IJERT-Growth of Superconducting Nano Films of YBaCuO by Spray Pyrolysis Technique and Study of Quantum Interference Effects (original) (raw)
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Bicrystal junctions and superconducting quantum interference devices in YBa2Cu3O7 thin films
Journal of Applied Physics, 1994
Josephson junctions and superconducting quantum interference devices (SQUIDS) were made by depositing thin films of YBa,Cu,O, on bicrystal substrates of Y-ZrOz and SrTiOs. The critical current density of the junctions at 77 K could be adjusted from 100 to lo6 A/cm* by selecting bicrystals with misorientation angles 19 from 45" to 0". Current-voltage curves from junctions with 022" followed the resistively shunted junction model with noise rounding close to the transition temperature. The response of the critical current to magnetic fields was Fraunhofer-like and the width (w) dependence was l/w2 due to flux focusing effects. Shapiro steps under microwave radiation were observed. SQUIDS based on these junctions had energy resolutions at 77 K down to 8.6X 10e3' J/Hz and a 10 Hz flux noise level down to 1.5 X 10e9 @Hz at 85 K. A SQUID of the Ketchen design with a flux focusing washer had a magnetic field sensitivity of 15 pT/,iHz at 77 K. The temperature dependence of the voltage modulation depth close to T, was examined and found to be in agreement with theory [K. Enpuku, Y. Shimomura, and T. Kisu, J. Appl. Phys. 73, 7929 (1993)].
Microwave Measurements on YBaCuO Thin Films and Realisation of Microwave Superconducting Devices
Le Journal de Physique IV, 1996
Two characterisations methods in microwaves are presented. They permit to obtain IS*, Rs and h for a HTS film without the need of any theoretical model for the superconductivity. The best film tested exhibits at 35GHz and 78K a Rs value of LO&. at least three times lower than the copper one. A quasi-integrated oscillator has been realised on a lcm2 area: it oscillates at 12GHz and close to liquid nitrogen temperature. At lower temperatures an output power of +3&m and a phase noise of-100&cMz at JOOkHz from the carrier have been recorded.
Characterization of thin superconducting YBaCuO-films by Raman-spectroscopy
Zeitschrift f�r Physik B Condensed Matter, 1988
We have investigated thin sputtered films of the high T~ material YBa2Cu307 by means of Raman spectroscopy at different stages of the preparation process. We find that the films are amorphous after sputtering. The Raman spectra indicate that random polycrystalline layers, as well as crystalline layers with preferred orientation, are obtained by an additional thermal treatment.
“Double superconducting transition” in YBCO thin films
Physica C: Superconductivity, 2002
Two 150 nm thick YBCO films have been investigated using flux noise and complex conductance measurements. In both experiments thermally excited vortices are studied. The first film shows a single transition, with T c % 88:2 K and DT c % 0:3 K, while the second film shows a two-step transition with T c1 % 90:1 K and DT c % 0:1 K, and T c2 % 89:8 K and DT c % 0:15 K. The experimental results obtained for the double transition sample in combination with computer simulation data in Medvedyeva et al. (in this volume) indicate that this sample can be described as two weakly coupled homogeneous superconducting layers, one on top of the other, with different critical temperatures.
Preparation of YBCO superconducting films by spray deposition and MTG processing
Materials Letters, 1995
Superconducting YBCO films (T, = 88 K, J, = 4200 A/cm* (77 K, 0 T) ) were prepared using spray deposition and melttextured growth (MTG) processing. The influence of different substrates and the metal atom ratio Y:Ba:Cu in the initial solutions on the structure and properties of the films obtained was studied.
Investigation of superconducting thin films and multilayered structures for electronic applications
2014
The grand challenge in twenty-first-century physical and material sciences is related to enabling continued advances in information processing and data storage beyond conventional silicon based electronics. Recent researches in oxide electronics suggest that it may be plausible to implement complex systems at the device level, thereby drastically increasing computational density and power efficiency. High temperature superconducting (HTS) ceramics YBa 2 Cu 3 O 7-δ (YBCO) is currently one of the most promising candidates for the creation of sophisticated cryo-electronic devices such as: Josephson junctions, microwave filters, single photon detectors, and etc. One of the important problems in YBCO thin film technology is an enhancement of superconducting properties of epitaxial films which allows the creation of reliable cryo-electronic devices with high performances. Heteroepitaxial structures consisting, for example, of YBCO layers and layers of different superconducting v ACKNOWLEDGEMENTS I would like to express my deepest sincere appreciation my supervisor Professor Alexey Pan for his valuable advices, suggestions, guidance, patience and constructive critics through the completion of my thesis work. I also would like to thank all Thin Films Team members especially Dr. Olga Shcherbakova and Igor Golovchanskiy, as well as the other ISEM staff. It had been a pleasure working with all of you. My sincerest thanks are extended to all my friends in our group. Thanks for your constant support and contributions. vi TABLE OF CONTENTS
Effects of Yttrium Oxide Inclusions on the Orientation and Superconducting Properties of YBCO Films
2013
The formation of Y2O3 secondary phase in the films of YBa2Cu3O7 (YBCO) high-temperature superconductor is of large interest because Y2O3 inclusions can increase the critical current density (Jc) in YBCO films. We studied Y-rich and Y-poor YBCO films prepared by the MOCVD method. Y2O3 phase appeared in the Y-rich films as small (20x10 nm) oriented particles distributed throughout the YBCO films. It was found that at the same growth conditions Y-rich YBCO films grew highly c-oriented, whereas in the Y-poor films both aand c-oriented YBCO grains were present. The Y-rich films exhibited better superconducting properties (Jc) because of better YBCO texture and magnetic flux pinning on the Y2O3 inclusions.
Effect of Ca doping in YBCO superconducting thin films
Physica C: Superconductivity, 2004
We investigate the effect of partial substitution of Y by Ca in YBCO superconducting thin films. The films were grown on (1 0 0) SrTiO 3 single crystal substrates by pulsed laser deposition (PLD). The Ca doped film were ablated from Y 1Àx Ca x Ba 2 Cu 3 O 7Àd targets with x ¼ 0, 0.05, 0.07, and 0.10. The dc transport properties of the films in applied magnetic field are analyzed to study the role of Ca on the superconducting properties of YBCO films. The irreversibility line for the samples with x ¼ 0 and 5 at.% Ca was derived from the E-J curves using a scaling theory for the vortex-glass transition.
IEEE Transactions on Applied Superconductivity, 2003
YBa 2 Cu 3 O x (YBCO) thin films on single crystal LaAlO 3 substrates were prepared from a trifluoroacetate (TFA) precursor heat treated in a low oxygen partial pressure argon atmosphere. The purpose of the study was to explore the possibility of forming high-purity, epitaxial YBCO films at heat treatment temperatures and oxygen partial pressures low enough to allow the TFA process to be adapted to metallic substrates. The formation of a superconducting YBCO phase was confirmed by measuring the critical temperature (T c ) inductively. In-plane texture and c-axis alignment of the films were determined from x-ray phi scans and omega scans, respectively. Raman microspectroscopy was used to interrogate grain connectivity, oxygen stoichiometry, c-axis verticality with respect to the substrate, and second phase formation. The optimum heat treatment temperature was found to be near 750 • C in an argon atmosphere, the equivalent oxygen partial pressure, which was about 10 −5 atm. The full-width half-maxima (FWHMs) of the YBCO (113) phi and (005) omega scans for a sample prepared at 750 • C were about 0.6 and 0.5 • , respectively, which indicates that the film was epitaxial. This film showed a sharp superconducting transition at 91 K and an inductive critical current density of 1.3 MA cm −2 at 77 K. The ability to form high-quality YBCO films under the conditions used is consistent with the thermodynamic predictions that the optimal heat treatment temperature decreases as oxygen partial pressure decreases. The results of this study define YBCO formation conditions for TFA-based precursors that may be suitable for application on metallic substrates.
DEPOSITION TECHNIQUES FOR HIGH-Tc SUPERCONDUCTING YBCO THIN FILMS
Many application of high temperature superconductor in advance technology usually require the superconductor in the form of thin films. In this paper attempts has been made to summarize the most popular growth techniques such as Co-evaporation sputtering, laser ablation, and chemical vapor deposition of high-T c superconducting thin films.