Electronic structure of YBa 2 Cu 3 O 7 ceramics at the MP 2 electron correlation level

Electromagnetic, atomic structure and chemistry changes induced by Ca-doping of low-angle YBa2Cu3O7-delta grain boundaries.

Practical high-temperature superconductors must be textured to minimize the reduction of the critical current density J(gb) at misoriented grain boundaries. Partial substitution of Ca for Y in YBa(2)Cu(3)O(7-delta) has shown significant improvement in J(gb) but the mechanisms are still not well understood. Here we report atomic-scale, structural and analytical electron microscopy combined with ...

Probing the Electronic Structure of Y - B a - C u - O Superconductors by Copper NQR/NMR

The paper discusses some N Q R / N M R studies performed on Y B a C u O superconductors at the University of Zürich. It is shown how the resonance methods can yield information on electronic properties of quite different character. The review deals with: (1) the temperature and pressure dependence of Cu N Q R frequencies in YBa 2 Cu 4 O g (1-2-4); (2) an NQR study of the properties of Ca substi...

nd - m at . s up r - co n ] 2 9 A ug 2 00 2 Direct Correlation between Tc and CuO 2 Bilayer Spacing in YBa 2 Cu 3 O 7 − x

Femtosecond response of quasiparticles and phonons in superconducting YBa(2)Cu(3)O(7-δ) studied by wideband terahertz spectroscopy.

We measure the anisotropic midinfrared response of electrons and phonons in bulk YBa(2)Cu(3)O(7-δ) after femtosecond photoexcitation. A line shape analysis of specific lattice modes reveals their transient occupation and coupling to the superconducting condensate. The apex oxygen vibration is strongly excited within 150 fs, demonstrating that the lattice absorbs a major portion of the pump ener...

Frequency Shifts and Linewidth Changes of Infrared-active Phonons in Double-layered High-temperature Superconductors

(Received) We calculate frequency shifts and changes in linewidths of infrared-active phonons within a shell model for the bare phononic system coupled to an electronic double-layer structure with inter-layer charge transfer. The theoretical concept is applied to YBa 2 Cu 3 O 7 yielding a good description of experimental results in the normal state as well as at the transition to the supercondu...