Epitaxial thin films of YBa2C!u307 have been prepared on SrTiOs and LaAlOs substrates by a high-pressure planar dc-sputtering technique. By covering the substrate heater with a frame of polycrystalline YBazCu30~ -substantial improvements of the YBa2Cu307 film properties were achieved. These are characterized by dc-resistivity values p(T) of less than 50 @I cm at 100 K and ~(300 K)/p( 100 K) values of up to 3.9. Significant deviations from the usual linear p(T) behavior were found. Critical temperatures above 90 K, resistive transition widths down to 0.3 K, and critical current densities of about 5 x lo6 A/cm2 at 77 K confirm the high quality of the films. As indicated by Rutherford backscattering and high-resolution transmission electron microscopy the films exhibit a microstructure characterized by a reduced density of lattice defects. However, lattice-coherent precipitates with a diameter of about 5-10 nm were observed. As an outstanding feature the films exhibit, besides the initial steep falloff at T, a further gradual decrease of the microwave surface resistance at 87 GHz below 50 K by at least one order of magnitude. These results are very promising for millimeter-wave applications of epitaxial YBaz.Cu307 thin films.

No abstract

No abstract

Articles you may be interested inFerroelectric domains in epitaxial PbTiO3 films on LaAlO3 substrate investigated by piezoresponse force microscopy and far-infrared reflectance J. Appl. Phys. 110, 084115 (2011); 10.1063/1.3651510 Far-infrared transmission in GaN, AlN, and AlGaN thin films grown by molecular beam epitaxy J. Appl. Phys.A technique for measuring the far-infrared radiative properties of metal and superconducting thin films AIP Conf.

No abstract