A laser scanning microscope with a thermal spot size of about 4 μm is used to measure a quantity proportional to the rf current density in an operating superconducting co-planar waveguide microwave resonator. The twinning of the LaAlO3 substrate produces a meandering of the current at the edges due to irregularities in the wet etching of the YBa2Cu3O7−δ film associated with substrate twin domai...

This paper will deliver insight into technology and physics of the levitation system for the SupraTrans project, a prototype of a superconducting transportation system. The technology used herein bases on the flux pinning in melt-textured bulk YBa2Cu3O7−X (YBCO) that stabilizes the lateral and the vertical position of the vehicle above the magnetic track. A track made from permanent magnets and...

We study the magnetic flux landscape in YBa2Cu3O7−x thin films as a two dimensional rough surface. The vortex density in the superconductor forms a self-affine structure in both space and time. This is characterized by a roughness exponent α = 0.76(3) and a growth exponent β = 0.57(6). This is due to the structure and distribution of flux avalanches in the self-organized critical state, which i...

Results of ab initio calculations on uniaxially strained YBa2Cu3O7 are correlated with known values of the uniaxial strain dependencies dTcydea sa ­ x, y, zd of the superconducting critical temperature Tc . Internal strains are found to dominate the strain dependence, with the strong nontetragonality correlating directly with the measured nontetragonality of dTcydea . Charge rearrangements with...

We explore the interplay between the mass anisotropy and the uniaxial pinning of tilted columnar defects (CD) in a YBa2Cu3O7 single crystal. At high temperatures T and fields H a sharp peak in the irreversible magnetization Mi at the direction of the tracks signals the presence of the CD. At low T such a peak is not observed, and the influence of the CD appears only as a perturbation to the ang...

We present an angle dependent nuclear quadrupole resonance (ADNQR) method to determine the electric field gradient asymmetry parameter eta in systems where the resonance line is so broad that the radio frequency field can excite only a portion of the nuclear spins. In this situation, the recently developed spectroscopic methods are not applicable. ADNQR is useful for single crystals and oriente...

Spectral features induced by 45 in-plane misoriented grains have been observed in the far infrared magneto-transmission of YBa2Cu3O7−δ thin films. Two strong dispersive features are found at 80 and 160 cm−1 and a weaker one at 116 cm−1. The data can be well represented by Lorentzian oscillator contributions to the conductivity. Several possible interpretations are discussed. We conclude that th...

Active thermal control of a reactor for YBa2Cu3O7-x chemical vapor deposition is studied using a nonlinear heat transfer model validated by preliminary component testing. LQR and LQE methods are applied to the linearized model for observer-based control. Convergence rates of the controller and observer are indicated by closed-loop eigenvalues and disturbance rejection is assessed with H2 and H∞...

We discuss various mechanisms that can lead to interband sign reversal of the order parameter in a multiband superconductor. In particular, we generalize Abrikosov-Gor’kov solution of the problem of weakly coupled superconductor with magnetic and nonmagnetic impurities on the case of arbitary order parameter anisotropy, including extreme cases as d−pairing or interband sign reversal of the orde...

Mechanical properties of the orthorhombic phase of YBa2Cu3O7-δ (Y-123) at room temperature have been investigated at different applied loads using nanoindentation technique. The study was carried out for several monodomains on the (001) planes for textured Bridgman samples with dispersed Y2BaCuO5 (Y-211) particles as pinning centers. The yield strength (σys), shear stress (τm) and toughness (KI...