, which is visualiz...