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A neutron-scattering study of nonsuperconducting La2-xSrxCaCu2O6 (x=0 and 0.2), a bilayer copper oxide without CuO chains, has revealed an unexpected tetragonal-to-orthorhombic transition with a doping dependent transition temperature. The predominant stru ...
We report on x-ray photoemission and absorption measurements on ruthocuprate and SrRuO3 samples. The ruthocuprates include samples that are both weak ferromagnets and superconductors for part of the phase diagram. The results indicate that adding hydrogen ...
We report on a distortion of Bi2Sr2CanCun+1 O6+2n+x (n = 0,1) single crystals, perpendicular to the CuO2 planes (the c-axis), for non-stoichiometric samples containing an excess of Bi. The distortion involves two parts: (a) symmetric displacements in the S ...
In YBa2Cu3O6+x the tetragonal to orthorhombic transition occurs around x equals 0.3, followed by a continuum variation of lattice parameters. Hence both, the structural and superconducting properties, depend upon the oxygen content in CuO chains. Conversel ...
We used a pump-probe technique to measure the transient change of optical reflectivity of both La2-xSrxCuO4, of various dopings, and slightly underdoped YBa2Cu3O7-x and NdBa2Cu3O7-x thin films. For the La2-xSrxCuO4 films, our data demonstrate the coexisten ...
Properties of ultra-thin films are different from their single crystal counterparts due to the presence of (substrate induced) strain, different degree and type of (growth induced) disorder and different average doping (distribution of oxygen vacancies, fo ...
Measurements of critical temperature T-c in superconducting YBa2Cu3O6.9 films with reduced long-range structural order show the validity of the empirical scaling relation Delta T-c proportional to r(c)(-2) between disorder-induced reduction of T-c and stru ...
The present study aims at a better understanding of the high piezoelectric properties encountered in lead-based ferroelectrics by focusing on the extrinsic contributions to the response. The main characteristics of these materials are the highly nonlinear ...
Observations by transmission electron microscopy (TEM) of the submicrometer phases present in calcium aluminate cements have shown that Ca-Al-Fe oxides coexist in two forms with brownmillerite (b) and perovskite (p) structures, respectively. Homogeneous si ...
Recent photoemission evidence for non-zero gap in highly overdoped Bi2Sr2-CaCu2O8+x, along the directions in the Brillouin zone where the d-wave gap exhibits nodes, is in accordance with more conventional behavior in strongly overdoped high-T-c cuprates. T ...