A model is developed for photoinduced absorption from localized states observed in femtosecond pump-probe experiments in high-Tc superconductors and other materials. The dynamics of localized carriers are described in terms of phenomenological approach similar to that originaly proposed by Rothwarf and Taylor. Expanding the relaxation rate in powers of the order parameter we have shown that den...

In cuprates superconductors (as polycrystal and single crystal samples) unusual hysteretic temperature behavior of elastic properties is frequently observed. In this work from the uniform point of view detailed analysis this abnormal temperature behavior of elastic properties is given. It is shown that the hysteretic temperature dependencies of elastic properties of YBa2Cu3O7−δ crystal are stro...

A heterostructure comprised of a 2.7 nm 7 unit cell thick layer of the metallic ferromagnet La2/3Ca1/3MnO3 and two 50 nm thick layers of the high-temperature superconductor YBa2Cu3O7 epitaxially grown on 100 SrTiO3 by pulsed-laser deposition was characterized by magnetization measurements and spherical-aberration-corrected high-resolution transmission electron microscopy HRTEM . The saturation ...

Several experiments were carried out to study the origin of the anomalous photovoltaic eff'ect in high-quality YBa2Cu307 thin films. In particular, the issue of whether the signal is induced by thermal gradients was addressed. Using samples with well-characterized orientation and texture, and using low-power cw lasers, it was determined that the signal was proportional to the thermal gradient a...

We describe small-angle neutron scattering (SANS) studies of vortex structures in the high Tc superconductor YBazCu307 in the mixed state. The SANS technique is a unique tool for probing the crystallography of a flux line arrangement in the bulk sample that can measure the values of the characteristic lengths and the effect of defects on lattice arrangement and orientation extremely accurately....

Crystal-Lattice Coupling to theVortex-Melting Transition in YBa2Cu3O7 R. Lortz, C. Meingast, U. Welp, W. K. Kwok, and G.W. Crabtree Forschungszentrum Karlsruhe, Institut für Festkörperphysik, 76021 Karlsruhe, Germany Fakultät für Physik, Universität Karlsruhe, 76131 Karlsruhe, Germany Materials Science Division and Science and Technology Center for Superconductivity, Argonne National Laboratory...