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Sample records for superconducting ybco films

  1. Preparation of YBCO superconducting films by spray pyrolysis method

    International Nuclear Information System (INIS)

    Mora Alonso, M.; Leyva Fabelo, A.; Rubio Frias, E.; Pupo Gonzalez, I.; Lopez Sanchez, D.

    1994-01-01

    The methodology for the preparation of YBCO superconducting films on Zr 2O (Y) substrates by spray pyrolysis method is reported. The transition temperature of these films is superior than the boiling temperature of liquid 2N . Other critical parameters are similar to those reported by other authors using the same technique

  2. Textured YBCO films grown on wires: application to superconducting cables

    International Nuclear Information System (INIS)

    Dechoux, N; Jiménez, C; Chaudouët, P; Rapenne, L; Sarigiannidou, E; Robaut, F; Petit, S; Garaudée, S; Porcar, L; Soubeyroux, J L; Odier, P; Bruzek, C E; Decroux, M

    2012-01-01

    Efforts to fabricate superconducting wires made of YBa 2 Cu 3 O 7 (YBCO) on La 2 Zr 2 O 7 (LZO) buffered and biaxially textured Ni-5 at.%W (NiW) are described. Wires were manually shaped from LZO buffered NiW tapes. Different diameters were produced: 1.5, 2 and 3 mm. The wires were further covered with YBCO grown by metal organic chemical vapor deposition (MOCVD). We developed an original device in which the round substrate undergoes an alternated rotation of 180° around its axis in addition to a reel-to-reel translation. This new approach allows covering the whole circumference of the wire with a YBCO layer. This was confirmed by energy dispersive x-ray spectroscopy (EDX) analysis coupled to a scanning electron microscope (SEM). For all wire diameters, the YBCO layer thickness varied from 300 to 450 nm, and the cationic composition was respected. Electron backscattering diffraction (EBSD) measurements were performed directly on an as-deposited wire without surface preparation allowing the investigation of the crystalline quality of the film surface. Combining EBSD with XRD results we show that YBCO grows epitaxially on the LZO buffered NiW wires. For the first time, superconductive behaviors have been detected on round substrates in both the rolling and circular direction. J c reached 0.3 MA cm −2 as measured at 77 K by transport and third-harmonic detection. Those preliminary results confirm the effectiveness of the MOCVD for complex geometries, especially for YBCO deposition on small diameter wires. This approach opens huge perspectives for the elaboration of a new generation of YBCO-based round conductors. (paper)

  3. Nano-engineered pinning centres in YBCO superconducting films

    Energy Technology Data Exchange (ETDEWEB)

    Crisan, A., E-mail: adrian.crisan@infim.ro [National Institute for Materials Physics Bucharest, 105 bis Atomistilor Str., 077125 Magurele (Romania); School of Metallurgy and Materials, University of Birmingham, Edgbaston, B15 2TT Birmingham (United Kingdom); Dang, V.S. [School of Metallurgy and Materials, University of Birmingham, Edgbaston, B15 2TT Birmingham (United Kingdom); Nano and Energy Center, VNU Hanoi University of Science, 334 Nguyen Trai, Thanh Xuan, Hanoi (Viet Nam); Mikheenko, P. [School of Metallurgy and Materials, University of Birmingham, Edgbaston, B15 2TT Birmingham (United Kingdom); Department of Physics, University of Oslo, P.O. Box 1048 Blindern, N-0316 Oslo (Norway)

    2017-02-15

    Highlights: • Power applications of YBCO films/coated conductors in technological relevant magnetic fields requires nano-engineered pinning centre. • Three approaches have been proposed: substrate decoration, quasi-multilayers, and targets with secondary phase nano-inclusions. • Combination of all three approaches greatly increased critical current in YBCO films. • Bulk pinning force, pinning potential, and critical current density are estimated and discussed in relation with the type and strength of pinning centres related to the defects evidenced by Transmission Electron Microscopy. - Abstract: For practical applications of superconducting materials in applied magnetic fields, artificial pinning centres in addition to natural ones are required to oppose the Lorentz force. These pinning centres are actually various types of defects in the superconductor matrix. The pinning centres can be categorised on their dimension (volume, surface or point) and on their character (normal cores or Δκ cores). Different samples have been produced by Pulsed Laser Deposition, with various thicknesses, temperatures and nanostructured additions to the superconducting matrix. They have been characterized by SQUID Magnetic Properties Measurement System and Physical Properties Measurement System, as well as by Transmission Electron Microscopy (TEM). Correlations between pinning architecture, TEM images, and critical currents at various fields and field orientations will be shown for a large number of YBa{sub 2}Cu{sub 3}O{sub x} films with various types and architectures of artificial pinning centres.

  4. Growth of YBCO superconducting thin films on CaF sub 2 buffered silicon

    CERN Document Server

    Bhagwat, S S; Patil, J M; Shirodkar, V S

    2000-01-01

    CaF sub 2 films were grown on silicon using the neutral cluster beam deposition technique. These films were highly crystalline and c-axis oriented. Superconducting YBCO thin films were grown on the Ca F sub 2 buffered silicon using the laser ablation technique. These films showed T sub c (onset) at 90 K and Tc(zero) at 86 K. X-ray diffraction analysis showed that the YBCO films were also oriented along the c-axis.

  5. Plasma-enhanced chemical vapor deposition for YBCO film fabrication of superconducting fault-current limiter

    Energy Technology Data Exchange (ETDEWEB)

    Jun, Byung Hyuk; Kim, Chan Joong

    2006-05-15

    Since the high-temperature superconductor of oxide type was founded, many researches and efforts have been performed for finding its application field. The YBCO superconducting film fabricated on economic metal substrate with uniform critical current density is considered as superconducting fault-current limiter (SFCL). There are physical and chemical processes to fabricate superconductor film, and it is understood that the chemical methods are more economic to deposit large area. Among them, chemical vapor deposition (CVD) is a promising deposition method in obtaining film uniformity. To solve the problems due to the high deposition temperature of thermal CVD, plasma-enhanced chemical vapor deposition (PECVD) is suggested. This report describes the principle and fabrication trend of SFCL, example of YBCO film deposition by PECVD method, and principle of plasma deposition.

  6. In-situ deposition of YBCO high-Tc superconducting thin films by MOCVD and PE-MOCVD

    International Nuclear Information System (INIS)

    Zhao, J.; Noh, D.W.; Chern, C.; Li, Y.Q.; Norris, P.E.; Kear, B.; Gallois, B.

    1991-01-01

    Metal-Organic Chemical Vapor Deposition (MOCVD) offers the advantages of a high degree of compositional control, adaptability for large scale production, and the potential for low temperature fabrication. The capability of operating at high oxygen partial pressure is particularly suitable for in situ formation of high temperature superconducting (HTSC) films. Yttrium barium copper oxide (YBCO) thin films having a sharp zero-resistance transition with T(sub c) greater than 90 K and J(sub c) of approximately 10(exp 4) A on YSZ have been prepared, in situ, at a substrate temperature of about 800 C. Moreover, the ability to form oxide films at low temperature is very desirable for device applications of HTSC materials. Such a process would permit the deposition of high quality HTSC films with a smooth surface on a variety of substrates. Highly c-axis oriented, dense, scratch resistant, superconducting YBCO thin films with mirror-like surfaces have been prepared, in situ, at a reduced substrate temperature as low as 570 C by a remote microwave-plasma enhanced metal-organic chemical vapor deposition (PE-MOCVD) process. Nitrous oxide was used as a reactant gas to generate active oxidizing species. This process, for the first time, allows the formation of YBCO thin films with the orthorhombic superconducting phase in the as-deposited state. The as-deposited films grown by PE-MOCVD show attainment of zero resistance at 72 K with a transition width of about 5 K. MOCVD was carried out in a commercial production scale reactor with the capability of uniform deposition over 100 sq cm per growth run. Preliminary results indicate that PE-MOCVD is a very attractive thin film deposition process for superconducting device technology

  7. Effect of processing conditions and methods on residual stress in CeO2 buffer layers and YBCO superconducting films

    International Nuclear Information System (INIS)

    Xiong Jie; Qin Wenfeng; Cui Xumei; Tao Bowan; Tang Jinlong; Li Yanrong

    2006-01-01

    CeO 2 layers have been fabricated by pulsed laser deposition (PLD) technique on (1 1 0 2) sapphire substrate. Microstructure of CeO 2 layers is characterized by X-ray diffraction as functions of substrate temperature. The effects of the substrate temperature on the residual stress have been studied. The results show that residual stress in CeO 2 film decreased with increasing substrate temperature, not the same development tendency as that of thermal stress. This means that the thermal stress is only a fraction of the residual stress. Moreover, YBCO superconducting films were prepared by direct current (DC) sputtering and pulsed laser deposition (PLD) technique. The residual stress and thermal stress of both YBCO films were measured. PLD processing apparently generated higher intrinsic compressive stresses in comparison to DC sputtering

  8. An all-field-range description of the critical current density in superconducting YBCO films

    International Nuclear Information System (INIS)

    Golovchanskiy, I A; Pan, A V; Shcherbakova, O V; Fedoseev, S A; Dou, S X

    2011-01-01

    A new critical current density (J c ) model for high-quality YBCO (YBa 2 Cu 3 O 7 ) thin films has been proposed, combining thermally activated flux creep with a vortex pinning potential for columnar defects. The pinning for thermally activated vortices has been described as strong pinning on chains of individual edge dislocations that form low-angle domain boundaries in high-quality YBCO thin films. The model yields an adequate description of the J c behaviour over the whole applied field range, as verified by direct measurements of J c in YBCO thin films grown by pulsed-laser deposition. It also indicates that the effective pinning landscape changes under the influence of the external conditions. Remarkably, the pinning potential obtained from the model is consistent with the values obtained for columnar defects, which confirms the validity of the overall approach.

  9. Influence of artificial pinning centers on structural and superconducting properties of thick YBCO films on ABAD-YSZ templates

    Science.gov (United States)

    Pahlke, Patrick; Sieger, Max; Ottolinger, Rick; Lao, Mayraluna; Eisterer, Michael; Meledin, Alexander; Van Tendeloo, Gustaaf; Hänisch, Jens; Holzapfel, Bernhard; Schultz, Ludwig; Nielsch, Kornelius; Hühne, Ruben

    2018-04-01

    Recent efforts in the development of YBa2Cu3O7-x (YBCO) coated conductors are devoted to the increase of the critical current I c in magnetic fields. This is typically realized by growing thicker YBCO layers as well as by the incorporation of artificial pinning centers. We studied the growth of doped YBCO layers with a thickness of up to 7 μm using pulsed laser deposition with a growth rate of about 1.2 nm s-1. Industrially fabricated ion-beam textured YSZ templates based on metal tapes were used as substrates for this study. The incorporation of BaHfO3 (BHO) or Ba2Y(Nb0.5Ta0.5)O6 (BYNTO) secondary phase additions leads to a denser microstructure compared to undoped films. A purely c-axis-oriented YBCO growth is preserved up to a thickness of about 4 μm, whereas misoriented texture components were observed in thicker films. The critical temperature is slightly reduced compared to undoped films and independent of film thickness. The critical current density J c of the BHO- and BYNTO-doped YBCO layers is lower at 77 K and self-field compared to pure YBCO layers; however, I c increases up to a thickness of 5 μm. A comparison between films with a thickness of 1.3 μm revealed that the anisotropy of the critical current density J c(θ) strongly depends on the incorporated pinning centers. Whereas BHO nanorods lead to a strong B∣∣c-axis peak, the overall anisotropy is significantly reduced by the incorporation of BYNTO forming a mixture of short c-axis-oriented nanorods and small (a-b)-oriented platelets. As a result, the J c values of the doped films outperform the undoped samples at higher fields and lower temperatures for most magnetic field directions.

  10. High temperature superconducting YBCO microwave filters

    Science.gov (United States)

    Aghabagheri, S.; Rasti, M.; Mohammadizadeh, M. R.; Kameli, P.; Salamati, H.; Mohammadpour-Aghdam, K.; Faraji-Dana, R.

    2018-06-01

    Epitaxial thin films of YBCO high temperature superconductor are widely used in telecommunication technology such as microwave filter, antenna, coupler and etc., due to their lower surface resistance and lower microwave loss than their normal conductor counterparts. Thin films of YBCO were fabricated by PLD technique on LAO substrate. Transition temperature and width were 88 K and 3 K, respectively. A filter pattern was designed and implemented by wet photolithography method on the films. Characterization of the filter at 77 K has been compared with the simulation results and the results for a made gold filter. Both YBCO and gold filters show high microwave loss. For YBCO filter, the reason may be due to the improper contacts on the feedlines and for gold filter, low thickness of the gold film has caused the loss increased.

  11. Preparation of YBCO on YSZ layers deposited on silicon and sapphire by MOCVD: influence of the intermediate layer on the quality of the superconducting film

    International Nuclear Information System (INIS)

    Garcia, G.; Casado, J.; Llibre, J.; Doudkowski, M.; Santiso, J.; Figueras, A.; Schamm, S.; Dorignac, D.; Grigis, C.; Aguilo, M.

    1995-01-01

    YSZ buffer layers were deposited on silicon and sapphire by MOCVD. The layers deposited on silicon were highly oriented along [100] direction without in-plane orientation, probably because the existence of the SiO 2 amorphous interlayer. In contrast, epitaxial YSZ was obtained on (1-102) sapphire showing an in-plane texture defined by the following relationships: (100) YSZ // (1-102) sapphire and (110) YSZ // (01-12) sapphire. Subsequently, YBCO films were deposited on YSZ by MOCVD. Structural, morphological and electrical characterization of the superconducting layers were correlated with the in-plane texture of the buffer layers. (orig.)

  12. Quality of YBCO thin films grown on LAO substrates exposed to the film deposition - film removal processes

    Energy Technology Data Exchange (ETDEWEB)

    Blagoev, B; Nurgaliev, T [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee, 1784 Sofia (Bulgaria); Mozhaev, P B [Institute of Physics and Technology, Russian Academy of Sciences, 117218 Moscow (Russian Federation); Sardela, M; Donchev, T [Materials Research Laboratory, University of Illinois, 104 South Goodwin Ave., Urbana, IL 61801 (United States)], E-mail: blago_sb@yahoo.com

    2008-05-01

    The characteristics are investigated of high temperature superconducting YBa{sub 2}Cu{sub 3}O{sub 7} (YBCO) films grown on LaAlO{sub 3} (LAO) substrates being exposed a different number of times to YBCO film deposition and acid-solution-based cleaning procedures. Possible mechanisms of degradation of the substrate surface quality reflecting on the growing YBCO film parameters are discussed and analyzed.

  13. Strong Flux Pinning of Nano-Sized Ysz Particles in Ybco Films Prepared by Mod Method

    Science.gov (United States)

    Ye, S.; Suo, H. L.; Liu, M.; Tang, X.; Wu, Z. P.; Zhao, Y.; Zhou, M. L.

    The YBCO films with doped YSZ nanoparticles have been prepared successfully by metal organic doepositon method using trifluoroacetates (TFA-MOD) through dissolving Zr organic salt into the YBCO precursor solution. The doped films have well in-plane and out-plane textures detected by both XRD Φ-scan and ω-scan. The YSZ nanoparticles with the size of about 5 ~ 15 nm were observed on the surface of the YBCO films using both FE-SEM and TEM. By comparing the superconducting properties, it was found that the doped YBCO films had lower Tc than that of undoped YBCO films. However, as increasing the applied magnetic field, Jc of the doped YBCO films were much better than that of undoped one. The Jc was as higher as 2.5 times than that of undoped YBCO film at 77 K and 1 T applied field.

  14. A-axis oriented superconductive YBCO thin films. Growth mechanism on MgO substrate. [Y-Ba-Cu-O

    Energy Technology Data Exchange (ETDEWEB)

    Hamet, J F; Mercey, B; Hervieu, M; Poullain, G; Raveau, B [Centre de Materiaux Supraconducteurs, CRISMAT-ISMRa, 14 - Caen (France)

    1992-08-01

    The growth mechanism of a-axis oriented YBCO thin films has been studied by TEM. At 650degC, a disordered cubic perovskite is first formed with a[sub p]parallela[sub MgO], then a strained tetragonal a-axis oriented perovskite is observed, with c=3a[sub p], slightly misoriented with respect to MgO and showing a marquetry-like contrast. At 750degC, a [1anti 10] axis oriented perovskite is formed whose lattice exhibits a rotation with respect to MgO lattice, but also a tilting of the [CuO[sub 2

  15. Detection of second harmonic of phase dependence of superconducting current in Nb/Au/YBCO heterojunctions

    CERN Document Server

    Komissinskij, F V; Ilichev, E V; Ivanov, Z G

    2001-01-01

    The results of the experimental study on the current phase dependence (CPD) of the heterotransitions, consisting of the niobium and the YBa sub 2 Cu sub 3 O sub x (YBCO) film with an additional interlayer from gold (Nb/Au/YBCO) are presented. The CPD measurement is carried out through the radiofrequency superconducting quantum interferometer. The CPD second harmonic is determined in the Nb/Au/YBCO heterotransitions. Possible causes of its appearance are discussed within the frames of the d +- s combined symmetry of the YBCO order parameter. One of the causes of the CPD second harmonic appearance is the twinning of the YBCO films (001). The second cause of existing the anomalously high critical current consists in the availability of the Nb/Au boundary with the transparence of approx 10 sup - sup 1 in the Nb/Au/YBCO

  16. Excess hall effect in epitaxial YBCO film under moderate magnetic fields, approached by renormalized superconducting fluctuations model

    International Nuclear Information System (INIS)

    Puica, I.; Lang, W.; Goeb, W.; Sobolewski, R.

    2002-01-01

    Full text: Measurements of the Hall effect and the resistivity on precisely-patterned YBCO thin film in moderate magnetic fields B from 0.5 to 6 T oriented parallel to the crystallographic c axis reveal a sign reversal of the Hall coefficient for B < 3 T. The data are confronted with the full quantitative expressions given by the renormalized fluctuation model for the excess Hall conductivity. The model offers a satisfactory quantitative approach to the experimental results, for moderate fields and temperatures near the critical region, provided the inhomogeneity of the critical temperature distribution is also taken into account. For lower fields and temperatures, the adequacy of the model is altered by vortex pinning. (author)

  17. Deposition studies and coordinated characterization of MOCVD YBCO films on IBAD-MgO templates

    International Nuclear Information System (INIS)

    Aytug, T; Paranthaman, M; Heatherly, L; Zuev, Y; Zhang, Y; Kim, K; Goyal, A; Maroni, V A; Chen, Y; Selvamanickam, V

    2009-01-01

    A recently installed research-scale metal-organic chemical vapor deposition (MOCVD) system at Oak Ridge National Laboratory, provided by SuperPower, Inc., has been used to investigate processing variables for MOCVD YBCO precursors and trends in the resulting properties. Systematic studies of YBCO film growth on LaMnO 3 /IBAD-MgO templates were carried out by optimizing deposition temperature and oxygen flow rate. Microstructural and superconducting properties of the YBCO films were analyzed by x-ray diffraction, scanning electron microscopy and transport measurements. The identification of intermediate phases formed during the YBCO precursor transformation was investigated by coordinated reel-to-reel Raman microprobe analysis. With this combination of various characterization techniques, an improved understanding of the growth characteristics of MOCVD YBCO films was established. Finally, critical current densities greater than 2 MA cm -2 for film thicknesses of 0.8 μm were demonstrated.

  18. Deposition studies and coordinated characterization of MOCVD YBCO films on IBAD-MgO templates

    Energy Technology Data Exchange (ETDEWEB)

    Aytug, T; Paranthaman, M [Oak Ridge National Laboratory, Chemical Sciences Division, Oak Ridge, TN 37831 (United States); Heatherly, L; Zuev, Y; Zhang, Y; Kim, K; Goyal, A [Oak Ridge National Laboratory, Materials Science and Technology Division, Oak Ridge, TN 37831 (United States); Maroni, V A [Argonne National Laboratory, Chemical Sciences and Engineering Division, Argonne, IL 60439 (United States); Chen, Y; Selvamanickam, V [SuperPower, Incorporated, 450 Duane Avenue, Schenectady, NY 12304 (United States)], E-mail: aytugt@ornl.gov

    2009-01-15

    A recently installed research-scale metal-organic chemical vapor deposition (MOCVD) system at Oak Ridge National Laboratory, provided by SuperPower, Inc., has been used to investigate processing variables for MOCVD YBCO precursors and trends in the resulting properties. Systematic studies of YBCO film growth on LaMnO{sub 3}/IBAD-MgO templates were carried out by optimizing deposition temperature and oxygen flow rate. Microstructural and superconducting properties of the YBCO films were analyzed by x-ray diffraction, scanning electron microscopy and transport measurements. The identification of intermediate phases formed during the YBCO precursor transformation was investigated by coordinated reel-to-reel Raman microprobe analysis. With this combination of various characterization techniques, an improved understanding of the growth characteristics of MOCVD YBCO films was established. Finally, critical current densities greater than 2 MA cm{sup -2} for film thicknesses of 0.8 {mu}m were demonstrated.

  19. Intermediate Phase Study on YBCO Films Coated by Precursor Solutions With F/Ba Atomic Ratio of 2

    DEFF Research Database (Denmark)

    Wu, W.; Feng, F.; Zhao, Y.

    2016-01-01

    In the chemical solution deposition process of YBCO superconducting films, fluorine is widely regarded to be of significant importance in avoiding the formation of BaCO3, which hinders the growth of high-quality YBCO films. On the other hand, great efforts have been made to decrease the fluorine......) could be routinely obtained on lanthanum aluminate single-crystal substrates....

  20. Evaluation on current-limiting performance of the YBCO thin-film wire considering electric coupling condition

    International Nuclear Information System (INIS)

    Du, H.-I.; Han, B.-S.; Kim, Y.-J.; Lee, D.-H.; Song, S.-S.; Han, T.-H.; Han, S.-C.

    2011-01-01

    The basic way to improve the performance of a superconducting current limiter is to apply and evaluate a superconducting device that is appropriate to the superconducting current limiter. Among the many types of superconducting devices, the YBCO thin film wire has excellent current-limiting performance that is appropriate for actual system application. For the application of the YBCO thin film wire to superconducting current limiters, its current-limiting performance as a unit device must be accurately evaluated, and measures to improve its current-limiting performance must be sought. Accordingly, to evaluate the current-limiting performance of the YBCO thin film wire, this study was conducted to evaluate its resistance-increasing trend, V max , T r , I max , I qt , and current-limiting rate as a unit device, after which the electric coupling condition that consists of a core and windings was used to evaluate the current-limiting performance of the YBCO thin film wire.

  1. Magnetron sputtering of Fe-oxides on the top of HTS YBCO films

    International Nuclear Information System (INIS)

    Nurgaliev, T.; Blagoev, B.; Buchkov, K.; Mateev, E.; Gajda, G.; Nedkov, I.; Kovacheva, D.; Slavov, L.; Starbova, I.; Starbov, N.; Nankovski, M.

    2017-01-01

    The possibilities for preparation of bilayers containing magnetic Fe-oxide (Fe-O) and high temperature superconducting (HTS) YBa 2 Cu 3 O 7−x (YBCO) thin films were investigated. For this purpose, Fe-O films were deposited using reactive magnetron sputtering at comparatively low temperatures T≤250 °C onto dielectric (for example, LaAlO 3 (LAO)) substrates, covered with a HTS YBCO film. The sputtering of the Fe-O layer at such conditions did not lead to a crucial damage of the critical temperature T C of the YBCO film, but could affect the width of the superconducting transition. A decrease of the critical temperature of the (Fe-O)/YBCO/LAO bilayer kept at ambient conditions was observed, possibly due to the negative effects of the water vapour on the sample characteristics. The double peak structure of the imaginary component of the response signal to the AC harmonic magnetic field, observed in such a (Fe-O)/YBCO/LAO sample, was ascribed from two possible views: as a consequence of morphology determined inter- and intra-granular contributions and/or as transitions from dominant irreversible processes as Bean-Livingston barrier to vortex state chains formation. - Highlights: • Iron-oxide (Fe-O) film sputtered on the top of superconducting HTS YBCO film at not very high temperatures. • No crucially damaged superconducting properties of YBCO film during Fe-O sputtering process. • A negative effect of the ambient conditions on the critical temperature of the obtained samples. • A double peak structure of the response signal to the AC harmonic magnetic field in a (Fe-O)/YBCO/LAO is observed.

  2. Magnetron sputtering of Fe-oxides on the top of HTS YBCO films

    Energy Technology Data Exchange (ETDEWEB)

    Nurgaliev, T. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chausse, 1784 Sofia (Bulgaria); Blagoev, B. [Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chausse, 1784 Sofia (Bulgaria); Laboratory of High Magnetic Fields and Low Temperatures, 95 Gajowicka Str., 53-421 Wroclaw (Poland); Buchkov, K. [Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chausse, 1784 Sofia (Bulgaria); Mateev, E. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chausse, 1784 Sofia (Bulgaria); Gajda, G. [Laboratory of High Magnetic Fields and Low Temperatures, 95 Gajowicka Str., 53-421 Wroclaw (Poland); Nedkov, I. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chausse, 1784 Sofia (Bulgaria); Kovacheva, D. [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Street, bl. 10, 1113 Sofia (Bulgaria); Slavov, L. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chausse, 1784 Sofia (Bulgaria); Laboratory of High Magnetic Fields and Low Temperatures, 95 Gajowicka Str., 53-421 Wroclaw (Poland); Starbova, I.; Starbov, N. [Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chausse, 1784 Sofia (Bulgaria); Nankovski, M. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chausse, 1784 Sofia (Bulgaria); Sofia university “St. Kliment Ohridski”, Faculty of Physics, 5 James Bourchier Blvd., 1164 Sofia (Bulgaria)

    2017-05-01

    The possibilities for preparation of bilayers containing magnetic Fe-oxide (Fe-O) and high temperature superconducting (HTS) YBa{sub 2}Cu{sub 3}O{sub 7−x} (YBCO) thin films were investigated. For this purpose, Fe-O films were deposited using reactive magnetron sputtering at comparatively low temperatures T≤250 °C onto dielectric (for example, LaAlO{sub 3} (LAO)) substrates, covered with a HTS YBCO film. The sputtering of the Fe-O layer at such conditions did not lead to a crucial damage of the critical temperature T{sub C} of the YBCO film, but could affect the width of the superconducting transition. A decrease of the critical temperature of the (Fe-O)/YBCO/LAO bilayer kept at ambient conditions was observed, possibly due to the negative effects of the water vapour on the sample characteristics. The double peak structure of the imaginary component of the response signal to the AC harmonic magnetic field, observed in such a (Fe-O)/YBCO/LAO sample, was ascribed from two possible views: as a consequence of morphology determined inter- and intra-granular contributions and/or as transitions from dominant irreversible processes as Bean-Livingston barrier to vortex state chains formation. - Highlights: • Iron-oxide (Fe-O) film sputtered on the top of superconducting HTS YBCO film at not very high temperatures. • No crucially damaged superconducting properties of YBCO film during Fe-O sputtering process. • A negative effect of the ambient conditions on the critical temperature of the obtained samples. • A double peak structure of the response signal to the AC harmonic magnetic field in a (Fe-O)/YBCO/LAO is observed.

  3. Growth and BZO-doping of the nanostructured YBCO thin films on buffered metal substrates

    DEFF Research Database (Denmark)

    Huhtinen, H.; Irjala, M.; Paturi, P.

    2010-01-01

    The growth of the nanostructured YBa2Cu3O6+x (YBCO) films is investigated for the first time on biaxially textured NiW substrates used in coated conductor technology. The optimization process of superconducting layers is made in wide magnetic field and temperature range in order to understand...... the vortex pinning structure and mechanism in our films prepared from nanostructured material. Structural analysis shows that growth mechanism in YBCO films grown on NiW is completely different when compared to YBCO on STO. Films on NiW are much rougher, there is huge in-plane variation of YBCO crystals...... and moreover out-of-plane long range lattice ordering is greatly reduced. Magnetic measurements demonstrate that jc in films grown on NiW is higher in high magnetic fields and low temperatures. This effect is connected to the amount of pinning centres observed in films on metal substrates which are effective...

  4. Chemical solution deposition of YBCO thin film by different polymer additives

    International Nuclear Information System (INIS)

    Wang, W.T.; Li, G.; Pu, M.H.; Sun, R.P.; Zhou, H.M.; Zhang, Y.; Zhang, H.; Yang, Y.; Cheng, C.H.; Zhao, Y.

    2008-01-01

    A polymer-assisted chemical solution deposition approach has been proposed for the preparation of YBCO thin film. Different additives like PVB (polyvinyl butyral), PEG (polyethylene glycol) and PVP (polyvinylpyrrolidone) have been used to adjust the final viscosity of the precursor solution and thus the film formation. In this fluorine-free approach, YBCO has been deposited on single crystal substrates with metal acetates being starting materials. Biaxially textured YBCO thin films have been obtained. However, different additives lead to different microstructure. Dense, smooth and crack-free YBCO film prepared with PVB as additive yields sharp superconducting transition around T c = 90 K as well as high J c (0 T, 77 K) over 3 MA/cm 2

  5. Chemical solution deposition of YBCO thin film by different polymer additives

    Energy Technology Data Exchange (ETDEWEB)

    Wang, W.T.; Li, G.; Pu, M.H.; Sun, R.P.; Zhou, H.M.; Zhang, Y. [Key Laboratory of Magnetic Levitation Technologies and Maglev Trains, Ministry of Education of China, Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu 610031 (China); Zhang, H. [Department of Physics, Peking University, Beijing 100871 (China); Yang, Y. [Key Laboratory of Magnetic Levitation Technologies and Maglev Trains, Ministry of Education of China, Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu 610031 (China); Cheng, C.H. [Key Laboratory of Magnetic Levitation Technologies and Maglev Trains, Ministry of Education of China, Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu 610031 (China); School of Materials Science and Engineering, University of New South Wale, Sydney, 2052 NSW (Australia); Zhao, Y. [Key Laboratory of Magnetic Levitation Technologies and Maglev Trains, Ministry of Education of China, Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu 610031 (China); School of Materials Science and Engineering, University of New South Wale, Sydney, 2052 NSW (Australia)], E-mail: yzhao@swjtu.edu.cn

    2008-09-15

    A polymer-assisted chemical solution deposition approach has been proposed for the preparation of YBCO thin film. Different additives like PVB (polyvinyl butyral), PEG (polyethylene glycol) and PVP (polyvinylpyrrolidone) have been used to adjust the final viscosity of the precursor solution and thus the film formation. In this fluorine-free approach, YBCO has been deposited on single crystal substrates with metal acetates being starting materials. Biaxially textured YBCO thin films have been obtained. However, different additives lead to different microstructure. Dense, smooth and crack-free YBCO film prepared with PVB as additive yields sharp superconducting transition around T{sub c} = 90 K as well as high J{sub c} (0 T, 77 K) over 3 MA/cm{sup 2}.

  6. Structure and oxygen incorporation in low pressure sputtered YBCO films

    International Nuclear Information System (INIS)

    Chaudhary, S.; Pandya, D. K.; Kashyap, S. C.

    2002-01-01

    Thin films of YBa 2 Cu 3 O 7- δ (YBCO) have been successfully grown by reactive RF-magnetron sputtering technique at low pressure. The oxygen partial pressure of 0.95 mTorr, a total pressure (argon and oxygen) of 1.9 mTorr, and a substrate temperature of 775 grad C resulted in good quality films with T C (R=0) = 85.3 K and J Cmag (4.2 K) ≅ 2x10 7 A/cm 2 . The incorporation of oxygen in the as-grown films has been controlled by using different ambient - oxygen, air or argon during in-situ cooling. The superconducting behaviour of the films was studied using resistance-temperature and low field ac-susceptibility measurements and correlated with their structure. All the films exhibited metallic conduction in the normal state. The oxygen- and air- cooled films were superconducting, possessing the usual orthorhombic structure. The argon-cooled films were non-superconducting possessing the tetragonal structure, thus implying that the structure of the film during deposition is tetragonal which transforms to either of the oxygen rich orthorhombic-I or -II phases depending upon the oxygen/air ambient. The 'δ' values of 0.14, 0.32 and 0.70 and higher 'c'-parameters of 1.1785, 1.180 and 1.183 nm have been obtained for oxygen, air and argon cooled films respectively. (Authors)

  7. High quality uniform YBCO film growth by the metalorganic deposition using trifluoroacetates

    Energy Technology Data Exchange (ETDEWEB)

    Wang, S.S., E-mail: wangssh@tsinghua.edu.cn [Key Laboratory of Micro-nano Measurement, Manipulation and Physics (Beihang University), Ministry of Education, Beijing 100191 (China); Beijing Dingchen Superconducting Technology Co., Ltd., Beijing 100084 (China); Zhang, Z.L. [Key Laboratory of Micro-nano Measurement, Manipulation and Physics (Beihang University), Ministry of Education, Beijing 100191 (China); Wang, L. [Applied superconductivity research center, Department of Physics, Tsinghua University, Beijing 100084 (China); Gao, L.K.; Liu, J. [Beijing Dingchen Superconducting Technology Co., Ltd., Beijing 100084 (China)

    2017-03-15

    Highlights: • High quality double-sided YBCO films are fabricated on LaAlO3 substrates by TFA-MOD method with diameters up to 2 in. • Large area YBCO films were very uniform in microstructure and thickness distribution, an average inductive Jc in excess of 6 MA/cm{sup 2} and low R{sub s} (10 GHz) of 0.3 mΩ at 77 K were obtained. • It will greatly promoted the research and applications of large-area YBCO films by chemical solution method. - Abstract: A need exists for the large-area superconducting YBa{sub 2}Cu{sub 3}O{sub 7-x} (YBCO) films with high critical current density for microwave communication and/or electric power applications. Trifluoroacetic metalorganic (TFA-MOD) method is a promising low cost technique for large-scale production of YBCO films, because it does not need high vacuum device and is easily applicable to substrates of various shape and size. In this paper, double-sided YBCO films with maximum 2 in diameter were prepared on LaAlO{sub 3} substrates by TFA-MOD method. Inductive critical current densitiy J{sub c}, microwave surface resistance R{sub s}, as well as the microstructure were characterized. A newly homemade furnace system was used to epitaxially grown YBCO films, which can improve the uniformity of YBCO film significantly by gas supply and temperature distribution proper design. Results showed that the large area YBCO films were very uniform in microstructure and thickness distribution, an average inductive J{sub c} in excess of 6 MA/cm{sup 2} with uniform distribution, and low R{sub s} (10 GHz) below 0.3 mΩ at 77 K were obtained. Andthe film filter may be prepared to work at temperatures lower than 74 K. These results are very close to the highest value of YBCO films made by conventional vacuum method, so we show a very promising route for large-scale production of high quality large-area YBCO superconducting films at a lower cost.

  8. Passivation of Flexible YBCO Superconducting Current Lead With Amorphous SiO2 Layer

    Science.gov (United States)

    Johannes, Daniel; Webber, Robert

    2013-01-01

    across a thermal gradient with as little flow of heat as possible to make an efficient current lead. By protecting YBCO on a flexible substrate of low thermal conductivity with SiO2, a thermally efficient and flexible current lead can be fabricated. The technology is also applicable to current leads for 4 K superconducting electronics current biasing. A commercially available thin-film YBCO composite tape conductor is first stripped of its protective silver coating. It is then mounted on a jig that holds the sample flat and acts as a heat sink. Silicon dioxide is then deposited onto the YBCO to a thickness of about 1 micron using PECVD (plasma-enhanced chemical vapor deposition), without heating the YBCO to the point where degradation occurs. Since SiO2 can have good high-frequency electrical properties, it can be used to coat YBCO cable structures used to feed RF signals across temperature gradients. The prime embodiment concerns the conduction of DC current across the cryogenic temperature gradient. The coating is hard and electrically insulating, but flexible.

  9. Effect of argon addition into oxygen atmosphere on YBCO thin films deposition

    International Nuclear Information System (INIS)

    Mozhaev, P. B.; Borisenko, I. V.; Ovsyannikov, G. A.; Kuehle, A.; Bindslev-Hansen, J.; Johannes, L.; Skov, J. L.

    2002-01-01

    Multicomponent nature of the YBa 2 Cu 3 O x (YBCO) high-temperature superconductor makes difficult fabrication of smooth thin films: every local deviation from stoichiometry can result in seeding of a non-superconducting oxide particle. High density of such particles on typical YBCO thin film surface, however, presumes overall non-stoichiometry of the film. Such an effect can result from (i) non-uniform material transport from target to substrate, and (ii) re-evaporation or re-sputtering from the growing film surface. The first reason is more usual for laser ablation deposition technique, the second is typical for long sputtering deposition processes. Substitution of oxygen with argon in the deposition atmosphere improves surface quality of YBCO thin films deposited both by laser ablation and DC-sputtering at high pressure techniques. In the first case, the ablated species are scattered different ways in the oxygen atmosphere. Addition of argon decreases the inelastic scattering of barium; the proper part of Ar in the deposition atmosphere makes scattering and, hence, transport of all atoms uniform. The YBCO films deposited by DC-sputtering at high pressure technique are Ba-deficient also, but the reason is re-sputtering of Ba from the growing film as a result of negative oxygen ions bombardment. Such bombardment can lead also to chemical interaction of the deposited material with the substrate, as in the case of deposition of YBCO thin film on the CeO 2 buffer layer on sapphire. Substitution of oxygen with argon not only suppresses ion bombardment of the film, but also increases discharge stability due to presence of positive Ar + ions. The limiting factor of argon substitution is sufficient oxygenation of the growing oxide film. When oxygen partial pressure is too small, the superconducting quality of the YBCO thin film decreases and such a decrease cannot be overcome by prolonged oxygenation after deposition. (Authors)

  10. State of the art and prospective of large scale applications of YBCO thick films grown on metallic substrates

    International Nuclear Information System (INIS)

    Boffa, Vincenzo

    1997-09-01

    In the framework of the high temperature superconducting materials, YBa 2 Cu 3 O 7 (YBCO) shows very interesting intrinsic superconducting transport properties at temperature higher than the liquid nitrogen temperature. These properties are very important in large scale applications: transport of energy, magnets, transformers, etc. Unfortunately the potential of this material cannot be achieved today, since it is very difficult to manufacture YBCO based tapes or cables. In the last years several groups have tried to overcome the problems with new fabrication techniques. In the present report the state of the art and the prospective in the field of YBCO film fabrication on metallic substrates are presented

  11. Magnetic response of superconducting mesoscopic-size YBCO powder

    Energy Technology Data Exchange (ETDEWEB)

    Deimling, C.V. [Grupo de Supercondutividade e Magnetismo, Departamento de Fisica, Universidade Federal de Sao Carlos, Sao Carlos, SP (Brazil)], E-mail: cesard@df.ufscar.br; Motta, M.; Lisboa-Filho, P.N. [Laboratorio de Materiais Supercondutores, Departamento de Fisica, Universidade Estadual Paulista, Bauru, SP Brazil (Brazil); Ortiz, W.A. [Grupo de Supercondutividade e Magnetismo, Departamento de Fisica, Universidade Federal de Sao Carlos, Sao Carlos, SP (Brazil)

    2008-07-15

    In this work it is reported the magnetic behavior of submicron and mesoscopic-size superconducting YBCO powders, prepared by a modified polymeric precursors method. The grain size and microstructure were analyzed using scanning electron microscopy (SEM). Measurements of magnetization and AC-susceptibility as a function of temperature were performed with a quantum design SQUID magnetometer. Our results indicated significant differences on the magnetic propreties, in connection with the calcination temperature and the pressure used to pelletize the samples. This contribution is part of an effort to study vortex dynamics and magnetic properties of submicron and mesoscopic-size superconducting samples.

  12. Surface resistances of 5-cm-diameter YBCO films prepared by MOD for microwave applications

    International Nuclear Information System (INIS)

    Manabe, T.; Sohma, M.; Yamaguchi, I.; Tsukada, K.; Kondo, W.; Kamiya, K.; Tsuchiya, T.; Mizuta, S.; Kumagai, T.

    2006-01-01

    Large-area high-T c superconducting films with low surface resistances R s are required for use in microwave applications such as band pass filters. In this paper, preparation of 5-cm-diameter YBCO films on LaAlO 3 (LAO) and CeO 2 -buffered sapphire (CbS) substrates by metalorganic deposition (MOD) using a fluorine-free coating solution and their superconducting properties are described. The optimum firing conditions for YBCO films greatly depend on the substrate materials; a heating rate at ramp as high as 200 deg. C /min is necessary for films on LAO whereas a lower heating rate, e.g., 20 deg. C /min, is required for films on CbS. Accordingly, the suitable furnace systems for these substrates have been varied. As a result, a YBCO film with high J c (77 K) of 2.7 MA/cm 2 and a low R s (12 GHz, 77 K) of 0.54 mΩ was prepared on LAO by using an infrared image furnace. On the other hand, a YBCO film with a higher J c (77 K) of 4.0 MA/cm 2 and the same R s (12 GHz, 77 K) of 0.54 mΩ was prepared on CbS by using a tube furnace

  13. Influence of interface reactions on the YBCO films grown by fluorine-free solution route

    DEFF Research Database (Denmark)

    Zhao, Yue; Wu, Wei; Tang, Xiao

    2015-01-01

    Fabrication of full-stacked coated conductors by all-chemical-solution routes exhibit a great potential in view of further reducing the cost and increasing the throughput for industrialization. Growth of YBa2Cu3O7−x (YBCO) superconducting films by fluorine-free metal organic deposition routes (FF......-MOD) which are environmental friendly has attracted more attentions recently. In this work, comparison study was performed on the YBCO-Ag superconducting thin films deposited on two types of single crystal substrates, LaAlO3 and Ce0.9La0.9O2−y/YSZ. The structural characterization and superconducting...... properties studies reveal that the interface reactions between the YBCO-Ag film and the CLO cap layer play an essential role on the nucleation and growth of YBCO-Ag films from the FF solution. Weak texture caused by serious interface reactions at high growth temperature is the main explanations for the poor...

  14. Synthesis and characterization of superconducting YBCO powder

    International Nuclear Information System (INIS)

    Praveen, B.; Karki, T.; Krishnamoorthi, J.

    2008-01-01

    Full text: Superconducting yttrium barium copper oxide power has been synthesized through solid state sintering method - milling and sintering - using Y 2 O 3 , BaCo 3 and CuO powders. XRD result of the milled and sintered powder reveals that the powder that has formed contains YBa 2 Cu 3 O 6.5 superconducting phase. Results obtained by SEM/EDAX show the distribution of the different elements. Experiments carried out by intermediate firing and final annealing in oxygen controlled atmosphere show the diffusion of oxygen in preformed YBa 2 Cu 3 O 6.5 and their results are discussed

  15. Flux pinning in MOD YBCO films by chemical doping

    International Nuclear Information System (INIS)

    Zhou, Y X; Ghalsasi, S; Rusakova, I; Salama, K

    2007-01-01

    A novel nanomaterial synthesis technique has been developed to introduce 0D (particles), 1D (columnar defects) and 3D (domains) nanoscale pinning centres in MOD Y 1 Ba 2 Cu 3 O 7 (YBCO) coated conductors. We have succeeded in introducing nanoscale Y enriched particles, nanoscale 90 0 rotated Y 1/3 Sm 2/3 Ba 2 Cu 3 O 7 domains and nanoscale Zr enriched columnar defects into YBCO layers by different chemical doping. The pinning force density in Y 2 O 3 -doped YBCO film is found to be larger than that of pure YBCO film at all fields. Also it was found that YBCO films with Sm substituting for Y have yielded improved critical current density characteristics over a wide range of magnetic fields. Maximum pinning force densities exceeding 7 and 8 GN m -3 are obtained in 5% BZO-doped and Sm substituted YBCO films, respectively. Additionally, TEM studies revealed nanoscale Zr enriched columnar defects distributing in the matrix of the c-oriented YBCO film throughout the whole cross section. This indicates that chemical doping is a promising fabrication technique to create specific pinning landscapes in YBCO coated conductors

  16. Preparing superconducting nanopowder based YBCO/Ag tapes

    DEFF Research Database (Denmark)

    Paturi, P.; Raittila, J.; Grivel, J.C.

    2002-01-01

    YBCO nanopowder consisting of 1-3 nm thick and 40 nm wide particles has been used to make silver clad superconducting tapes. After annealing in nitrogen at 945 degreesC for 10 h a critical current of 5.02 A (3300 A/cm(2)) was attained, Annealing in mixed atmosphere of oxygen and nitrogen was also...... carried out and this procedure produced tapes with a critical current of 2.83 A (2200 A/cm(2)). These tapes show very good characteristics in magnetic fields. (C) 2002 Elsevier Science B.V. All rights reserved....

  17. Low energy electron beam processing of YBCO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Chromik, Š., E-mail: stefan.chromik@savba.sk [Institute of Electrical Engineering, SAS, Dúbravská cesta 9, 841 04 Bratislava (Slovakia); Camerlingo, C. [CNR-SPIN, Istituto Superconduttori, Materiali Innovativi e Dispositivi, via Campi Flegrei 34, 80078 Pozzuoli (Italy); Sojková, M.; Štrbík, V.; Talacko, M. [Institute of Electrical Engineering, SAS, Dúbravská cesta 9, 841 04 Bratislava (Slovakia); Malka, I.; Bar, I.; Bareli, G. [Department of Physics, Ben Gurion University of the Negev, P.O.B. 653, 84105 Beer Sheva (Israel); Jung, G. [Department of Physics, Ben Gurion University of the Negev, P.O.B. 653, 84105 Beer Sheva (Israel); Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw (Poland)

    2017-02-15

    Highlights: • Improvement of superconducting properties of irradiated bridges under certain conditions. • 30 keV irradiation influence CuO{sub 2} planes as well as oxygen chains. • Direct confirmation of changes in oxygen chains using micro-Raman spectroscopy. • Possibility of electron writing. - Abstract: Effects of low energy 30 keV electron irradiation of superconducting YBa{sub 2}Cu{sub 3}O{sub 7−δ} thin films have been investigated by means of transport and micro-Raman spectroscopy measurements. The critical temperature and the critical current of 200 nm thick films initially increase with increasing fluency of the electron irradiation, reach the maximum at fluency 3 − 4 × 10{sup 20} electrons/cm{sup 2}, and then decrease with further fluency increase. In much thinner films (75 nm), the critical temperature increases while the critical current decreases after low energy electron irradiation with fluencies below 10{sup 20} electrons/cm{sup 2}. The Raman investigations suggest that critical temperature increase in irradiated films is due to healing of broken Cu−O chains that results in increased carrier’s concentration in superconducting CuO{sub 2} planes. Changes in the critical current are controlled by changes in the density of oxygen vacancies acting as effective pinning centers for flux vortices. The effects of low energy electron irradiation of YBCO turned out to result from a subtle balance of many processes involving oxygen removal, both by thermal activation and kick-off processes, and ordering of chains environment by incident electrons.

  18. Pulsed-laser-deposited YBCO thin films using modified MTG processed targets

    CERN Document Server

    Kim, C H; Kim, I T; Hahn, T S

    1999-01-01

    YBCO thin films were deposited by pulsed laser deposition from targets fabricated using the modified melt-textured growth (MTG) method and the solid-state sintering (SSS) method. All of the films showed c-axis orientations, but the films from the MTG targets had better crystallinity than those from the SSS targets. As the substrate temperature was increased, T sub c and J sub c of the films increased. The films from the MTG targets showed better superconducting properties than those from the SSS targets. From the composition analysis of the targets, the Y-richer vapor species arriving at the substrate from the MTG targets are thought to form a thermodynamically more stable YBCO phase with less cation disorder.

  19. Flux flow and flux creep in thick films of YBCO. [Y-Ba-Cu-O

    Energy Technology Data Exchange (ETDEWEB)

    Rickets, J.; Vinen, W.F.; Abell, J.S.; Shields, T.C. (Superconductivity Research Group, Univ. of Birmingham (United Kingdom))

    1991-12-01

    The results are described of new experiments designed to study flux creep and flux flow along a single flux percolation path in thick films of YBCO. The flux flow regime is studied by a four-point resistive technique using pulsed currents, and the flux creep regime by observing the rate at which flux enters a superconducting loop in parallel with the resistance that is associated with the flux percolation path. (orig.).

  20. Quench and recovery characteristics of Au/YBCO thin film type SFCL

    International Nuclear Information System (INIS)

    Yim, S.-W.; Kim, H.-R.; Hyun, O.-B.; Sim, J.

    2007-01-01

    Although, a superconducting fault current limiter (SFCL) guarantees the fast limiting operation, it usually needs a considerably long time to recover to superconducting state after the quench. Considering the reclosing time in the protection coordination of power systems, the time required for the recovery should be investigated clearly. In this study, the quench and recovery characteristics of Au/YBCO thin films designed as an SFCL element with a bi-spiral pattern were investigated. The quench development of the SFCL was measured by two kinds of methods. Firstly, after applying the fault current of 5.5 cycles, we measured the resistance of the YBCO by a small current flowing through the pattern of Au/YBCO thin film. The temperature variation above the critical temperature, 85 K, was investigated indirectly from the resistance variation. Secondly, in order to measure the temperature from 85 K to 77 K, a meander line shape of Au thin film was evaporated on the back side and used as a temperature detecting sensor. The temperature variations detected by both methods were compared and analyzed. For the investigation of the recovery characteristics, the required time for the recovery of the superconductivity was measured for various magnitude and duration of the applied voltages. In addition, for the purpose of examining the dependence of the line impedance on the recovery time, resistors of various resistances were inserted in the fault current testing circuit and the recovery time was measured and analyzed

  1. Distribution analysis of thermal effusivity for sub-micrometer YBCO thin films using thermal microscope

    International Nuclear Information System (INIS)

    Yagi, T.; Taketoshi, N.; Kato, H.

    2004-01-01

    Thermal effusivity measurements have been carried out for sub-micrometer YBCO superconducting films using thermal microscope based upon thermoreflectance technique. Two samples were prepared: c-axis aligned YBCO thin films with 800 nm in thickness synthesized on MgO and SrTiO 3 substrates. Measured thermal effusivities perpendicular to the surface, i.e. in parallel with c-axis were determined to be 1770 J/m 2 s 0.5 K on MgO substrate and 1420 J/m 2 s 0.5 K for that on SrTiO 3 substrate, respectively. The scatter of the measurements is estimated to be lower than ±5.2%. These values are consistent with reported values of YBCO single crystal in the direction of c-axis. In addition, 2D profiling image, that is, in-plane distribution of thermal effusivity was well obtained for the YBCO film on MgO substrate by operating this thermal microscope in a scanning mode. Its standard deviation of the in-plane thermal effusivity scattering due to the non-uniformity is evaluated to be ±5.7%

  2. Characteristics of the electrical response of YBCO films with different morphologies to optical irradiation

    International Nuclear Information System (INIS)

    Frack, E.K.; Madhavrao, L.; Patl, R.; Drake, R.E.; Radparvar, M.

    1991-01-01

    The authors have fabricated YBCO films of varying thicknesses (300 Angstrom - 3000 Angstrom) and morphologies, and measured their electrical response to optical radiation. This paper reports on these measurements, emphasizing the dependence on temperature, light chopping frequency, and cryogenic environment. The temperature dependence of the film resistance is determined in part by the film morphology. This morphology may be represented by a simple model consisting of a two-dimensional array of coupled grains. The magnitude of the bolometric response correlates as expected with the sharpness of the superconducting transition. The increased response observed at lower temperatures (non-equilibrium) correlates with the temperature dependence of the resistance above the transition

  3. Growth rate of YBCO-Ag superconducting single grains

    Science.gov (United States)

    Congreve, J. V. J.; Shi, Y. H.; Dennis, A. R.; Durrell, J. H.; Cardwell, D. A.

    2017-12-01

    The large scale use of (RE)Ba2Cu3O7 bulk superconductors, where RE=Y, Gd, Sm, is, in part, limited by the relatively poor mechanical properties of these inherently brittle ceramic materials. It is reported that alloying of (RE)Ba2Cu3O7 with silver enables a significant improvement in the mechanical strength of bulk, single grain samples without any detrimental effect on their superconducting properties. However, due to the complexity and number of inter-related variables involved in the top seeded melt growth (TSMG) process, the growth of large single grains is difficult and the addition of silver makes it even more difficult to achieve successful growth reliably. The key processing variables in the TSMG process include the times and temperatures of the stages within the heating profile, which can be derived from the growth rate during the growth process. To date, the growth rate of the YBa2Cu3O7-Ag system has not been reported in detail and it is this lacuna that we have sought to address. In this work we measure the growth rate of the YBCO-Ag system using a method based on continuous cooling and isothermal holding (CCIH). We have determined the growth rate by measuring the side length of the crystallised region for a number of samples for specified isothermal hold temperatures and periods. This has enabled the growth rate to be modelled and from this an optimized heating profile for the successful growth of YBCO-Ag single grains to be derived.

  4. State of the art and prospective of large scale applications of YBCO thick films grown on metallic substrates; Possibilita` applicative a larga scala dei film spessi di YBCO su substrati metallici: Stato dell`arte e prospettive

    Energy Technology Data Exchange (ETDEWEB)

    Boffa, Vincenzo [ENEA, Centro Ricerche Frascati, Rome (Italy). Dipt. Energia

    1997-09-01

    In the framework of the high temperature superconducting materials, YBa{sub 2}Cu{sub 3}O{sub 7} (YBCO) shows very interesting intrinsic superconducting transport properties at temperature higher than the liquid nitrogen temperature. These properties are very important in large scale applications: transport of energy, magnets, transformers, etc. Unfortunately the potential of this material cannot be achieved today, since it is very difficult to manufacture YBCO based tapes or cables. In the last years several groups have tried to overcome the problems with new fabrication techniques. In the present report the state of the art and the prospective in the field of YBCO film fabrication on metallic substrates are presented.

  5. Vortex pinning landscape in MOD-TFA YBCO nanostroctured films

    Science.gov (United States)

    Gutierrez, J.; Puig, T.; Pomar, A.; Obradors, X.

    2008-03-01

    A methodology of general validity to study vortex pinning in YBCO based on Jc transport measurements is described. It permits to identify, separate and quantify three basic vortex pinning contributions associated to anisotropic-strong, isotropic-strong and isotropic-weak pinning centers. Thereof, the corresponding vortex pinning phase diagrams are built up. This methodology is applied to the new solution-derived YBCO nanostructured films, including controlled interfacial pinning by the growth of nanostructured templates by means of self-assembled processes [1] and YBCO-BaZrO3 nanocomposites prepared by modified solution precursors. The application of the methodology and comparison with a standard solution-derived YBCO film [2], enables us to identify the nature and the effect of the additional pinning centers induced. The nanostructured templates films show c-axis pinning strongly increased, controlling most of the pinning phase diagram. On the other hand, the nanocomposites have achieved so far, the highest pinning properties in HTc-superconductors [3], being the isotropic-strong defects contribution the origin of their unique properties. [1] M. Gibert et al, Adv. Mat. vol 19, p. 3937 (2007) [2] Puig.T et al, SuST EUCAS 2007 (to be published) [3] J. Gutierrez et al, Nat. Mat. vol. 6, p. 367 (2007) * Work supported by HIPERCHEM, NANOARTIS and MAT2005-02047

  6. Raman spectra, microstructure and superconducting properties of Sb(III)-YBCO composite superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Elsabawy, Khaled M. [Chemistry Department, Faculty of Science, Tanta University, Tanta (Egypt)]. E-mail: ksabawy@yahoo.com

    2005-11-15

    The pure YBCO (YBa{sub 2}Cu{sub 3}O{sub 7}) and its variant antimony containing composites with general formula; Y{sub 1+x}Sb {sub x}Ba{sub 2}Cu{sub 3}O {sub z}, where x = 0.1, 0.2, 0.4 and 0.6 mol%, respectively, were prepared by the solid-state reaction route. X-ray measurements indicated that Sb{sup 3+} ions have a negligible effect on the main crystalline structure and substitutes Y-sites successfully in lattice structure of 123-YBCO at low concentrations of doping (x = 0.1 {sup {yields}} 0.2). From SE-microscopy mapping and EDX elemental analysis, Sb{sup 3+} was detected qualitatively with good approximation to the actual molar ratio but not observed at 123-YBCO grain boundaries which confirm that antimony (III) has diffused regularly into material bulk of superconducting 123-YBCO-phase at low concentrations. Additions of Sb(III) affected sharply on the main vibrating modes of YBCO regime particularly, on the apical oxygen (O{sub 4}) vibrational mode A {sub 1g}. Magnetic susceptibility measurements proved that antimony oxide additions have slight effect on the transport properties of YBCO-composites regime.

  7. Improving superconducting properties of YBCO high temperature superconductor by Graphene Oxide doping

    Energy Technology Data Exchange (ETDEWEB)

    Dadras, S., E-mail: dadras@alzahra.ac.ir; Dehghani, S.; Davoudiniya, M.; Falahati, S.

    2017-06-01

    In this research, we report the synthesis and characterization of YBa{sub 2}Cu{sub 3}O{sub 7-δ} (YBCO) high temperature superconductor prepared by sol-gel method and doped with Graphene Oxide (GO) in different weight percentages, 0, 0.1, 0.7 and 1 % wt. The x-ray diffraction (XRD) analysis confirms the formation of orthorhombic phase of superconductivity for all the prepared samples. We found that GO doping reduces the crystalline size of the samples. We evaluated the effects of GO doping on the normal state resistivity (ρ), superconducting transition temperature (T{sub c}) and critical current density (J{sub c}). The results show that the GO doping has a positive effect on these properties. Also, the highest J{sub c} is obtained for the 0.7 %wt GO doped YBCO compound that its critical current density is about 15 times more than the J{sub c} of pure one in 0.4 T magnetic field. The scanning electron microscope (SEM) analysis shows that there are better connections between the grains of GO doped samples. - Highlights: • Graphene Oxide doping increased the YBCO critical current density. • Graphene Oxide creates a better connection between the YBCO grains. • The normal resistivity of samples were decreased by GO doping to YBCO compounds. • Graphene Oxide doping has a positive effect on the critical transition temperature.

  8. Critical current survival in the YBCO superconducting layer of a delaminated coated conductor

    Science.gov (United States)

    Feng, Feng; Fu, Qishu; Qu, Timing; Mu, Hui; Gu, Chen; Yue, Yubin; Wang, Linli; Yang, Zhirong; Han, Zhenghe; Feng, Pingfa

    2018-04-01

    A high-temperature superconducting coated conductor can be practically applied in electric equipment due to its favorable mechanical properties and critical current (I c) performance. However, the coated conductor can easily delaminate because of its poor stress tolerance along the thickness direction. It would be interesting to investigate whether the I c of the delaminated YBa2Cu3O7-δ (YBCO) layer can be preserved. In this study, coated conductor samples manufactured through the metal organic deposition route were delaminated by liquid nitrogen immersion. Delaminated samples, including the YBCO layer and silver stabilizer, were obtained. Delamination occurred inside the YBCO layer and near the YBCO-CeO2 interface, as suggested by the results of scanning electron microscopy (SEM) and x-ray diffraction. A scanning Hall probe system was employed to measure the I c distribution of the original sample and the delaminated sample. It was found that approximately 50% of the I c can be preserved after delamination, which was verified by I c measurements using the four-probe method. Dense and crack-free morphologies of the delaminated surfaces were observed by SEM, which accounts for the I c survival of the delaminated YBCO layer. The potential application of the delaminated sample in superconducting joints was discussed based on the oxygen diffusion estimation.

  9. Ag induced suppression of irradiation response in YBCO/Ag composite thin films

    International Nuclear Information System (INIS)

    Behera, D.; Mohanty, T.; Mohanta, D.; Patnaik, K.; Mishra, N.C.; Senapati, L.; Kanjilal, D.; Mehta, G.K.; Pinto, R.

    1999-01-01

    Practical application of cuprate superconductors in radiation environment demands that these systems remain insensitive to the irradiation induced defects. The cuprate superconductors however are many orders of magnitude more sensitive than the conventional low T c superconductors. To suppress the irradiation sensitivity of cuprates we consider a crystal engineering approach where metal ions as Ag is made to occupy inter and intra-granular sites of YBa 2 Cu 3 O 7 thin films. We show that superconducting and normal state properties of YBCO/Ag composite thin films prepared by laser ablation remain unchanged under 140 MeV Si ion irradiation up to fluence of 8 x 10 14 ions/cm 2 . The inter- and intra-granular occupancy of Ag is shown to induce microstructural modifications and rigidity to the CuO chains respectively which in turn lead to the radiation insensitivity of the composite films. (author)

  10. Flux pinning characteristics of Sn-doped YBCO film by the MOD process

    International Nuclear Information System (INIS)

    Choi, S.M.; Shin, G.M.; Yoo, S.I.

    2013-01-01

    Highlights: ► The pinning effects of undoped and Sn-doped YBCO films by MOD were characterized. ► Sn-containing nanoparticles were trapped in Sn-doped YBCO films by MOD. ► Sn-containing nanoparticles were identified as the YBa 2 SnO 5.5 (YBSO) phase by TEM. ► The YBSO nanoparticles are responsible for improved flux pinning effect. ► We report the orientation relationship between YBSO nanoparticles and YBCO matrix. -- Abstract: Compared with the undoped YBa 2 Cu 3 O 7−δ (YBCO) film, 10 mol% Sn-doped YBCO film exhibited significantly enhanced critical current densities (J c ) in magnetic fields up to 5 T at 65 and 77 K for H//c, indicating that the Sn-doped YBCO film possesses more effective flux pinning centers. Both samples were grown on the SrTiO 3 (STO) (1 0 0) single crystal substrates by the metal-organic deposition (MOD) process. Larger J c (77 K, 1 T) values of Sn-doped YBCO film are observed over a wide field-orientation angle (θ) except the field-orientations close to the ab-plane of YBCO (85° c values for 85° 2 SnO 5.5 (YBSO) phase by STEM (scanning transmission electron microscopy)-EDS (energy dispersive X-ray spectroscopy) analysis. Further analyses by HR-TEM (high resolution-transmission electron microscopy) revealed that YBSO nanoparticles completely surrounded by the YBCO matrix had random orientation with YBCO while those located at the interface of YBCO/STO substrate had epitaxial relationship with YBCO

  11. Tunable pinning effects produced by non-uniform antidot arrays in YBCO thin films

    Energy Technology Data Exchange (ETDEWEB)

    George, J.; Jones, A.; Al-Qurainy, M. [Institute for Superconducting and Electronic Materials, University of Wollongong, NSW (Australia); Fedoseev, S.A. [Institute for Superconducting and Electronic Materials, University of Wollongong, NSW (Australia); Centre for Medical Radiation Physics, University of Wollongong, NSW (Australia); Rosenfeld, A. [Centre for Medical Radiation Physics, University of Wollongong, NSW (Australia); Pan, A.V. [Institute for Superconducting and Electronic Materials, University of Wollongong, NSW (Australia); National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow (Russian Federation)

    2017-04-15

    Uniform, graded and spaced arrays of 3 μm triangular antidots in pulsed laser deposited YBa{sub 2}Cu{sub 3}O{sub 7} (YBCO) superconducting thin films are compared by examining the improvements in the critical current density J{sub c} they produced. The comparison is made to establish the role of their lithographically defined (non-)uniformity and the effectiveness to control and/or enhance the critical current density. It is found that almost all types of non-uniform arrays, including graded ones enhance J{sub c} over the broad applied magnetic field and temperature range due to the modified critical state. Whereas uniform arrays of antidots either reduce or produce no effect on J{sub c} compared to the original (as-deposited) thin films. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Numerical analysis of the influence of buffer layer thickness on the residual stresses in YBCO/La2Zr2O7/Ni superconducting materials

    International Nuclear Information System (INIS)

    Celik, Erdal; Sayman, Onur; Karakuzu, Ramazan; Ozman, Yilmaz

    2007-01-01

    The present paper addresses a numerical investigation of the influence of buffer layer thickness on the residual stress in YBCO/La 2 Zr 2 O 7 /Ni architectured materials under cryogenic conditions by using classical lamination theory (CLT) and finite element method (FEM) for coated conductor applications. YBCO/La 2 Zr 2 O 7 multilayer films were fabricated on Ni tape substrate using reel-to-reel sol-gel and pulse laser deposition (PLD) systems. The microstructural evolution of high temperature superconducting YBCO film and buffer layers with La 2 Zr 2 O 7 configuration grown on textured Ni tape substrates was investigated by using a scanning electron microscope (SEM). Thermal stress analysis of YBCO/La 2 Zr 2 O 7 /Ni multilayer sample was performed by using CLT in the temperature range of 298-175 K in liquid helium media. The YBCO/La 2 Zr 2 O 7 /Ni sample strip was solved by using FEM for linear or nonlinear cases in the temperature range of 298-3 K in liquid helium media. SEM observations revealed that crack-free, pinhole-free, continuous superconducting film and buffer layer were obtained by sol-gel and PLD systems. In addition to microstructural observations, it was found that the largest compressive stresses and failure occur in La 2 Zr 2 O 7 buffer layer due to its smallest thermal expansion coefficient. The thickness of La 2 Zr 2 O 7 buffer layer affects the failure. The stress component of σ x is the smallest in Ni tape substrate due to its largest thickness

  13. Superconducting fault current limiter using high-resistive YBCO tapes

    Energy Technology Data Exchange (ETDEWEB)

    Yazawa, T. [Power and Industrial System R and D Center, Toshiba Corporation, 2-4 Suehiro, Tsurumi, Yokohama 230-0045 (Japan)], E-mail: takashi.yazawa@toshiba.co.jp; Koyanagi, K.; Takahashi, M.; Ono, M.; Toba, K.; Takigami, H.; Urata, M. [Power and Industrial System R and D Center, Toshiba Corporation, 2-4 Suehiro, Tsurumi, Yokohama 230-0045 (Japan); Iijima, Y.; Saito, T. [Fujikura Ltd., 1-5-1 Kiba, Koto, Tokyo 135-0042 (Japan); Ameniya, N. [Yokohama National University, 79-1 Tokiwadai, Hodogaya, Yokohama 240-8501 (Japan); Shiohara, Y. [Superconductivity Research Laboratory, ISTEC, 1-10-13 Shinonome, Koto, Tokyo 135-0062 (Japan)

    2008-09-15

    One of the programs in the Ministry of Economy and Trade and Industry (METI) project regarding R and D on YBCO conductor is to evaluate the applicability of the developed conductor toward several applications. This paper focuses on a fault current limiter (FCL) as one of the expected power applications. YBCO tape conductors with ion beam assisted deposition (IBAD) substrate are used in this work. In order to obtain high resistance of the conductor, which is preferable to an FCL, the thickness of the protecting layer made of silver was decreased as possible. Then high-resistive metal stabilizing layer is attached on the silver layer to improve stability. Obtaining the relevant current limiting performance on short sample experiments, model coils were developed to aim the 6.6 kV-class FCL. Short circuit experiments were implemented with a short circuit generator. The coil successfully restricted the short circuit current over 17 kA to about 700 A by the applied voltage of 3.8 kV, which is nominal phase-to-ground voltage. The experimental results show good agreement with computer analyses and show promising toward the application.

  14. Preparation and structural properties of YBCO films grown on GaN/c-sapphire hexagonal substrate

    Energy Technology Data Exchange (ETDEWEB)

    Chromik, S., E-mail: stefan.chromik@savba.sk [Institute of Electrical Engineering, SAS, Dubravska cesta 9, 84104 Bratislava (Slovakia); Gierlowski, P. [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Spankova, M.; Dobrocka, E.; Vavra, I.; Strbik, V.; Lalinsky, T.; Sojkova, M. [Institute of Electrical Engineering, SAS, Dubravska cesta 9, 84104 Bratislava (Slovakia); Liday, J.; Vogrincic, P. [Department of Microelectronics, Slovak Technical University, Ilkovicova 3, 81219 Bratislava (Slovakia); Espinos, J.P. [Instituto de Ciencia de Materiales de Sevilla, Avda Americo Vespucio 49, 41092 Sevilla (Spain)

    2010-07-01

    Epitaxial YBCO thin films have been grown on hexagonal GaN/c-sapphire substrates using DC magnetron sputtering and pulsed laser deposition. An MgO buffer layer has been inserted between the substrate and the YBCO film as a diffusion barrier. X-ray diffraction analysis indicates a c-axis oriented growth of the YBCO films. {Phi}-scan shows surprisingly twelve maxima. Transmission electron microscopy analyses confirm an epitaxial growth of the YBCO blocks with a superposition of three a-b YBCO planes rotated by 120 deg. to each other. Auger electron spectroscopy and X-ray photoelectron spectroscopy reveal no surface contamination with Ga even if a maximum substrate temperature of 700 deg. C is applied.

  15. Superconducting Electronic Film Structures

    Science.gov (United States)

    1991-02-14

    Segmuller, A., Cooper, E.I., Chisholm, M.F., Gupta, A. Shinde, S., and Laibowitz, R.B. Lanthanum gallate substrates for epitaxial high-T superconducting thin...M. F. Chisholm, A. Gupta, S. Shinde, and R. B. Laibowitz, " Lanthanum Gallate Substrates for Epitaxial High-T c Superconducting Thin Films," Appl...G. Forrester and J. Talvacchio, " Lanthanum Copper Oxide Buffer Layers for Growth of High-T c Superconductor Films," Disclosure No. RDS 90-065, filed

  16. Planar intrinsic Josephson junctions with in-plane aligned YBCO films

    CERN Document Server

    Zhang, L; Kobayashi, T; Goto, T; Mukaida, M

    2002-01-01

    Planar type devices were fabricated by patterning in-plane aligned YBa sub 2 Cu sub 3 O sub 7 sub - subdelta (YBCO) films. The current-voltage characteristics along the c-axis at various temperatures and oxygen contents were measured. The current voltage curves showing supercurrent and hysteresis were obtained for the samples annealed at an oxygen pressure of 1.3 x 10 sup 4 Pa, while the supercurrent and hysteresis became smaller and even disappeared as the oxygen pressure decreased. The relationships between the critical currents and temperatures are similar to those of d-wave superconducting tunnel junctions. These results indicate the formation of stacks of intrinsic Josephson junctions, which are useful for developing high-frequency electron devices.

  17. Planar intrinsic Josephson junctions with in-plane aligned YBCO films

    International Nuclear Information System (INIS)

    Zhang, L; Moriya, M; Kobayashi, T; Goto, T; Mukaida, M

    2002-01-01

    Planar type devices were fabricated by patterning in-plane aligned YBa 2 Cu 3 O 7-δ (YBCO) films. The current-voltage characteristics along the c-axis at various temperatures and oxygen contents were measured. The current voltage curves showing supercurrent and hysteresis were obtained for the samples annealed at an oxygen pressure of 1.3 x 10 4 Pa, while the supercurrent and hysteresis became smaller and even disappeared as the oxygen pressure decreased. The relationships between the critical currents and temperatures are similar to those of d-wave superconducting tunnel junctions. These results indicate the formation of stacks of intrinsic Josephson junctions, which are useful for developing high-frequency electron devices

  18. Enhanced flux-pinning in fluorine-free MOD YBCO films by chemical doping

    Energy Technology Data Exchange (ETDEWEB)

    Wang, W.T.; Pu, M.H.; Yang, Y. [Key Laboratory of Magnetic Levitation and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Zhang, H. [Department of Physics, Peking University, Beijing 100871 (China); Cheng, C.H. [Superconductivity Research Group, School of Materials Science and Engineering, University of New South Wale, Sydney, 2052 NSW (Australia); Zhao, Y., E-mail: yzhao@swjtu.edu.c [Key Laboratory of Magnetic Levitation and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Superconductivity Research Group, School of Materials Science and Engineering, University of New South Wale, Sydney, 2052 NSW (Australia)

    2010-11-01

    YBCO films without and with dilute cobalt and zinc doping were prepared on (0 0 l) LaAlO{sub 3} substrate by non-fluorine metal organic deposition method. Effects of dilute cobalt and zinc doping on biaxial texture, microstructure and flux-pinning properties of YBCO films were investigated. The surface density and smoothness of the doped YBCO films have been distinctly improved compared with that of the pure film. Dilute cobalt- and zinc-doped YBCO films exhibit significantly enhanced J{sub c} values in the magnetic field. The best result is achieved in the cobalt-doped YBCO film. At 77 K, J{sub c} values of cobalt-doped film are 1.7 and 5.4 times higher than that of pure film in 0.5 T and 1.5 T, respectively. These results strongly suggest that dilute cobalt and zinc doping is a promising way to increase the current carrying capability of YBCO films.

  19. Iron-YBCO heterostructures and their application for trapped field superconducting motor

    Energy Technology Data Exchange (ETDEWEB)

    Granados, X [Institut de Ciencia de Materials de Barcelona, ICMAB-CSIC, Campus U.A. Barcelona, 08193 Bellaterra (Spain); Bartolome, E [Institut de Ciencia de Materials de Barcelona, ICMAB-CSIC, Campus U.A. Barcelona, 08193 Bellaterra (Spain); Obradors, X [Institut de Ciencia de Materials de Barcelona, ICMAB-CSIC, Campus U.A. Barcelona, 08193 Bellaterra (Spain); Tornes, M [ETSE-UAB, Barcelona (Spain); Rodrigues, L [UNL, Lisbon (Portugal); Gawalek, W [IPHT, Jena (Germany); McCulloch, M [Department Engineering Science, University of Oxford, Oxford (United Kingdom); Hughes, D Dew [Department Engineering Science, University of Oxford, Oxford (United Kingdom); Campbell, A [IRC-UCAM, Cambridge (United Kingdom); Coombs, T [IRC-UCAM, Cambridge (United Kingdom); Ausloos, M [SUPRATEC, Liege (Belgium); Cloots, R [SUPRATEC, Liege (Belgium)

    2006-06-01

    In this work we report on the magnetic behavior of the heterostructures formed by bulk based YBCO rings and ferromagnetic yoke. The magnetization cycle has been performed by an In-Field Hall Mapping technique. A video-like recording of the magnetization process makes it possible to obtain the magnetization of selected areas. The current flowing through the superconducting rings can be deduced from the magnetic field maps. The displacement of the peak of magnetization due to the flux reversal produced by the magnetization of the yoke is also considered. These hybrid heterostructures formed by ferromagnetic and superconducting material have been applied in the construction of the rotor for a brushless AC motor. The design and construction of this machine was carried out within the framework of the TMR Network SUPERMACHINES. The rotor has been designed in a quadrupolar configuration by cutting large YBCO 'window frames' from seeded melt-textured single domain YBCO pellets. This rotor has been coupled to a conventional stator of copper coils wound on an iron armature. The stator can be excited both in bipolar or quadrupolar mode. We report on the behaviour of the motor after a field cooling process when excited in quadrupolar mode.

  20. Iron-YBCO heterostructures and their application for trapped field superconducting motor

    International Nuclear Information System (INIS)

    Granados, X; Bartolome, E; Obradors, X; Tornes, M; Rodrigues, L; Gawalek, W; McCulloch, M; Hughes, D Dew; Campbell, A; Coombs, T; Ausloos, M; Cloots, R

    2006-01-01

    In this work we report on the magnetic behavior of the heterostructures formed by bulk based YBCO rings and ferromagnetic yoke. The magnetization cycle has been performed by an In-Field Hall Mapping technique. A video-like recording of the magnetization process makes it possible to obtain the magnetization of selected areas. The current flowing through the superconducting rings can be deduced from the magnetic field maps. The displacement of the peak of magnetization due to the flux reversal produced by the magnetization of the yoke is also considered. These hybrid heterostructures formed by ferromagnetic and superconducting material have been applied in the construction of the rotor for a brushless AC motor. The design and construction of this machine was carried out within the framework of the TMR Network SUPERMACHINES. The rotor has been designed in a quadrupolar configuration by cutting large YBCO 'window frames' from seeded melt-textured single domain YBCO pellets. This rotor has been coupled to a conventional stator of copper coils wound on an iron armature. The stator can be excited both in bipolar or quadrupolar mode. We report on the behaviour of the motor after a field cooling process when excited in quadrupolar mode

  1. Quick screening for new flux pinning materials in YBCO films with the combinatorial-PLD method

    International Nuclear Information System (INIS)

    Yoshimura, T.; Ichino, Y.; Yoshida, Y.; Takai, Y.; Kita, R.; Suzuki, K.; Takeuchi, T.

    2011-01-01

    An effective way to improve the superconducting properties in REBa 2 Cu 3 O y (REBCO) films under a magnetic field is to dope artificial pinning centers (APC). The pinning performance depends on the content of the APC materials. Usually, the optimal APC content is explored by preparing films one at a time from the REBCO target using different APC material content, which is an extremely time-consuming process. The combinatorial-PLD (C-PLD) method allowed us to prepare films that continuously changed in composition across a single substrate. In this study, we used the C-PLD method to prepare BaSnO 3 (BSO)-doped YBCO films. The films were deposited on SrTiO 3 substrate using a fourth-harmonic Nd:YAG laser. From the results of the J c -B curves at 77 K and B//c, the film that contained 3.2 vol.% of BSO exhibited the best pinning performance in this study. We showed that the C-PLD method was efficient for quick screening of the optimal APC content with only one deposition. We also used the C-PLD method to explore new APC materials, and proved that it can quickly evaluate the new APC materials Ba 3 Cu 3 In 4 O 12 and BaTbO 3 .

  2. Preparation of PZT/YBCO/YAlO heterostructure thin films by KrF excimer laser ablation

    International Nuclear Information System (INIS)

    Ebihara, Kenji; Kurogi, Hiromitsu; Yamagata, Yukihiko; Ikegami, Tomoaki; Grishin, A.M.

    1998-01-01

    The perovskite oxide YBa 2 Cu 3 O 7-x (YBCO) and Pb(Zr x Ti 1-x )O 3 (PZT) thin films have been deposited for superconducting-ferroelectric devices. KrF excimer laser ablation technique was used at the deposition conditions of 200--600 mTorr O 2 , 2-3J/cm 2 and 5--10 Hz operation frequency. Heterostructures of PZT-YBCO-YAlO 3 :Nd show the zero resistivity critical temperature of 82 K and excellent ferroelectric properties of remnant polarization 32 microC/cm 2 , coercive force of 80 kV/cm and dielectric constant 800. Cycling fatigue characteristics and leakage current are also discussed

  3. Incorporation of self-organised gold nano crystals in YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} thin films: Modification of superconducting properties

    Energy Technology Data Exchange (ETDEWEB)

    Katzer, Christian; Michalowski, Peter; Westerhausen, Markus; Koch, Stefanie; Schmidl, Frank; Seidel, Paul [Institut fuer Festkoerperphysik, Friedrich-Schiller-Universitaet Jena, Helmholtzweg 5, 07743 Jena (Germany); Treiber, Sebastian [Max-Planck-Institut fuer Intelligente Systeme, Heisenbergstrasse 3, 70569 Stuttgart (Germany); Albrecht, Joachim [Hochschule Aalen, Beethovenstrasse 1, 73430 Aalen (Germany)

    2012-07-01

    Using pulsed laser deposition we are able to fabricate and examine Yttrium-Barium-Copper-Oxide (YBCO) thin films of high quality. A particular point of interest thereby is the influence of a pre-deposited gold layer with a well-defined film thickness. During the growth of the YBCO thin film the intermediate gold layer self assembles into crystalline nano particles, which modify the growth conditions and hence the physical properties of the growing YBCO. We report on the modification of structural and superconducting properties of our YBCO thin films (such as rocking curve widths, critical temperature T{sub c} and critical current density j{sub c}) comparing conventional to Au added YBCO. The temperature dependence of the critical current density thereby was determined using transport measurements as well as magneto-optical measurements. Furthermore investigations of the flux noise of our gold modified YBCO films are presented.

  4. The growth of large-area superconducting YBa2Cu3O7-x thin films by pulsed laser ablation

    International Nuclear Information System (INIS)

    Lai, H.C.; Chang, C.M.; Lin, R.J.; Liu, R.S.

    1996-01-01

    In-situ growth of 2-in. diameter superconducting YBa 2 Cu 3 O 7-x (YBCO) thin films using an excimer KrF pulsed laser has been studied. Films with critical transition temperature (T c,0 ) of 89±1 K and critical current density (J c,77K ) in excess of 1 x 10 6 A cm -2 have been prepared routinely. Uniformity in film thickness of below ±15% and film composition of ±5% have been measured. The effects of gas nozzle geometry and target evolution during ablation on the superconducting properties and surface morphology of YBCO thin films have also been investigated. (orig.)

  5. Superconducting thin films

    International Nuclear Information System (INIS)

    Hebard, A.F.; Vandenberg, J.M.

    1982-01-01

    This invention relates to granular metal and metal oxide superconducting films formed by ion beam sputter deposition. Illustratively, the films comprise irregularly shaped, randomly oriented, small lead grains interspersed in an insulating lead oxide matrix. The films are hillock-resistant when subjected to thermal cycling and exhibit unusual josephson-type switching characteristics. Depending on the oxygen content, a film may behave in a manner similar to that of a plurality of series connected josephson junctions, or the film may have a voltage difference in a direction parallel to a major surface of the film that is capable of being switched from zero voltage difference to a finite voltage difference in response to a current larger than the critical current

  6. BaF2 POST-DEPOSITION REACTION PROCESS FOR THICK YBCO FILMS

    International Nuclear Information System (INIS)

    SUENAGA, M.; SOLOVYOV, V.F.; WU, L.; WIESMANN, H.J.; ZHU, Y.

    2001-01-01

    The basic processes of the so-called BaF 2 process for the formation of YBa 2 Cu 3 O 7 , YBCO, films as well as its advantages over the in situ formation processes are discussed in the previous chapter. The process and the properties of YBCO films by this process were also nicely described in earlier articles by R. Feenstra, (et al.) Here, we will discuss two pertinent subjects related to fabrication of technologically viable YBCO conductors using this process. These are (1) the growth of thick (>> 1 microm) c-axis-oriented YBCO films and (2) their growth rates. Before the detail discussions of these subjects are given, we first briefly discuss what geometrical structure a YBCO-coated conductor should be. Then, we will provide examples of simple arguments for how thick the YBCO films and how fast their growth rates need to be. Then, the discussions in the following two sections are devoted to: (1) the present understanding of the nucleation and the growth process for YBCO, and why it is so difficult to grow thick c-axis-oriented films (> 3 microm), and (2) our present understanding of the YBCO growth-limiting mechanism and methods to increase the growth rates. The values of critical-current densities J c in these films are of primary importance for the applications,. and the above two subjects are intimately related to the control of J c of the films. In general, the lower the temperatures of the YBCO formation are the higher the values of J c of the films. Thus, the present discussion is limited to those films which are reacted at ∼735 C. This is the lowest temperature at which c-axis-oriented YBCO films (1-3 microm thick) are comfortably grown. It is also well known that the non-c-axis oriented YBCO platelets are extremely detrimental to the values of J c such that their effects on J c dwarf essentially all of other microstructural effects which control J c . Hence, the discussion given below is mainly focused on how to avoid the growth of these crystallites

  7. Superconducting thin films of YBa2Cu3O7-x

    International Nuclear Information System (INIS)

    Hudner, J.

    1993-01-01

    Thin films of the high temperature superconductor YBa 2 Cu 3 O 7-x (YBCO) are of significance in fundamental studies of oxide superconductors and for prospected electronic applications based on superconductors operating at liquid nitrogen temperatures (T= 77 K). Synthesis of YBCO thin films is complex and a large part of this thesis has been devoted to the elaboration of various techniques in forming YBCO thin films. A general observation was that synthesis of YBCO films exhibiting high zero-resistivity temperatures temperatures (T c ) ≥ 88 K and elevated critical current densities (J c ) ≥ 10 6 A/cm 2 at 77 K was possible under widely different conditions of film growth. For the BaF 2 -based method, various substrate materials were investigated. Among perovskite related substrates with low losses in the high frequency regime, LaA10 3 was found to yield YBCO films exhibiting the highest quality electrical properties. A study of YBCO film interaction with sapphire substrates was performed. It was suggested that the YBCO film on sapphire consists of weakly coupled superconducting grains. Compositional effects of Y, BA and Cu for MOCVD-YBCO films were examined with respect to morphology, structure, resistivity, as susceptibility and J c (T). High T c :s and J c :s were observed for an anomalous large compositional range of Cu in off-compositional YBCO films. This was shown to be related to the formation of Cu-rich precipitates embedded within a c-Axis oriented stoichiometric YBCO film matrix. Thermal critical current behavior at zero field in thin films of YBCO fabricated by various methods has been studied by three techniques: transport measurements on patterned microbridges, dc magnetization hysteresis loops using the Bean model and non-linear ac susceptibility analysis. Absolute critical current values obtained form the two former techniques when measured on the same YBCO film were observed to differ about a factor of two. The feasibility of non-linear ac

  8. Effect of plasma on the superconductive property of YBCO system

    International Nuclear Information System (INIS)

    Chaudhary, K.A.; Anwar, M.I.; Zakaullah, M.; Alamgir, K.; Murtaza, G.; Haq, A.U.

    1999-01-01

    Oxygen deficient Y/sub 1/Ba/sub 2/Cu 3/O/sub 7-x/ samples are exposed to the rarefied are discharge. The air plasma has gas and electron temperatures as 170 deg. C and 2.1 eV, respectively. As a result of plasma treatment the semiconducting tetragonal phase transformed into superconducting orthorhombic phase with Tc= 84K the phase relating properties have been investigated by monochromated X-ray diffraction and low temperature resistivity measurements. (author)

  9. Enhancement of flux pinning of TFA-MOD YBCO thin films by embedded nanoscale Y2O3

    International Nuclear Information System (INIS)

    Cui, X M; Tao, B W; Tian, Z; Xiong, J; Zhang, X F; Li, Y R

    2006-01-01

    YBCO films with different levels of excess yttrium were prepared on single-crystal LaAlO 3 with metal-organic deposition using trifluoroacetates (TFA-MOD). X-ray diffraction and transmission electron microscope measurements revealed excess yttrium in YBCO in the form of nanoscale Y 2 O 3 with (400) preferred orientation. The field dependence of J c demonstrated that YBCO films with Y 2 O 3 doping had enhanced J c in comparison with stoichiometric YBCO films in the magnetic fields. We think the reason for this is that the Y 2 O 3 nanoparticles act as pinning centres. YBCO films with 60% yttrium excess display 43% increased J c compared to stoichiometric YBCO films at a magnetic field of 1 T

  10. The effect of a thin silver layer on the critical current of epitaxial YBCO films

    International Nuclear Information System (INIS)

    Polturak, E.; Koren, G.; Cohen, D.; Cohen, D.; Snapiro, I.

    1992-01-01

    We compare measurements of the critical current density of an epitaxial YBCO film with that of an identical film overlaid by a thin silver layer. We find that the presence of the silver lowers Tc of the film by about 1.5 K, which is two orders of magnitude larger than predicted by the theory of the proximity effect for our experimental conditions. In addition, J c of the Ag/YBCO film near Tc is also significantly lower than that of the bare YBCO film. We propose two alternate interpretations of this effect, one in terms of destabilization of the flux distribution in the film and the other making use of the effect of the silver on the Bean-Livingston surface barrier for the initial penetration of flux. The latter seems the more plausible explanation of our results. (orig.)

  11. Superconductivity

    International Nuclear Information System (INIS)

    2007-01-01

    During 2007, a large amount of the work was centred on the ITER project and related tasks. The activities based on low-temperature superconducting (LTS) materials included the manufacture and qualification of ITER full-size conductors under relevant operating conditions, the design of conductors and magnets for the JT-60SA tokamak and the manufacture of the conductors for the European dipole facility. A preliminary study was also performed to develop a new test facility at ENEA in order to test long-length ITER or DEMO full-size conductors. Several studies on different superconducting materials were also started to create a more complete database of superconductor properties, and also for use in magnet design. In this context, an extensive measurement campaign on transport and magnetic properties was carried out on commercially available NbTi strands. Work was started on characterising MgB 2 wire and bulk samples to optimise their performance. In addition, an intense experimental study was started to clarify the effect of mechanical loads on the transport properties of multi-filamentary Nb 3 Sn strands with twisted or untwisted superconducting filaments. The experimental activity on high-temperature superconducting (HTS) materials was mainly focussed on the development and characterisation of YBa 2 Cu 3 O 7-X (YBCO) based coated conductors. Several characteristics regarding YBCO deposition, current transport performance and tape manufacture were investigated. In the framework of chemical approaches for YBCO film growth, a new method, developed in collaboration with the Technical University of Cluj-Napoca (TUCN), Romania, was studied to obtain YBCO film via chemical solution deposition, which modifies the well-assessed metallic organic deposition trifluoroacetate (MOD-TFA) approach. The results are promising in terms of critical current and film thickness values. YBCO properties in films with artificially added pinning sites were characterised in collaboration with

  12. Superconducting-electromagnetic hybrid bearing using YBCO bulk blocks for passive axial levitation

    Science.gov (United States)

    Nicolsky, R.; de Andrade, R., Jr.; Ripper, A.; David, D. F. B.; Santisteban, J. A.; Stephan, R. M.; Gawalek, W.; Habisreuther, T.; Strasser, T.

    2000-06-01

    A superconducting/electromagnetic hybrid bearing has been designed using active radial electromagnetic positioning and a superconducting passive axial levitator. This bearing has been tested for an induction machine with a vertical shaft. The prototype was conceived as a four-pole, two-phase induction machine using specially designed stator windings for delivering torque and radial positioning simultaneously. The radial bearing uses four eddy-current sensors, displaced 90° from each other, for measuring the shaft position and a PID control system for feeding back the currents. The stator windings have been adapted from the ones of a standard induction motor. The superconducting axial bearing has been assembled with commercial NdFeB permanent magnets and a set of seven top-seeded-melt-textured YBCO large-grain cylindrical blocks. The bearing set-up was previously simulated by a finite element method for different permanent magnet-superconductor block configurations. The stiffness of the superconducting axial bearing has been investigated by measuring by a dynamic method the vertical and transversal elastic constants for different field cooling processes. The resulting elastic constants show a linear dependence on the air gap, i.e. the clearance between the permanent magnet assembly and the set of superconducting large-grain blocks, which is dependent on cooling distance.

  13. Quantification of oxygen and carbon in high Tc superconducting films by (α,α) elastic resonance technique

    International Nuclear Information System (INIS)

    Vizkelethy, G.; Revesz, P.

    1993-01-01

    The quantification of oxygen and carbon in high-temperature (T c ) superconducting oxide thin films was made by employing elastic resonance in He backscattering analysis. A method combining the oxygen resonance technique and channeling was presented for measuring the nature of the oxygen disorder near the surface and the interface in a YBCO superconducting film grown on an MgO substrate. The oxygen resonance technique was used to quantify the oxygen profiling in the metal/YBCO contacts, showing that Zr and Nb act as sinks to oxygen from YBCO films and are oxidized in the forms Zr/ZrO 2 /YBCO/MgO and Nb 0.2 O/YBCO/MgO after annealing in a vacuum at 350 o C. We combined the carbon and oxygen resonances to determine the carbon contamination and oxygen concentration changes on the YBCO surface after coating and baking the photoresist. Residual carbon on the surface and a thin layer of oxygen depletion near the YBCO surface have been observed. The residual carbon in Bi 2 Sr 2 CaCu 2 O 8 films made by the decomposition of metallo-organic precursors was quantified using carbon resonance. (author)

  14. Final report: High current capacity high temperature superconducting film based tape for high field magnets

    International Nuclear Information System (INIS)

    Ying Xin

    2000-01-01

    The primary goal of the program was to establish the process parameters for the continuous deposition of high quality, superconducting YBCO films on one meter lengths of buffered RABiTS tape using MOCVD and to characterize the potential utility of the resulting tapes in high field magnet applications

  15. Pulsed laser deposition of YBCO films on ISD MgO buffered metal tapes

    CERN Document Server

    Ma, B; Koritala, R E; Fisher, B L; Markowitz, A R; Erck, R A; Baurceanu, R; Dorris, S E; Miller, D J; Balachandran, U

    2003-01-01

    Biaxially textured magnesium oxide (MgO) films deposited by inclined-substrate deposition (ISD) are desirable for rapid production of high-quality template layers for YBCO-coated conductors. High-quality YBCO films were grown on ISD MgO buffered metallic substrates by pulsed laser deposition (PLD). Columnar grains with a roof-tile surface structure were observed in the ISD MgO films. X-ray pole figure analysis revealed that the (002) planes of the ISD MgO films are tilted at an angle from the substrate normal. A small full-width at half maximum (FWHM) of approx 9deg was observed in the phi-scan for ISD MgO films deposited at an inclination angle of 55deg . In-plane texture in the ISD MgO films developed in the first approx 0.5 mu m from the substrate surface, and then stabilized with further increases in film thickness. Yttria-stabilized zirconia and ceria buffer layers were deposited on the ISD MgO grown on metallic substrates prior to the deposition of YBCO by PLD. YBCO films with the c-axis parallel to the...

  16. Fabrication and characterization of hybrid Nb-YBCO dc SQUIDs

    International Nuclear Information System (INIS)

    Frack, E.K.; Drake, R.E.; Patt, R.; Radparvar, M.

    1991-01-01

    This paper reports on the fabrication of hybrid low T c /high T c dc SQUIDs of two flavors. The first kind utilizes niobium tunnel junctions and a YBCO film strip as the most inductive portion of the SQUID loop. This configuration allows a direct measurement of the inductance of the YBCO microstrip from which the effective penetration depth can be calculated. The successful fabrication of these SQUIDs has required 1. superconducting Nb-to-YBCO contacts, 2. deposition and patterning of an SiO 2 insulation layer over YBCO, and 3. selective patterning of niobium and SiO 2 relative to YBCO. All these process steps are pertinent to the eventual use of YBCO thin films in electronic devices

  17. Growth and characterization of high-Tc Y1Ba2Cu3O7-x superconducting thin films by chemical vapor deposition

    International Nuclear Information System (INIS)

    Feng, A.

    1992-01-01

    In chapter I, the current status of high-Tc superconductors (especially Y 1 Ba 2 Cu 3 O 7-x ), their microstructures and their unique physical properties are reviewed. An introduction to the potential and importance of those high-Tc superconductors in practical applications, especially for the application of YBCO thin films in microelectronics, is given. A general description of the common YBCO thin film fabrication and characterization techniques is also presented in this first chapter. Chapter II describes a new CVD process, temperature-controlled chemical vapor deposition (TC-CVD) for the growth of YBCO superconducting thin films on substrates of practical importance, such as sapphire (Al 2 O 3 ) and on substrates of lattice matched perovskite-type single crystals, such as LaAlO 3 . In order to verify the viability of this new CVD process the qualities of YBCO superconducting thin films were examined by various characterization methods, such as resistivity vs. temperature (R vs. T), scanning electron microscopy (SEM), X-ray diffraction (XRD), and magnetic susceptibility (x) measurements. Chapter III deals with the effect of substrate temperature on the properties of YBCO thin films made by TC-CVD. The principle objective of this study is to raise the transition temperature and critical current densities of CVD YBCO superconducting thin films. Understanding the relations between YBCO film growth process and varying substrate temperatures proved to be crucial in reaching this goal. The authors present the characterization results of YBCO thin films produced by different temperature schemes, to illustrate the importance of varying substrate temperature during the film growth. In chapter IV, the Rutherford backscattering (RBS) channeling technique is described. They have used RBS channeling to characterize the epitaxial YBCO thin film's crystallinity and lattice alignment. Transmission electron microscopy studies are also included

  18. Mechanical characterization of YBCO thin films using nanoindentation and finite element method

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Weixing [The Ministry of Education of China (China). Key Lab. of Mechanics on Environment and Disaster in Western China; Lanzhou Univ. (China). College of Civil Engineering and Mechanics

    2017-09-15

    The mechanical properties of YBCO thin film deposited on SrTiO{sub 3} (100) substrates by magnetron sputtering were determined using Berkovich nanoindentation and scanning electron microscopy. Hardness and elastic modulus were determined via the Oliver-Pharr method from indentation load-depth curves. The hardness values of the YBCO thin film show depth dependence, i. e., indentation size effect, which arose from the surface roughness as detected by scanning electron microscopy. Multiple pop-in events were observed on the loading curves, however, no obvious pop-out takes place during the elastic recovery. In addition, an effective analytical method accommodating the indenter imperfection was proposed and validated against experimental data in terms of elastic modulus, yield stress and friction angle using the Drucker-Prager yield criterion for the YBCO thin film.

  19. Studies of proximity-effect and tunneling in YBCO/metal layered films

    Energy Technology Data Exchange (ETDEWEB)

    Greene, L.H.; Barner, J.B.; Feldmann, W.L.; Farrow, L.A.; Miceli, P.F.; Ramesh, R.; Wilkens, B.J.; Bagley, B.G.; Tarascon, J.M.; Wernick, J.H. (Bellcore, Red Bank, NJ (USA)); Giroud, M. (CRTBT-CNRS, Grenoble (France)); Rowell, J.M. (Conductus, Sunnyvale, CA (USA))

    1989-12-01

    The short coherence length of the high-Tc superconductors, coupled with their tendency to form non-superconducting surface layers, accounts for the difficulty in achieving good tunnel junctions. A proximity layer of a longer coherence length normal metal (N) is expected to ''draw out'' Cooper pairs. Our goal is to fabricate reproducible, planar tunnel junctions of SNIS layered structures for proximity tunneling spectroscopy. Such structures of YBCO/N/I/Pb and SNS structures of YBCO/N/Pb indicate that the normal metal produces a low resistance contact to the YBCO surface with a supercurrent observed in the SNS. The insulating barrier in the SNIS is reproducible, insulating and continuous: A sharp Pb gap and phonons from the counter-electrode are routinely observed. (orig.).

  20. Studies of proximity-effect and tunneling in YBCO/metal layered films

    International Nuclear Information System (INIS)

    Greene, L.H.; Barner, J.B.; Feldmann, W.L.; Farrow, L.A.; Miceli, P.F.; Ramesh, R.; Wilkens, B.J.; Bagley, B.G.; Tarascon, J.M.; Wernick, J.H.; Giroud, M.; Rowell, J.M.

    1989-01-01

    The short coherence length of the high-T c superconductors, coupled with their tendency to form non-superconducting surface layers, accounts for the difficulty in achieving good tunnel junctions. A proximity layer of a longer coherence length normal metal (N) is expected to draw out Cooper pairs. The authors' goal is to fabricate reproducible, planar tunnel junctions of SNIS layered structures for proximity tunneling spectroscopy. They discuss how such structures of YBCO/N/I/Pb and SNS structures of YBCO/N/Pb indicate that the normal metal produces a low resistance contact to the YBCO surface with a supercurrent observed in the SNS. The insulating barrier in the SNIS is reproducible, insulating and continuous: A sharp Pb gap and phonons from the counter-electrode are routinely observed

  1. Anisotrophic currents and flux jumps in high-T-c superconducting films with self-organized arrays of planar defects

    DEFF Research Database (Denmark)

    Yurchenko, V.V.; Qviller, A.J.; Mozhaev, P.B.

    2010-01-01

    Regular arrays of planar defects with a period of a few nanometers can be introduced in superconducting YBa2Cu3O7-delta (YBCO) thin films by depositing them on vicinal (also called miscut or tilted) substrates. This results in the anisotropy of critical currents flowing in the plane of the film. ...

  2. Resistive switching phenomenon and hole wind effect in YBCO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Truchly, Martin; Plecenik, Tomas [Department of Experimental Physics, Comenius University, Bratislava (Slovakia); Zhitlukhina, Elena [Donetsk Institute for Physics and Engineering, Kyiv (Ukraine)

    2016-07-01

    We present an overview of our experimental and theoretical activities aimed to clarify the mechanism of resistive memory effects in YBCO thin layers. The phenomenon was studied by scanning spreading resistance microscopy (SSRM) and scanning tunneling microscopy (STM) techniques. The most striking feature uncovered (in contrast to previous experiments on planar bilayers with YBCO films) was the opposite voltage-bias polarity of the switching effect in all SSRM and a number of STM measurements. Observed hysteresis in current-voltage characteristics is interpreted as a movement of oxygen vacancies in the vicinity of the tip-YBCO contact. Since the charge distribution in YBCO samples is expected to be strongly inhomogeneous, the balance between the direct electrostatic force on activated oxygen ions and that caused by momentum exchange with the current carriers (holes) hitting them determines direction in which the oxygen vacancies are moving. We propose a minimalist model with the only fitting parameter that accounts for the resistance hysteresis phenomenon in the YBCO films studied.

  3. Study on optimization of YBCO thin film stack for compact NMR magnets

    International Nuclear Information System (INIS)

    Kim, S.B.; Kimoto, T.; Hahn, S.; Iwasa, Y.; Voccio, J.; Tomita, M.

    2013-01-01

    Highlights: ► Stacking methods for compact NMR magnet using YBCO thin films were tested. ► The stacking angles are 0°, 22.5° and 90° against the rolling direction. ► The best spatial field homogeneity was obtained in rotation angle of 22.5°. ► The maximum trapped magnetic fields of 0.4 T was obtained at 77.4 K. ► The maximum trapped magnetic fields of 0.95 T was obtained at 21 K. -- Abstract: A compact high temperature superconducting (HTS) magnet, which consists of a stack of 500 HTS thin film annuli, was constructed and tested. Each thin film annulus, manufactured by the AMSC using the Rolling Assisted Bi-axially Textured Substrate (RABiTS) method, has a square cross-section of 40 mm × 40 mm with a thickness of 80 m. It has a 25-mm center hole created by machining. This paper reports a study on the anisotropic J c issue due to the rolling procedure of the Ni substrate direction and its impact on field homogeneity. Also, three different stacking methods with rotation angles of 22.5°, 90°, and 0° against the rolling direction have been tested to study their impacts on strength, spatial homogeneity, and temporal stability of trapped fields. Finally, the 500-annulus magnet was tested at 21 K under a cryogen-free environment using a GM cryocooler. The spatial field homogeneity and temporal stability were measured at 21 K and compared with those obtained in a bath of liquid nitrogen at 77 K

  4. Critical current density and microwave surface resistance of 5-cm-diameter YBCO films on LaAlO3 substrates prepared by MOD using an infrared image furnace

    International Nuclear Information System (INIS)

    Manabe, T.; Kondo, W.; Yamaguchi, I.; Sohma, M.; Tsuchiya, T.; Tsukada, K.; Mizuta, S.; Kumagai, T.

    2005-01-01

    Inductive critical current density (J c ) and microwave surface resistance (R s ) were investigated for 0.7-μm-thick epitaxial YBa 2 Cu 3 O 7-y (YBCO) films on 5-cm-diameter LaAlO 3 substrates prepared by a chemical solution-based metal organic deposition (MOD) process using an infrared image furnace. By varying the heating rate at ramp during the final heat treatment, we obtained various orientations of YBCO; the c- and a-axis orientation at a slower rate, i.e., 20-100 deg C/min while the pure c-axis orientation at a faster rate, 200 deg C/min. The c-axis-oriented YBCO films showed excellent superconducting properties; for example, a high inductive-J c (77 K) of 2.6 MA/cm 2 and low R s (12 GHz)'s of 0.24 and 0.52 mΩ at 50 and 77 K, respectively, by a sapphire rod resonator method. The c- and a-axis-oriented films exhibited a lower J c and a higher R s . It was found that the J c and R s values of MOD-derived YBCO films showed a strong correlation; approximately, R s is inversely proportional to J c . This correlation is in good agreement with a previous report by Ohshima et al. for sputtered-YBCO films on BaSnO 3 -buffered MgO substrates

  5. High-Jc YBa2Cu3O7-x-Ag superconducting thin films synthesized through a fluorine-free MOD method

    DEFF Research Database (Denmark)

    Tang, Xiao; Yue, Zhao; Wu, W.

    2015-01-01

    Obtaining a high critical current density (Jc) remains the main challenge in developing fluorine-free metal organic deposition (MOD) methods to fabricate YBCO superconducting thin films. Silver addition was used to raise the Jc values in this research work. By reacting with propionic acid...... and ammonia, AgNO3 was initially mixed with YBCO carboxylate precursors dissolved in methanol. High-temperature in situ XRD measurements on the YBCO-Ag powders revealed that silver addition lowers the incongruent melting temperature of YBCO to 760°C and resulted in a smooth surface morphology of the YBCO...... films at a temperature as low as 760°C. Grain growth and intergranular conductivity were also found to be improved by silver doping. After annealing under optimized conditions, a high Jc of 4.6MA/cm2 was obtained in a YBCO-Ag thin film with 10 wt% Ag....

  6. Growth orientation and superconducting properties of YBa2Cu3O7-δ films prepared by the low-fluorine sol-gel process

    International Nuclear Information System (INIS)

    Lei Li; Zhao Gaoyang; Xu Hui; Zhao Juanjuan

    2010-01-01

    YBa 2 Cu 3 O 7-δ (YBCO) films were deposited on (100)-oriented LaAlO 3 (LAO) single crystal substrates by the dip-coating process using low-fluorine solution. Their microstructures were characterized with the aid of X-ray diffractometry, scanning electron microscopy and high-resolution transmission electron microscopy. Their superconducting properties were measured by the standard four-probe method. The experiment results show that the film obtained under high enough humidity conditions exhibits better c-axis texture and superconducting properties than the film under a relatively low humidity conditions. Based on the classical nucleation and chemical reaction thermodynamics theory, the underlying crystalline and growth mechanisms of YBCO films under certain humidity conditions are explained in combination with our experimental results. It is suggested that the unreacted intermediate phases such as BaF 2 and CuO aggregated in the YBCO grain boundary will cause lattice distortion in the YBCO matrix and further induce the formation of a-axis oriented YBCO grains as crystallization proceeds. Therefore, it is believed that the relative content of water vapor within the heat-treatment atmosphere plays quite an important role in the preparation of c-axis oriented YBCO film with good superconducting properties. (semiconductor materials)

  7. Preparation of PZT thin films on YBCO electrodes by KrF excimer laser ablation technique

    International Nuclear Information System (INIS)

    Kurogi, H.; Yamagata, Y.; Ebihara, K.

    1998-01-01

    Pb(Zr X Ti 1-X )O 3 (PZT) films have excellent ferroelectric, optical, piezoelectric, and pyroelectric properties. We prepared PZT thin films by the excimer laser ablation technique. A pulsed KrF excimer laser (Lambda Physik LPX305icc, pulse duration of 25 ns, λ=248 nm, 850 mJ Max.) was used to ablate the bulk targets. We investigated the influence of bottom electrode materials on the characteristics of the PZT thin films prepared on Pt and YBCO underlayers. The X-ray diffraction (XRD) patterns showed that the PZT films prepared with a laser fluence of 2 Jcm -2 on YBCO/MgO(100) substrate at a wide temperature range of 550-680 C have a perovskite (001) structure. At the same laser fluence, the PZT films prepared on Pt/MgO(100) substrate have a perovskite (001) structure only at 650 C. The polarization-electric field (P-E) characteristics and fatigue properties of PZT thin films were measured by the Sawyer-Tower circuit. The remnant polarization and coercive field have been found to be P r =15 μC cm -2 , 30 μC cm -2 and E c =200 kV cm -1 , 100 kV cm -1 for Au/PZT/Pt/MgO and Au/PZT/YBCO/MgO correspondingly. The remnant polarization of Au/PZT/YBCO/MgO thin film was reduced to one-half after about 10 8 cycles of switching. (orig.)

  8. Preparation of PZT thin films on YBCO electrodes by KrF excimer laser ablation technique

    Energy Technology Data Exchange (ETDEWEB)

    Kurogi, H; Yamagata, Y; Ebihara, K [Kumamoto Univ. (Japan). Dept. of Electr. Eng. and Comput. Sci.; Inoue, N [Kyushu Electric Power Co., Inc., Suizenji, 1-6-36, Kumamoto 862 (Japan)

    1998-03-01

    Pb(Zr{sub X}Ti{sub 1-X})O{sub 3} (PZT) films have excellent ferroelectric, optical, piezoelectric, and pyroelectric properties. We prepared PZT thin films by the excimer laser ablation technique. A pulsed KrF excimer laser (Lambda Physik LPX305icc, pulse duration of 25 ns, {lambda}=248 nm, 850 mJ Max.) was used to ablate the bulk targets. We investigated the influence of bottom electrode materials on the characteristics of the PZT thin films prepared on Pt and YBCO underlayers. The X-ray diffraction (XRD) patterns showed that the PZT films prepared with a laser fluence of 2 Jcm{sup -2} on YBCO/MgO(100) substrate at a wide temperature range of 550-680 C have a perovskite (001) structure. At the same laser fluence, the PZT films prepared on Pt/MgO(100) substrate have a perovskite (001) structure only at 650 C. The polarization-electric field (P-E) characteristics and fatigue properties of PZT thin films were measured by the Sawyer-Tower circuit. The remnant polarization and coercive field have been found to be P{sub r}=15 {mu}C cm{sup -2}, 30 {mu}C cm{sup -2} and E{sub c}=200 kV cm{sup -1}, 100 kV cm{sup -1} for Au/PZT/Pt/MgO and Au/PZT/YBCO/MgO correspondingly. The remnant polarization of Au/PZT/YBCO/MgO thin film was reduced to one-half after about 10{sup 8} cycles of switching. (orig.) 7 refs.

  9. Enhanced flux pinning in MOCVD-YBCO films through Zr additions : systematic feasibility studies.

    Energy Technology Data Exchange (ETDEWEB)

    Aytug, T.; Paranthaman, M.; Specht, E. D.; Zhang, Y.; Kim, K.; Zuev, Y. L.; Cantoni, C.; Goyal, A.; Christen, D. K.; Maroni, V. A.; Chen, Y.; Selvamanickam, V.; ORNL; SuperPower, Inc.

    2010-01-01

    Systematic effects of Zr additions on the structural and flux pinning properties of YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (YBCO) films deposited by metal-organic chemical vapor deposition (MOCVD) have been investigated. Detailed characterization, conducted by coordinated transport, x-ray diffraction, scanning and transmission electron microscopy analyses, and imaging Raman microscopy have revealed trends in the resulting property/performance correlations of these films with respect to varying mole percentages (mol%) of added Zr. For compositions {le} 7.5 mol%, Zr additions lead to improved in-field critical current density, as well as extra correlated pinning along the c-axis direction of the YBCO films via the formation of columnar, self-assembled stacks of BaZrO{sub 3} nanodots.

  10. Enhanced flux pinning in MOCVD-YBCO films through Zr additions: systematic feasibility studies

    International Nuclear Information System (INIS)

    Aytug, T; Paranthaman, M; Specht, E D; Zhang, Y; Kim, K; Zuev, Y L; Cantoni, C; Goyal, A; Christen, D K; Maroni, V A; Chen, Y; Selvamanickam, V

    2010-01-01

    Systematic effects of Zr additions on the structural and flux pinning properties of YBa 2 Cu 3 O 7-δ (YBCO) films deposited by metal-organic chemical vapor deposition (MOCVD) have been investigated. Detailed characterization, conducted by coordinated transport, x-ray diffraction, scanning and transmission electron microscopy analyses, and imaging Raman microscopy have revealed trends in the resulting property/performance correlations of these films with respect to varying mole percentages (mol%) of added Zr. For compositions ≤7.5 mol%, Zr additions lead to improved in-field critical current density, as well as extra correlated pinning along the c-axis direction of the YBCO films via the formation of columnar, self-assembled stacks of BaZrO 3 nanodots.

  11. Enhanced flux pinning in MOCVD-YBCO films through Zr additions: systematic feasibility studies

    Energy Technology Data Exchange (ETDEWEB)

    Aytug, T; Paranthaman, M; Specht, E D; Zhang, Y; Kim, K; Zuev, Y L; Cantoni, C; Goyal, A; Christen, D K [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Maroni, V A [Argonne National Laboratory, Argonne, IL 60439 (United States); Chen, Y; Selvamanickam, V, E-mail: aytugt@ornl.go [SuperPower, Incorporated, 450 Duane Avenue, Schenectady, NY 12304 (United States)

    2010-01-15

    Systematic effects of Zr additions on the structural and flux pinning properties of YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (YBCO) films deposited by metal-organic chemical vapor deposition (MOCVD) have been investigated. Detailed characterization, conducted by coordinated transport, x-ray diffraction, scanning and transmission electron microscopy analyses, and imaging Raman microscopy have revealed trends in the resulting property/performance correlations of these films with respect to varying mole percentages (mol%) of added Zr. For compositions {<=}7.5 mol%, Zr additions lead to improved in-field critical current density, as well as extra correlated pinning along the c-axis direction of the YBCO films via the formation of columnar, self-assembled stacks of BaZrO{sub 3} nanodots.

  12. The elastic limit of vortex movement in superconducting thin films

    International Nuclear Information System (INIS)

    Doyle, R.A.; Kumar, D.; Pullan, P.; Gross, R.; Campbell, A.M.; Blamire, M.G.; Somekh, R.E.; Evetts, J.E.

    1993-01-01

    Here we report four point ac transport FD measurements on epitaxial YBCO films and also polycrystalline NbTa films. Considerable efforts have recently been put into investigating low T c systems (11) in order to model high Tc materials in which the pinning and other properties are less easily controlled by microstructural modification and in which the parameter values are less well known. Moreover no reports exist of the FD behaviour of low T c thin film systems. In the case of the YBCO films, the results will be seen to be able to be reconciled with IP effects due to the superconducting CuO layers. In the case of the NbTa films, the results are in agreement with extrinsic pinning expected from the columnar defects (grain boundaries) observed in microstructural (SEM) studies (11). The data on all samples suggests core pinning in both (high Κ) systems. Features in the FD curves of the YBCO system when the field is carefully applied parallel to the planes occur at distances corresponding to the interlayer spacing providing direct evidence for IP. The technique also offers the possibility of investigating the frequency dependence of the effect as well as looking for curvature in the FD response below the onset of dissipation in the resistive component. The former study should be able to separate resistive from hysteretic (Bean) type losses whereas the latter might expose information about the shape of the pinning wells in addition to their sizes. These are discussed briefly here but will form the basis of further more detailed study. It will be argued that the FD technique is a powerful approach for investigation of the mixed state, allowing information to be extracted which is unavailable from other techniques. (orig.)

  13. Intermediate phase evolution in YBCO thin films grown by the TFA process

    International Nuclear Information System (INIS)

    Zalamova, K; Pomar, A; Palau, A; Puig, T; Obradors, X

    2010-01-01

    The YBCO thin film growth process from TFA precursors involves a complex reaction path which includes several oxide, fluoride and oxyfluoride intermediate phases, and the final microstructure and properties of the films are strongly influenced by the morphological and chemical evolution of these intermediate phases. In this work we present a study of the evolution of the intermediate phases involved in the TFA YBCO growth process under normal pressure conditions and we show that the oxygen partial pressure during pyrolysis of the TFA precursors is an important parameter. The Cu phase after the TFA pyrolysis can be either CuO, Cu 2 O or a mixture of both as the oxygen partial pressure is modified. The kinetics evolution of the intermediate phases has been determined for films pyrolysed in oxygen and nitrogen atmospheres and it is concluded that non-equilibrium phase transformations influence the reaction path towards epitaxial YBCO films and its microstructure. The intermediate phase evolution in these two series of films is summarized in kinetic phase diagrams.

  14. The growth and characterisation of YBa2Cu3O7-δ superconducting thin films

    International Nuclear Information System (INIS)

    McCurry, M.P.

    1999-02-01

    The normal state properties of YBa 2 Cu 3 O 7-δ (YBCO) are not completely understood. It is known that the oxygen doping play a large part in determining these properties. The optical conductivity of a series of c-axis YBCO thin films was investigated in this thesis. The films were grown on (100) MgO substrates using a pulsed laser deposition (PLD) system and characterised using X-ray diffraction, atomic force microscopy and resistance-temperature measurements. The optimum parameters for c-axis YBCO thin film growth were determined by systematically varying the main deposition parameters. The best quality films had a transition temperature T c ∼ 88K, with a transition width ∼ 1-2K. Critical current densities of J c ∼ 10 7 Acm -2 were obtained. Substrate and target morphology affected the quality of the films. a-axis YBCO films were grown using a PrBa 2 Cu 3 O 7 (PBCO) film as a template for growth. The choice of target and substrate were again important, with a smooth substrate essential for the multi-layering. T c ∼ 83K and J c ∼ 10 6 Acm -2 were the best values obtained. These values compare with data published on the 'best' YBCO films deposited by PLD. A series of c-axis films was controllably under-doped using an ex-situ annealing process. The as-grown films were assumed to be optimally doped with δ ∼ 0.05. Doping levels in the 'metallic' region, 0.05 -2 mbar. Another tetragonal film was obtained by cooling it after deposition in a nitrogen atmosphere. Neither had a superconducting transition; the c-axes of both films were elongated. The films could be successfully re-doped with oxygen, with a subsequent return to optimal values of T c and c-axis lattice parameter. The dielectric function of optimally doped and under-doped c-axis YBCO films was determined using the attenuated total reflection (ATR) technique. This data was obtained at a fixed frequency of 2984 cm -1 , (0.366eV), at temperatures ranging from 300K to 80K. The data was analysed in

  15. Dependence of critical current density on crystalline direction in thin YBCO films

    DEFF Research Database (Denmark)

    Paturi, P.; Peurla, M.; Raittila, J.

    2005-01-01

    The dependence of critical current density (J(c)) on the angle between the current direction and the (100) direction in the ab-plane of thin YBCO films deposited on (001)-SrTiO3 from natiocrystalline and microcrystalline targets is studied using magneto-optical microscopy. In the films made from...... the nanocrystalline target it is found that J(c) does not depend on the angle whereas J(c) decreases with increasing angle in the films made from the microcrystalline target. The films were characterized by detailed X-ray diffraction measurements. The findings are explained in terms of a network of planar defects...

  16. Enhanced flux pinning properties in superconducting YBa{sub 2}Cu{sub 3}O{sub 7−z} films by a novel chemical doping approach

    Energy Technology Data Exchange (ETDEWEB)

    Wang, W.T., E-mail: wtwang@swjtu.edu.cn [Key Laboratory of Magnetic Levitation and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Southwest Jiaotong University, Mail Stop 165, Chengdu, Sichuan 610031 (China); Pu, M.H.; Lei, M.; Zhang, H.; Wang, Z. [Key Laboratory of Magnetic Levitation and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Southwest Jiaotong University, Mail Stop 165, Chengdu, Sichuan 610031 (China); Zhang, H. [Department of Physics, Peking University, Beijing 100871 (China); Cheng, C.H. [Key Laboratory of Magnetic Levitation and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Southwest Jiaotong University, Mail Stop 165, Chengdu, Sichuan 610031 (China); Superconductivity Research Group, School of Materials Science and Engineering, University of New South Wale, Sydney, 2052 NSW (Australia); Zhao, Y., E-mail: yzhao@swjtu.edu.cn [Key Laboratory of Magnetic Levitation and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Southwest Jiaotong University, Mail Stop 165, Chengdu, Sichuan 610031 (China); Superconductivity Research Group, School of Materials Science and Engineering, University of New South Wale, Sydney, 2052 NSW (Australia)

    2013-10-15

    Highlights: • Pure and Co-doped YBCO films were prepared by newly-developed chemical method. • The doped films have much denser and smoother surface microstructures. • Significantly enhanced fux-pinning properties have been obtained for dilute Co-doped flm. -- Abstract: Pure and cobalt-doped superconducting YBa{sub 2}Cu{sub 3}O{sub 7−z} (YBCO) films were prepared on (0 0 l) LaAlO{sub 3} substrate by a newly developed polymer-assisted metal organic deposition method. The cobalt-doped YBCO films display much denser and smoother surface microstructures and the superconducting transition temperature T{sub c} spans a small range of 1.7 K with the doping levels. Significantly enhanced flux-pinning properties have been obtained for dilute cobalt-doped film. This may be attributed to the good grain connections and the effective flux pinning centers introduced by cobalt doping.

  17. Enhanced flux pinning properties in superconducting YBa2Cu3O7−z films by a novel chemical doping approach

    International Nuclear Information System (INIS)

    Wang, W.T.; Pu, M.H.; Lei, M.; Zhang, H.; Wang, Z.; Zhang, H.; Cheng, C.H.; Zhao, Y.

    2013-01-01

    Highlights: • Pure and Co-doped YBCO films were prepared by newly-developed chemical method. • The doped films have much denser and smoother surface microstructures. • Significantly enhanced fux-pinning properties have been obtained for dilute Co-doped flm. -- Abstract: Pure and cobalt-doped superconducting YBa 2 Cu 3 O 7−z (YBCO) films were prepared on (0 0 l) LaAlO 3 substrate by a newly developed polymer-assisted metal organic deposition method. The cobalt-doped YBCO films display much denser and smoother surface microstructures and the superconducting transition temperature T c spans a small range of 1.7 K with the doping levels. Significantly enhanced flux-pinning properties have been obtained for dilute cobalt-doped film. This may be attributed to the good grain connections and the effective flux pinning centers introduced by cobalt doping

  18. Response of thick-film bridge junction of high-Tc YBCO to nuclear radiation

    International Nuclear Information System (INIS)

    Ding Honglin; Wang Jun; Zhang Wanchang

    1992-01-01

    The response of thick-film Josephson junction based on high-T c YBCO to nuclear radiation is described. The lengths of the junction are 2000 μm, 1000 μm, and 500 μm and the widths are 500 μm, 300 μm and 100 μm. When the junction is irradiated by low energy γ-ray of 59.5 KeV from 241 Am at temperature of 77 K and the transport current I b is more than I c , the authors obtained the reduction of 1.6 mA of critical current and volt-signal as high as 17 μV without amplifier. It has been noted that the signal amplitude is related to the distance between the junction and the radiation source. Finally the advantages and shortcomings of detector based on thick films of high T c YBCO are discussed in the paper

  19. The mechanism of sputter-induced orientation change in YBCO films on MgO (001)

    International Nuclear Information System (INIS)

    Huang, Y.; Vuchic, B.V.; Baldo, P.; Merkle, K.L.; Buchholz, D.B.; Mahajan, S.; Lei, J.S.; Markworth, P.R.; Chang, R.P.H.

    1996-12-01

    The mechanisms of the sputter-induced orientation change in YBa 2 Cu 3 O 7-x (YBCO) films grown on MgO (001) substrates by pulsed organometallic beam epitaxy (POMBE) are investigated by x-ray diffraction. Rutherford backscatter spectroscopy (RBS), cross-section TEM (XTEM) and microanalysis. It is found that the W atom implantation concurring with the ion sputtering plays an important role in effecting the orientation change. This implantation changes the surface structure of the substrate and induces an intermediate layer in the initial growth of the YBCO film, which in turn acts as a template that induces the orientation change. It seems that the surface morphology change caused by ion sputtering has only a minor effect on the orientation change

  20. Imaging of current distributions in superconducting thin film structures

    International Nuclear Information System (INIS)

    Doenitz, D.

    2006-01-01

    Local analysis plays an important role in many fields of scientific research. However, imaging methods are not very common in the investigation of superconductors. For more than 20 years, Low Temperature Scanning Electron Microscopy (LTSEM) has been successfully used at the University of Tuebingen for studying of condensed matter phenomena, especially of superconductivity. In this thesis LTSEM was used for imaging current distributions in different superconducting thin film structures: - Imaging of current distributions in Josephson junctions with ferromagnetic interlayer, also known as SIFS junctions, showed inhomogeneous current transport over the junctions which directly led to an improvement in the fabrication process. An investigation of improved samples showed a very homogeneous current distribution without any trace of magnetic domains. Either such domains were not present or too small for imaging with the LTSEM. - An investigation of Nb/YBCO zigzag Josephson junctions yielded important information on signal formation in the LTSEM both for Josephson junctions in the short and in the long limit. Using a reference junction our signal formation model could be verified, thus confirming earlier results on short zigzag junctions. These results, which could be reproduced in this work, support the theory of d-wave symmetry in the superconducting order parameter of YBCO. Furthermore, investigations of the quasiparticle tunneling in the zigzag junctions showed the existence of Andreev bound states, which is another indication of the d-wave symmetry in YBCO. - The LTSEM study of Hot Electron Bolometers (HEB) allowed the first successful imaging of a stable 'Hot Spot', a self-heating region in HEB structures. Moreover, the electron beam was used to induce an - otherwise unstable - hot spot. Both investigations yielded information on the homogeneity of the samples. - An entirely new method of imaging the current distribution in superconducting interference devices

  1. Magnetoresistivity and Hall resistivity of a YBCO thin film in a tilted magnetic field

    International Nuclear Information System (INIS)

    Amirfeiz, M.; Cimberle, M. R.; Ferdeghini, C.; Giannini, E.; Grassano, G.; Marre', D.; Putti, M.; Siri, A. S.

    1997-01-01

    In this paper they present magnetoresistivity and Hall effect measurements performed on a YBCO epitaxial film as a function of the angle θ between the external magnetic field and the a-b planes. The resistivity and Hall effect measurements are analyzed in term of the general scaling approach proposed by Blatter and coworkers; the Hall conductivity data are examined to separate the contributions due to vortices and quasi particles

  2. Correlating properties and microstructure of YBCO thin films by magnetic X-ray microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ruoss, Stephen; Stahl, Claudia; Weigand, Markus; Schuetz, Gisela [Max-Planck-Institute for Intelligent Systems, Heisenbergstrasse 3, 70569 Stuttgart (Germany); Zahn, Patrick; Bayer, Jonas [Max-Planck-Institute for Intelligent Systems, Heisenbergstrasse 3, 70569 Stuttgart (Germany); Research Institute for Innovative Surfaces, FINO, Aalen University, Beethovenstrasse 1, 73430 Aalen (Germany); Albrecht, Joachim [Research Institute for Innovative Surfaces, FINO, Aalen University, Beethovenstrasse 1, 73430 Aalen (Germany)

    2016-07-01

    The magnetic flux distribution in high-temperature superconductors namely YBCO has been observed using a novel high-resolution technique based on the X-ray magnetic circular dichroism (XMCD). Therefore, a CoFeB layer is deposited on the superconductor which exhibits a strong XMCD-effect. X-ray absorption measurements with circular polarized radiation allows the analysis of the magnetic flux distribution in the superconductor via the soft-magnetic sensor layer [3,4]. In the total electron yield (TEY) mode of the scanning X-ray microscope (SXM) the surface structure and the magnetic domains can be imaged at the same time. Having obtained such high resolution images, the correlation of magnetic flux penetration and defect structure of YBCO thin films can be analyzed. The measurements have been performed at the scanning X-ray microscope MAXYMUS at Bessy II, HZB Berlin.

  3. High temperature superconducting films by rf magnetron sputtering

    International Nuclear Information System (INIS)

    Kadin, A.M.; Ballentine, P.H.

    1989-01-01

    The authors have produced sputtered films of Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O by rf magnetron sputtering from an oxide target consisting of loose reacted powder. The use of a large 8-inch stoichiometric target in the magnetron mode permits films located above the central region to be free of negative-ion resputtering effects, and hence yields reproducible, uniform stoichiometric compositions for a wide range of substrate temperatures. Superconducting YBCO films have been obtained either by sputtering at low temperatures followed by an 850 0 C oxygen anneal, or alternatively by depositing onto substrates heated to ∼600 - 650 0 C and cooling in oxygen. Films prepared by the former method on cubic zirconia substrate consist of randomly oriented crystallites with zero resistance above 83 K. Those deposited on zirconia at medium temperatures without the high-temperature anneal contain smooth partially oriented crystallites, with a slightly depressed T/sub c/ ∼75K. Finally, superconducting films have been deposited on MgO using a BiSrCaCu/sub 2/O/sub x/ powder target

  4. Properties of second phase (BaSnO3, Sn) added-YBCO thick films

    International Nuclear Information System (INIS)

    Ban, E.; Matsuoka, Y.

    1997-01-01

    The improvement of the critical current density J c of YBCO thick films has been attempted by adding BaSnO 3 powder and ultrafine Sn particles, whose diameter is about 2 μm and 7 x 10 -2 μm, respectively. It was found that the addition of a small amount of these particles was effective for the enhancement of J c of thick films prepared by a liquid-phase processing method. The 1 wt.% BaSnO 3 films fired at T s =1040-1060 C and the 3 wt.% Sn films (T s =1030-1060 C) showed J c values (77 K, 0 T) of about 2.1-2.4 x 10 3 Acm -2 and 3.1-3.5 x 10 3 Acm -2 , respectively, as compared to 2.0 x 10 3 Acm -2 for the undoped films. (orig.)

  5. Superconducting oxypnictide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Reisner, Andreas; Kidszun, Martin; Reich, Elke; Holzapfel, Bernhard; Schultz, Ludwig; Haindl, Silvia [IFW Dresden, Institute of Metallic Materials (Germany); Thersleff, Thomas [Uppsala University, Angstrom Laboratory (Sweden)

    2012-07-01

    We present an overview on the oxypnictide thin film preparation. So far, only LaAlO{sub 3} (001) single crystalline substrates provided a successful growth using pulsed laser deposition in combination with a post annealing process. Further experiments on the in-situ deposition will be reported. The structure of the films was investigated by X-ray diffractometry and transmission electron microscopy. Transport properties were measured with different applied fields to obtain a magnetic phase diagram for this new type of superconductor.

  6. Ba2NdZrO5.5 as a potential substrate material for YBa2Cu3O7-δ superconducting films

    International Nuclear Information System (INIS)

    Tovar, H.; Ortiz Diaz, O.; Landinez Tellez, D.A.; Roa-Rojas, J.

    2007-01-01

    The new oxide Ba 2 NdZrO 5.5 (BNZO) has been produced by the standard solid state reaction method. X-ray diffraction analysis (XRD) revealed that this synthesized material has an ordered complex cubic perovskite structure characteristic of A 2 BB'O 6 crystalline structure with a lattice parameter of a = 8.40 Aa. It was established through EDX analysis that there is no trace of impurities. Chemical stability of BNZO with YBa 2 Cu 3 O 7-δ (YBCO) has been studied by means of Rietveld analysis of experimental XRD data on several samples of BNZO-YBCO composites. Quantitative analysis of phases on XRD patterns show that all peaks have been indexed for both BNZO and YBCO, and no extra peak is detectable. YBCO and BNZO remain as two different separate phases in the composites with no chemical reaction. Electrical measurements also revealed that superconducting transition temperature of pure YBCO and BNZO-YBCO composites is 90 K. These favorable characteristics of BNZO show that it can be used as a potential substrate material for deposition of YBCO superconducting films. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. A low-fluorine solution with a 2:1 F/Ba mole ratio for the fabrication of YBCO films

    DEFF Research Database (Denmark)

    Wu, Wei; Feng, Feng; Yue, Zhao

    2014-01-01

    must be at least 2 for full conversion of the Ba-precursor to BaF2 to avoid the formation of BaCO3, which is detrimental to the superconducting performance of YBCO films. In this study, a solution with a 2:1 F/Ba mole ratio was developed, and the fluorine content of this solution was approximately only...... 10.3% of that used in the conventional TFA-MOD method. Attenuated total reflectance-Fourier transform-infrared spectra (ATR-FT-IR) revealed that BaCO3 was remarkably suppressed in the as-pyrolyzed film—and eliminated at 700 °C. Thus, YBCO films with a critical current density (Jc) of over 5 MA cm−2...... (77 K, 0 T, 200 nm thickness) could be obtained on lanthanum aluminate single-crystal substrates. In situ FT-IR spectra showed that no obvious fluorinated gaseous by-products were detected in the pyrolysis step, which indicated that all F atoms might remain in the film as fluorides. X-ray diffraction...

  8. Growth orientation and superconducting properties of YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} films prepared by the low-fluorine sol-gel process

    Energy Technology Data Exchange (ETDEWEB)

    Lei Li; Zhao Gaoyang; Xu Hui; Zhao Juanjuan, E-mail: leili813@gmail.co [School of Materials Science and Engineering, Xi' an University of Technology, Xi' an 710048 (China)

    2010-08-15

    YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (YBCO) films were deposited on (100)-oriented LaAlO{sub 3} (LAO) single crystal substrates by the dip-coating process using low-fluorine solution. Their microstructures were characterized with the aid of X-ray diffractometry, scanning electron microscopy and high-resolution transmission electron microscopy. Their superconducting properties were measured by the standard four-probe method. The experiment results show that the film obtained under high enough humidity conditions exhibits better c-axis texture and superconducting properties than the film under a relatively low humidity conditions. Based on the classical nucleation and chemical reaction thermodynamics theory, the underlying crystalline and growth mechanisms of YBCO films under certain humidity conditions are explained in combination with our experimental results. It is suggested that the unreacted intermediate phases such as BaF{sub 2} and CuO aggregated in the YBCO grain boundary will cause lattice distortion in the YBCO matrix and further induce the formation of a-axis oriented YBCO grains as crystallization proceeds. Therefore, it is believed that the relative content of water vapor within the heat-treatment atmosphere plays quite an important role in the preparation of c-axis oriented YBCO film with good superconducting properties. (semiconductor materials)

  9. Superconducting Generators for Airborne Applications and YBCO-Coated Conductors (Preprint)

    National Research Council Canada - National Science Library

    Barnes, Paul N; Levin, George A; Durkin, Edward B

    2008-01-01

    .... Superconducting generators can address this need. Recently, several successful rotating machinery projects demonstrated the practicality and feasibility of the technology using the high temperature superconducting BSCCO wire...

  10. Structural and superconducting characteristics of YBa2Cu3O7 films grown by fluorine-free metal-organic deposition route

    DEFF Research Database (Denmark)

    Zhao, Yue; Chu, Jingyuan; Qureishy, Thomas

    2018-01-01

    Microstructure and superconducting performance of YBa2Cu3O7 (YBCO) films deposited on LaAlO3 single crystal (LAO) substrates by a fluorine-free metal-organic deposition (FF-MOD) technique, have been studied by means of X-ray reciprocal space mapping (RSM), cross-sectional transmission electron mi...... external magnetic field at 77 K. This work offers an in-depth insight into the correlation between the microstructure and superconductivity in the MOD YBCO films.......Microstructure and superconducting performance of YBa2Cu3O7 (YBCO) films deposited on LaAlO3 single crystal (LAO) substrates by a fluorine-free metal-organic deposition (FF-MOD) technique, have been studied by means of X-ray reciprocal space mapping (RSM), cross-sectional transmission electron....... It is suggested that associated partial dislocations formed at the boundary between the stacking faults and YBCO matrix act as strong linear (or dot) pinning centers. These structural characteristics are well in line with the better superconducting performance of the low fluorine-MOD film, in particular under...

  11. A novel method of flat YBCO rings development for shield-type superconducting fault current limiters fabrication

    International Nuclear Information System (INIS)

    Hekmati, Arsalan; Hosseini, Mehdi; Vakilian, Mehdi; Fardmanesh, Mehdi

    2012-01-01

    A method has been proposed for flat YBCO ring Fabrication. A prototype SFCL with proposed design has been fabricated using the rings. J c characteristics of the rings are measured using an innovative method. The application of flat superconductor rings has been investigated in the structure of inductive shield-type high temperature superconducting fault current limiters, HT c -SFCL. A laboratory scale inductive shield-type HT c -SFCL has been designed and fabricated using flat superconductor rings. The fabrication process has been fully presented. YBCO powder has been used for the fabrication of superconductor rings. This fabrication process, being quite innovative, is introduced completely. The method of the trapped field measurement has been used for the critical current density measurement of the fabricated superconductor rings. The device with nominal current of 2 A was tested in a 30 V circuit. The SFCL successfully limited the fault currents of up to 10 times the nominal current to an approximately fixed value of 3 A. The voltage-current characteristic of the fabricated prototype has also been obtained and has shown compatibility with the fault current limitation results.

  12. Review of thin film superconductivity

    International Nuclear Information System (INIS)

    Kihlstrom, K.E.

    1989-01-01

    Advances in thin film superconductivity are critical to the success of many proposed applications. The authors review several of the prominent techniques currently used to produce thin films of the high temperature superconductors including electron beam co-deposition, sputtering (both multiple and composite source configurations) and laser ablation. The authors look at the relevant parameters for each and evaluate the advantages and disadvantages of each technique. In addition, promising work on in situ oxidation is discussed. Also addressed are efforts to find optimum substrate materials and substrate buffer layers for various applications. The current state of the art for T c , J c and H c2 is presented for the yttrium, bismuth, and thallium compounds

  13. Positron annihilation study on the superconductivity of Gd-doped YBCO system

    International Nuclear Information System (INIS)

    Chen Zhenping; Su Yuling; Xue Yuncai; Liu Haizeng; Gong Shicheng; Zhao Jingxun; Li Xigui

    2006-01-01

    To make clear the influence of magnetic rare-earth ion Gd 3+ doping in the Y site on crystal structure and localized electron structure of YBCO system, the Gd-doped Y 1-x Gd x Ba 2 Cu 3 O 7-δ (x=0-1.0) systems were studied systematically by the positron annihilation technique and X-ray diffraction (XRD). The XRD analysis reveals that Gd 3+ with bigger radius doping in Y site makes the crystal parameters and crystal volume increase, while all the samples remain the single orthorhombic phase as YBa 2 Cu 3 O 7-δ (YBCO) system does. The temperature dependence of resistance measurement shows that T c is above 90 K for all samples, and T c increases with increasing Gd 3+ content. The positron experiment indicates that the localized electronic density n e decreases with increasing Gd 3+ content. (authors)

  14. Thermodynamical fluctuations and critical behavior in weakly disordered YBCO thin and ultra-thin films

    International Nuclear Information System (INIS)

    Lesueur, J.; Aprili, M.; Degoy, S.; Chambonnet, D.; Keller, D.

    1996-01-01

    The specific role of disorder in the transport properties of YBCO has been investigated, using both light-ion irradiation of thin films to finely tune the amount of atomic disorder, and ultra-thin films grown to study possible dimensional effects. For weak disorder, the samples display a resistive transition typical of the mean-field paraconductive regime of a homogeneous media, well described by the Lawrence and Doniach model for layered superconductors. As the disorder increases, two effects take place. First, the c-axis coherence length becomes shorter, leading to a more anisotropic material, as shown by the excess conductivity above T c . Second, an incipient granularity is revealed, leading to a less sharper transition, which is analyzed within the random 3D XY critical model for the paracoherence transition. Two main results are derived: an experimental test of the Ginzburg criteria for the paracoherence transition, and a new fluctuation regime in nanometric grain size superconductors

  15. Influence of initial pH on the microstructure of YBa2Cu3O7−x superconducting thin films derived from DEA-aqueous sol–gel method

    DEFF Research Database (Denmark)

    Xiao, Tang; Yue, Zhao; Grivel, Jean-Claude

    2013-01-01

    A fluorine-free aqueous sol–gel technique was used to fabricate YBCO superconducting thin films. Acetic acid was added in order to modify the complexation process taking place between the metal cations and the organic chelating agents. The electrical resistance and the pH value were used as indic......A fluorine-free aqueous sol–gel technique was used to fabricate YBCO superconducting thin films. Acetic acid was added in order to modify the complexation process taking place between the metal cations and the organic chelating agents. The electrical resistance and the pH value were used...

  16. High critical current density YBCO films and fabrication of dc-SQUIDs

    CERN Document Server

    Kuriki, S; Kawaguchi, Y; Matsuda, M; Otowa, T

    2002-01-01

    In order to improve the sensitivity of SQUID magnetometers made of high-T sub c films, we have studied the conditions of pulsed-laser deposition of YBCO films. Among the different deposition parameters examined, extensive degassing of the vacuum chamber before and precise control of the substrate temperature during the film deposition were found effective for obtaining high critical temperature T sub c and high critical current density J sub c. It was also found that the residual-resistance ratio has a clear correlation with J sub c , indicating that it can be a good, and easy to measure, index of the film quality. Films having T sub c approx 89-90 K and J sub c >= 5x10 sup 6 A cm sup - sup 2 at 77 K were used to fabricate SQUIDs without a pickup loop. Grain-boundary junctions formed on bicrystal substrates with a 30 deg. misorientation angle exhibited I sub c R sub n values of more than 100 mu V at 77 K. The well-known scaling behaviour of the relation I sub c R sub n propor to (J sup G sup B sub c) sup 1 su...

  17. Formation and physical properties of YBCO thick films grown by using the electrophoretic deposition method

    CERN Document Server

    Kim, U J; Kim, Y C; Han, S K; Kang, K Y

    1999-01-01

    Thick films of the YBa sub 2 Cu sub 3 O subgamma sub - subdelta (YBCO) superconductor were prepared by using the electrophoretic deposition technique and a flexible wire as the substrate. The transition temperature of the wires was 91 K, the intragranular magnetic critical current density J sub c sub g sup m sup a sup g was about 10 sup 5 A/cm sup 2 at 77 K in a weak field, and the transport J sub c sup t sup r sup a sup n sup s was about 365 A/cm sup 2 at 77 K. We calculated the intergranular magnetic critical current J sub c sub J sup m sup a sup g and the activation energy from the AC-susceptibility measurements, and their values were about 444 A/cm sup 2 at 77 K and 2.02 eV, respectively.

  18. Fabrication of thick superconducting films by decantation

    Directory of Open Access Journals (Sweden)

    Julián Betancourt M.

    1991-07-01

    Full Text Available We have found superconducting behavior in thick films fabricated by decantation. In this paper we present the experimental method and results obtained using commercial copper substrates.

  19. In-plane aligned YBCO film on textured YSZ buffer layer deposited on NiCr alloy tape by laser ablation with only O+ ion beam assistance

    International Nuclear Information System (INIS)

    Xin Tang Huang

    2000-01-01

    High critical current density and in-plane aligned YBa 2 Cu 3 O 7-x (YBCO) film on a textured yttria-stabilized zirconia (YSZ) buffer layer deposited on NiCr alloy (Hastelloy c-275) tape by laser ablation with only O + ion beam assistance was fabricated. The values of the x-ray phi-scan full width at half-maximum (FWHM) for YSZ(202) and YBCO(103) are 18 deg. and 11 deg., respectively. The critical current density of YBCO film is 7.9 x 105 A cm -2 at liquid nitrogen temperature and zero field, and its critical temperature is 90 K. (author)

  20. Disorder and fluctuations in superconducting YBa2Cu3O6.9 films

    International Nuclear Information System (INIS)

    Gauzzi, A.

    1993-01-01

    We have developed the technique of ion-beam sputtering to grow thin (∼ 100 nm) superconducting YBa 2 Cu 3 O 6.9 (YBCO) films. We demonstrate that this technique is suitable for the in-situ deposition at low temperatures ( o C) of uniform films over large areas (≤30 cm 2 ). We found that preferential sputtering effects disappear if low-power ions-beams are used, thus enabling the control of the 1:2:3 composition by using a single stoichiometric target. We have found that the disorder in the crystal, introduced by too high or too low growth temperatures, affects strikingly both, the superconducting and the transport properties of the films. We report evidence that disorder on the atomic scale plays a role equivalent to oxygen doping. The similarity observed between the effects of crystal disorder in our films and the effects of oxygen depletion or Co-doping reported in the literature suggests that the disorder affects mainly the CuO chains. This implies that the local order of the chains controls not only the superconducting properties, as already established in the literature, but also the transport of the carriers in the normal state. Finally, we have investigated the local character of the superconducting state of YBCO by studying the paraconductivity in our films. We have found no indication of critical fluctuations at temperatures ≥5 mK above the zero-resistance critical temperature. Our analysis indicates that the spectrum of mean-field fluctuations is dominated by short-wavelength components and is affected by disorder. As a consequence, the temperature dependence of the critical exponents becomes complex and deviates from the universal predictions of conventional theories. We have explained quantitatively our experimental data and clarified the controversy existing in the literature by using a three-dimensional cut-off approach applied to the Lorentzian spectrum of the Ginzburg-Landau theory. (author) figs., tabs., refs

  1. Epitaxial YBa2Cu3O7 films on rolled-textured metals for high temperature superconducting applications

    International Nuclear Information System (INIS)

    Norton, D.P.; Park, C.; Prouteau, C.

    1998-04-01

    The epitaxial growth of high temperature superconducting (HTS) films on rolled-textured metal represents a viable approach for long-length superconducting tapes. Epitaxial, 0.5 microm thick YBa 2 Cu 3 O 7 (YBCO) films with critical current densities, J c , greater than 1 MA/cm 2 have been realized on rolled-textured (001) Ni tapes with yttria-stabilized zirconia (YSZ)/CeO 2 oxide buffer layers. This paper describes the synthesis using pulsed-laser deposition (PLD) of epitaxial oxide buffer layers on biaxially-textured metal that comprise the so-called rolling-assisted biaxially-textured substrates (RABiTs trademark). The properties of the buffer and YBa 2 Cu 3 O 7 films on rolled-textured Ni are discussed, with emphasis given to the crystallographic and microstructural properties that determine the superconducting properties of these multilayer structures

  2. Effect of the microscopic correlated-pinning landscape on the macroscopic critical current density in YBCO films

    Science.gov (United States)

    Ghigo, G.; Chiodoni, A.; Gerbaldo, R.; Gozzelino, L.; Laviano, F.; Mezzetti, E.; Minetti, B.; Camerlingo, C.

    This paper deals with the mechanisms controlling the critical current density vs. field behavior in YBCO films. We base our analysis on a suitable model concerning the existence of a network of intergrain Josephson junctions whose length is modulated by defects. Irradiation with 0.25 GeV Au ions provide a useful tool to check the texture of the sample, in particular to give a gauge length reference to separate “weak” links and high- J c links.

  3. Properties of HTS YBCO thin films deposited on tilted NdGaO{sub 3} substrates

    Energy Technology Data Exchange (ETDEWEB)

    Nurgaliev, T. [Laboratory of Superconductivity and Cryoelectronics, Institute of Electronics BAS, 72 Tsarigradsko Chausse, 1784 Sofia (Bulgaria)]. E-mail: timur@ie.bas.bg; Donchev, T. [Laboratory of Superconductivity and Cryoelectronics, Institute of Electronics BAS, 72 Tsarigradsko Chausse, 1784 Sofia (Bulgaria); Mateev, E. [Laboratory of Superconductivity and Cryoelectronics, Institute of Electronics BAS, 72 Tsarigradsko Chausse, 1784 Sofia (Bulgaria); Miteva, S. [Laboratory of Superconductivity and Cryoelectronics, Institute of Electronics BAS, 72 Tsarigradsko Chausse, 1784 Sofia (Bulgaria); Mozhaev, P.B. [Institute of Physics and Technology RAS, Nakhimovsky Ave. 36, 117218 Moscow (Russian Federation); Mozhaeva, J.E. [Institute of Physics and Technology RAS, Nakhimovsky Ave. 36, 117218 Moscow (Russian Federation)

    2005-03-15

    Thin YBa{sub 2}Cu{sub 3}O{sub 7} films were fabricated by 2-opposed DC magnetron sputtering onto NdGaO{sub 3} substrates, tilted from standard (1 1 0) orientation by 0-26 deg , and their surface morphology and electrical characteristics were investigated. Normal state resistivity (at 295 K) and microwave surface resistance (at 77 K and {approx}8 GHz) of the films demonstrated anisotropy, introduced by the tilted substrate, and some improvement of the superconducting parameters of the films was observed at small tilt angles ({theta} {approx} 1.5-3 deg ). The increase of the microwave surface resistance at high tilt angles for the current tracks, perpendicular to the steps of the substrate, was described in the framework of a simple model, which takes into account the complex conductivity of the film and the weak links between the film terraces.

  4. Properties of HTS YBCO thin films deposited on tilted NdGaO3 substrates

    International Nuclear Information System (INIS)

    Nurgaliev, T.; Donchev, T.; Mateev, E.; Miteva, S.; Mozhaev, P.B.; Mozhaeva, J.E.

    2005-01-01

    Thin YBa 2 Cu 3 O 7 films were fabricated by 2-opposed DC magnetron sputtering onto NdGaO 3 substrates, tilted from standard (1 1 0) orientation by 0-26 deg , and their surface morphology and electrical characteristics were investigated. Normal state resistivity (at 295 K) and microwave surface resistance (at 77 K and ∼8 GHz) of the films demonstrated anisotropy, introduced by the tilted substrate, and some improvement of the superconducting parameters of the films was observed at small tilt angles (θ ∼ 1.5-3 deg ). The increase of the microwave surface resistance at high tilt angles for the current tracks, perpendicular to the steps of the substrate, was described in the framework of a simple model, which takes into account the complex conductivity of the film and the weak links between the film terraces

  5. Epitaxial growth and superconducting properties of YBa23Cu3O7 thin films and YBa2Cu3O7/Dy(Pr)Ba2Cu3O7 superlattices

    International Nuclear Information System (INIS)

    Triscone, J.M.; Brunner, O.; Antognazza, L.; Kent, A.D.; Fischer, O.; Karkut, M.G.

    1990-01-01

    The authors have prepared in situ REBa 2 Cu 3 O 7 (REBCO) (RE = Y, Pr, Dy) thin films and YBCO/Dy(Pr)BCO superlattices by single target dc planar magnetron sputtering. YBCO/DyBCO superlattices have been realized with modulation wavelength as short as 24 Angstrom, i.e., a unit cell of YBCO alternates with a unit cell of DyBCO, on average. The superconducting properties of such superlattices are indistinguishable from those of single layers. T co 's (zero resistance) are between 85 and 89K, and the residual resistivity ratios are between 2.5 and 3. In contrast to these results, when YBCO is layered with PrBCO, which is insulating, a dramatic change in the superconducting properties is observed. The authors have been able to artificially vary the coupling between single 12 Angstrom unit cell of YBCO by interposing insulating planes of PrBCO. As the YBCO layer separation increases, T c is reduced and the transition broadens showing evidence of 2-D superconducting fluctuations

  6. Microwave effective surface impedance of structures including a high-Tc superconducting film

    International Nuclear Information System (INIS)

    Hartemann, P.

    1992-01-01

    The microwave effective surface impedances of different stacks made of high-temperature superconducting films, dielectric materials and bulk normal metals were computed. The calculations were based on the two-fluid model of superconductors and the conventional transmission line theory. These effective impedances are compared to the calculated intrinsic surface impedances of the stacked superconducting films. The considered superconducting material has been the oxide YBa 2 Cu 3 O 7 epitaxially grown on crystalline substrates (MgO, LaAlO 3 , SrTiO 3 ), the film thickness ranging from a few nm to 1μm. Discrepancies between the effective surface resistances or reactances and the corresponding intrinsic values were determined at 10 GHz for non resonant or resonant structures. At resonance the surface resistance discrepancy exhibits a sharp peak which reaches 10 4 or more in relative value according to the geometry and the used materials. Obviously the effective surface reactance shows also huge variations about the resonance and may be negative. Moreover geometries allowing to obtain an effective resistance smaller than the film intrinsic value have been found. The effects of the resonance phenomenon on the electromagnetic wave reflectivity and reflection phase shift are investigated. Therefore the reported theoretical results demonstrate that the effective surface impedance of YBCO films with a thickness smaller than 500 nm can be very different from the intrinsic film impedance according to the structures. (Author). 3 refs., 10 figs., 2 tabs

  7. Magnetic response and critical current properties of mesoscopic-size YBCO superconducting samples

    International Nuclear Information System (INIS)

    Lisboa-Filho, P N; Deimling, C V; Ortiz, W A

    2010-01-01

    In this contribution superconducting specimens of YBa 2 Cu 3 O 7-δ were synthesized by a modified polymeric precursor method, yielding a ceramic powder with particles of mesoscopic-size. Samples of this powder were then pressed into pellets and sintered under different conditions. The critical current density was analyzed by isothermal AC-susceptibility measurements as a function of the excitation field, as well as with isothermal DC-magnetization runs at different values of the applied field. Relevant features of the magnetic response could be associated to the microstructure of the specimens and, in particular, to the superconducting intra- and intergranular critical current properties.

  8. Magnetic response and critical current properties of mesoscopic-size YBCO superconducting samples

    Energy Technology Data Exchange (ETDEWEB)

    Lisboa-Filho, P N [UNESP - Universidade Estadual Paulista, Grupo de Materiais Avancados, Departamento de Fisica, Bauru (Brazil); Deimling, C V; Ortiz, W A, E-mail: plisboa@fc.unesp.b [Grupo de Supercondutividade e Magnetismo, Departamento de Fisica, Universidade Federal de Sao Carlos, Sao Carlos (Brazil)

    2010-01-15

    In this contribution superconducting specimens of YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} were synthesized by a modified polymeric precursor method, yielding a ceramic powder with particles of mesoscopic-size. Samples of this powder were then pressed into pellets and sintered under different conditions. The critical current density was analyzed by isothermal AC-susceptibility measurements as a function of the excitation field, as well as with isothermal DC-magnetization runs at different values of the applied field. Relevant features of the magnetic response could be associated to the microstructure of the specimens and, in particular, to the superconducting intra- and intergranular critical current properties.

  9. Greatly enhanced flux pinning properties of fluorine-free metal-organic decomposition YBCO films by co-addition of halogens (Cl, Br) and metals (Zr, Sn, Hf)

    Science.gov (United States)

    Motoki, Takanori; Ikeda, Shuhei; Nakamura, Shin-ichi; Honda, Genki; Nagaishi, Tatsuoki; Doi, Toshiya; Shimoyama, Jun-ichi

    2018-04-01

    Additive-free YBCO films, as well as those with halogen (X) added, metal (M) added and (X, M) co-added, have been prepared by the fluorine-free metal-organic decomposition method on SrTiO3(100) single crystalline substrates, where X = Cl, Br and M = Zr, Sn, Hf. It was revealed that the addition of both Cl and Br to the starting solution resulted in the generation of oxyhalide, Ba2Cu3O4 X 2, in the YBCO films, and that the oxyhalide was found to promote the bi-axial orientation of the YBCO crystals. By adding a decent amount of Cl or Br, highly textured YBCO films with high J c were reproducibly obtained, even when an impurity metal, M, was co-added, while the addition of M without X did not greatly improve J c owing to the poor bi-axial orientation of the YBCO crystals. Our results suggest that the addition of Br more effectively enhances J c than the addition of Cl. The pinning force density at 40 K in 4.8 T reached ˜55 GN m-3 with the co-addition of (Br, M). This value is much larger than that of the pure YBCO film, reaching ˜17 GN m-3.

  10. Thermal propagation and stability in superconducting films

    International Nuclear Information System (INIS)

    Gray, K.E.; Kampwirth, R.T.; Zasadzinski, J.F.; Ducharme, S.P.

    1983-01-01

    Thermal propagation and stable hot spots (normal domains) are studied in various high Tsub(c) superconducting films (Nb 3 Sn, Nb, NbN and Nb 3 Ge). A new energy balance is shown to give reasonable quantitative agreement of the dependence of the propagation velocity on the length of short normal domains. The steady state (zero velocity) measurements indicate the existence of two distinct situations for films on high thermal conductivity (sapphire) substrates. For low power per unit area the film and substrate have the same temperature, and the thermal properties of the substrate dominate. However, for higher power densities in short hot spots, the coupling is relatively weak and the thermal properties of the film alone are important. Here a connection is made between the critical current stability of superconducting films and a critical hot spot size for thermal propagation. As a result efficient heat removal is shown to dominate the stabilisation of superconducting films. The strong and weak coupling situations also lead to modifications of the models for propagation velocities on sapphire substrates. Self-healing of hot spots and other phenomena in superconducting film are explained. The potential use of the thermal propagation model in applications of superconductors, especially switches is discussed. (author)

  11. Spray pyrolysis process for preparing superconductive films

    International Nuclear Information System (INIS)

    Hsu, H.M.; Yee, I.Y.

    1991-01-01

    This paper describes a spray pyrolysis method for preparing thin superconductive film. It comprises: preparing a spray pyrolysis solution comprising Bi,Sr,Ca and Cu metals in a solvent; heating a substrate to a first temperature; spraying the solution onto the heated substrate to form a film thereon; heating the film and substrate to a second temperature of about 700 degrees-825 degrees C, the second temperature being higher than the first temperature; heating the film and substrate to a third temperature of about 870 degrees-890 degrees C to melt the film; once the film and substrate reach the third temperature, further heat treating the film and substrate; cooling the film and substrate to ambient temperature. This patent also describes a spray pyrolysis method for preparing thin superconductive films. It comprises: preparing a spray pyrolysis solution comprising Bi, Ca and Cu metals and fluxing agent in a solvent; heating a substrate to a first temperature; spraying the solution onto the heated substrate to form a film thereon; heating the film and substrate to a second temperature about 700 degrees-825 degrees C, the second temperature being higher than the first temperature; heating the film and substrate at a third temperature about 840 degrees-860 degrees C; and cooling the film and substrate to ambient temperature

  12. Superconducting Generators for Airborne Applications and YBCO-Coated Conductors (Preprint)

    Science.gov (United States)

    2008-10-01

    design was a homopolar inductor alternator (HIA) which locates the superconductor coil within the stator, thereby eliminating rotational loads on the...advantages over the BSCCO tape previous used in motor and generator demonstrations. The benefits of compact high- power superconducting machinery

  13. Microstructure and superconducting properties of YBCO bulk superconductors with RE substitutions

    Czech Academy of Sciences Publication Activity Database

    Volochová, D.; Antal, V.; Piovarči, S.; Kováč, J.; Jirsa, Miloš; Noudem, J.; Diko, P.

    2016-01-01

    Roč. 26, č. 3 (2016), s. 1-4, č. článku 7200604. ISSN 1051-8223 Institutional support: RVO:68378271 Keywords : yttrium barium copper oxide * critical current density (superconductivity) * powders * magnetic fields * microstructure * temperature measurement Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.092, year: 2015

  14. Use of high-temperature superconducting films in superconducting bearings

    International Nuclear Information System (INIS)

    Cansiz, A.

    1999-01-01

    We have investigated the effect of high-temperature superconductor (HTS) films deposited on substrates that are placed above bulk HTSs in an attempt to reduce rotational drag in superconducting bearings composed of a permanent magnet levitated above the film/bulk HTS combination. According to the critical state model, hysteresis energy loss is inversely proportional to critical current density, J c , and because HTS films typically have much higher J c than that of bulk HTS, the film/bulk combination was expected to reduce rotational losses by at least one order of magnitude in the coefficient of fiction, which in turn is a measure of the hysteresis losses. We measured rotational losses of a superconducting bearing in a vacuum chamber and compared the losses with and without a film present. The experimental results showed that contrary to expectation, the rotational losses are increased by the film. These results are discussed in terms of flux drag through the film, as well as of the critical state model

  15. Switching, storage, and erasure effects in a superconducting thin film

    International Nuclear Information System (INIS)

    Testardi, L.R.

    1976-01-01

    Thin niobium films can be switched from a superconducting to a resistive state permanently by application of a short electrical pulse. Application of a short pulse of opposite polarity returns the film to the superconducting state

  16. Laser patterning of superconducting oxide films

    International Nuclear Information System (INIS)

    Gupta, A.; Hussey, B.W.; Koren, G.; Cooper, E.I.; Jagannathan, R.

    1988-01-01

    The focused output of an argon ion laser (514.5 nm) has been used for wiring superconducting lines of Y/sub 1/Ba/sub 2/CU/sub 3/O/sub 7-δ/ using films prepared from nitrate and trifluoroacetate solution precursors. A stoichiometric solution of the precursors is sprayed or spun on to the substrate to form a film. The film is patterned by irradiating in selected areas to convert the irradiated layers to an intermediate oxide or fluoride state, the nonirradiated areas being unchanged. The nonirradiated areas are then dissolved away, leaving a pattern of the oxide or fluoride material. This patterned layer is converted to the superconducting 1-2-3 oxide in a subsequent annealing step. Maskless patterning of superconducting films has also been demonstrated by laser-assisted etching of the films in aqueous KOH solution. Although superconductivity is destroyed when the films are placed in solution, it can be restored after a brief anneal in oxygen

  17. Defining B-c, B* and B-phi for YBCO Thin Films

    DEFF Research Database (Denmark)

    Paturi, Petriina; Irjala, Matti; Abrahamsen, Asger Bech

    2009-01-01

    of superconducting films. Similarly, the characteristic field, B c, can be obtained from magneto-optical (MO) images from when the flux fronts meet in the middle of the film. The matching field, B phi, at which there is one vortex line per pinning site, is sometimes thought to be the same as B*, but in BaZrO3-doped...... YBa2Cu3O7 films the calculated B phi is much higher than the observed B*. B phi can be determined from angular dependent transport measurements. All of the field values correspond to some special case in the flux pinning in the film and relate to J c. In this work we have determined B c, B* and B phi...

  18. Two Magnon Raman Scattering as Indicator for Superconducting to Antiferromagnetic Phase Transition Upon Hydrogenation of YBCO

    International Nuclear Information System (INIS)

    Biton, Y.; Shuker, R.

    1999-01-01

    Raman spectra of Hydrogenated YBa 2 Cu 3 O 7-x + H y , where y = 0.45 and 0.19 is the number of Hydrogen atoms per units cell. The spectra exhibit important changes in the electronic scattering. Upon progressive doping with Hydrogen two magnon scattering features emerge. This coincides with the transition of YBa 2 Cu 3 O 7x +H y from superconducting to antiferromagnetic phase. Exchange energy values were obtained from two magnon Raman scattering of the y = 0.45 material. It has been found that for y= 0.19 the sample has not lost its superconductivity, and indeed two-magnon scattering has not been observed. However, the situation changed substantially when the doping of the Hydrogen atoms was 0.45. The two-magnon scattering has been observed at different temperatures down to 20K. The two-magnon energy density exhibits two peak values around 2100cm -1 and 3000cm -1

  19. Improved interface growth and enhanced flux pinning in YBCO films deposited on an advanced IBAD-MgO based template

    Science.gov (United States)

    Khan, M. Z.; Zhao, Y.; Wu, X.; Malmivirta, M.; Huhtinen, H.; Paturi, P.

    2018-02-01

    The growth mechanism is studied from the flux pinning point of view in small-scale YBa2Cu3O6+x (YBCO) thin films deposited on a polycrystalline hastelloy with advanced IBAD-MgO based buffer layer architecture. When compared the situation with YBCO films grown on single crystal substrates, the most critical issues that affect the suitable defect formation and thus the optimal vortex pinning landscape, have been studied as a function of the growth temperature and the film thickness evolution. We can conclude that the best critical current property in a wide applied magnetic field range is observed in films grown at relatively low temperature and having intermediate thickness. These phenomena are linked to the combination of the improved interface growth, to the film thickness related crystalline relaxation and to the formation of linear array of edge dislocations that forms the low-angle grain boundaries through the entire film thickness and thus improve the vortex pinning properties. Hence, the optimized buffer layer structure proved to be particularly suitable for new coated conductor solutions.

  20. A comparative study on the flux pinning properties of Zr-doped YBCO film with those of Sn-doped one prepared by metal-organic deposition

    International Nuclear Information System (INIS)

    Choi, S. M.; Shin, G. M.; Joo, Y.S.; Yoo, S. I.

    2013-01-01

    We investigated the flux pinning properties of both 10 mol% Zr-and Sn-doped YBa 2 Cu 3 O 7-δ (YBCO) films with the same thickness of ∽350 nm for a comparative purpose. The films were prepared on the SrTiO 3 (STO) single crystal substrate by the metal-organic deposition (MOD) process. Compared with Sn-doped YBCO film, Zr-doped one exhibited a significant enhancement in the critical current density (J c ) and pinning force density (F p ). The anisotropic J c ,min/J c ,max ratio in the field-angle dependence of J c at 77 K for 1 T was also improved from 0.23 for Sn-doped YBCO to 0.39 for Zr-doped YBCO. Thus, the highest magnetic J c values of 9.0 and 2.9 MA/cm 2 with the maximum F p (F p ,max) values of 19 and 5 GN/m 3 at 65 and 77 K for H // c, respectively, could be achieved from Zr-doped YBCO film. The stronger pinning effect in Zr-doped YBCO film is attributable to smaller BaZrO-3 (BZO) nanoparticles (the average size ≈ 28.4 nm) than YBa 2 SnO 5. 5 (YBSO) nanoparticles (the average size ≈ 45.0 nm) incorporated in Sn-doped YBCO film since smaller nanoparticles can generate more defects acting as effective flux pinning sites due to larger incoherent interfacial area for the same doping concentration.

  1. Tailoring the vortex pinning strength of YBCO thin films by systematic incorporation of hybrid artificial pinning centers

    International Nuclear Information System (INIS)

    Jha, Alok K; Matsumoto, Kaname; Horide, Tomoya; Saini, Shrikant; Mele, Paolo; Ichinose, Ataru; Yoshida, Yutaka; Awaji, Satoshi

    2015-01-01

    The effect of hybrid (columnar and spherical together) artificial pinning centers (APCs) on the vortex pinning properties of YBa 2 Cu 3 O 7−δ (YBCO) thin films is investigated in detail on the basis of variation of critical current density (J C ) with applied magnetic field and also with the orientation of the applied magnetic field at 65 K and 77 K. Premixed YBCO + BaSnO 3 composite targets are used for the deposition of the YBCO films which consist of self-assembled BaSnO 3 nanocolumns (1D APCs); on the other hand, for the deposition of the YBCO films with hybrid APCs (BaSnO 3 nanocolumns together with Y 2 O 3 nanoparticles), the surface of the premixed YBCO + BaSnO 3 composite targets are modified by putting a thin Y 2 O 3 sectored piece on the premixed YBCO + BaSnO 3 composite targets by means of silver paste. F pmax value increases systematically with incorporation of 1D and 1D and 3D APCs and it also shifts towards higher applied magnetic fields. Films with 1D APCs exhibit a strong J C peak at Θ = 0° (H//c-axis) whereas films consisting of hybrid APCs exhibit enhanced J C at all the investigated angular regimes. A possible mechanism of vortex pinning in samples with hybrid APCs is also discussed suggesting the role of 1D and 3D APCs. (paper)

  2. Preparation of SmBCO layer for the surface optimization of GdYBCO film by MOCVD process based on a simple self-heating technology

    Science.gov (United States)

    Zhao, Ruipeng; Zhang, Fei; Liu, Qing; Xia, Yudong; Lu, Yuming; Cai, Chuanbing; Tao, Bowan; Li, Yanrong

    2018-07-01

    The MOCVD process was adopted to grow the REBa2Cu3O7-δ ((REBCO), RE = rare earth elements) films on the LaMnO3 (LMO) templates. Meanwhile, the LMO-template tapes are heated by the joule effect after applying a heating current through the Hastelloy metal substrates. The surface of GdYBCO films prepared by MOCVD method is prone to form outgrowths. So the surface morphology of GdYBCO film is optimized by depositing the SmBCO layer, which is an important process method for the preparation of high-quality multilayer REBCO films. At last, the GdYBCO/SmBCO/GdYBCO multilayer films were successfully prepared on the LMO templates based on the simple self-heating method. It is demonstrated that the GdYBCO surface was well improved by the characterization analysis of scanning electron microscope. And the Δω of REBCO (005) and Δφ of REBCO (103), which were performed by an X-ray diffraction system, are respectively 1.3° and 3.3° What's more, the critical current density (Jc) has been more than 3 MA/cm2 (77 K, 0 T) and the critical current (Ic) basically shows a trend of good linear increase with the increase of the number of REBCO layers.

  3. Application of textured YBCO bulks with artificial holes for superconducting magnetic bearing

    International Nuclear Information System (INIS)

    Dias, D H N; Sotelo, G G; Moysés, L A; Telles, L G T; Bernstein, P; Aburas, M; Noudem, J G; Kenfaui, D; Chaud, X

    2015-01-01

    The levitation force between a superconductor and a permanent magnet has been investigated for the development of superconducting magnetic bearings (SMBs). Depending on the proposed application, the SMBs can be arranged with two kinds of symmetries: rotational or linear. The SMBs present passive operation, low level of noise and no friction, but they need a cooling system for their operation. Nowadays the cooling problem may be easily solved by the use of a commercial cryocooler. The levitation force of SMBs is directly related to the quality of the superconductor material (which depends on its critical current density) and the permanent magnet arrangement. Also, research about the YBa 2 Cu 3 O x (Y123) bulk materials has shown that artificial holes enhance the superconducting properties, in particular the magnetic trapped field. In this context, this work proposes the investigation of the levitation force of a bulk Y123 sample with multiple holes and the comparison of its performances with those of conventional plain Y123 superconductors. (paper)

  4. Imaging of current distributions in superconducting thin film structures; Abbildung von Stromverteilungen in supraleitenden Duennfilmstrukturen

    Energy Technology Data Exchange (ETDEWEB)

    Doenitz, D.

    2006-10-31

    Local analysis plays an important role in many fields of scientific research. However, imaging methods are not very common in the investigation of superconductors. For more than 20 years, Low Temperature Scanning Electron Microscopy (LTSEM) has been successfully used at the University of Tuebingen for studying of condensed matter phenomena, especially of superconductivity. In this thesis LTSEM was used for imaging current distributions in different superconducting thin film structures: - Imaging of current distributions in Josephson junctions with ferromagnetic interlayer, also known as SIFS junctions, showed inhomogeneous current transport over the junctions which directly led to an improvement in the fabrication process. An investigation of improved samples showed a very homogeneous current distribution without any trace of magnetic domains. Either such domains were not present or too small for imaging with the LTSEM. - An investigation of Nb/YBCO zigzag Josephson junctions yielded important information on signal formation in the LTSEM both for Josephson junctions in the short and in the long limit. Using a reference junction our signal formation model could be verified, thus confirming earlier results on short zigzag junctions. These results, which could be reproduced in this work, support the theory of d-wave symmetry in the superconducting order parameter of YBCO. Furthermore, investigations of the quasiparticle tunneling in the zigzag junctions showed the existence of Andreev bound states, which is another indication of the d-wave symmetry in YBCO. - The LTSEM study of Hot Electron Bolometers (HEB) allowed the first successful imaging of a stable 'Hot Spot', a self-heating region in HEB structures. Moreover, the electron beam was used to induce an - otherwise unstable - hot spot. Both investigations yielded information on the homogeneity of the samples. - An entirely new method of imaging the current distribution in superconducting interference

  5. Magnetization Controlled Superconductivity in a Film with Magnetic Dots

    International Nuclear Information System (INIS)

    Lyuksyutov, I.F.; Pokrovsky, V.; Pokrovsky, V.

    1998-01-01

    We consider a superconducting film with a magnetic dots array (MDA) placed upon it. Magnetic moments of the dots are normal to the film and strong enough to create vortices in the superconducting film. Magnetic interaction between dots is negligible. Zero-field cooling leads to random magnetization of the MDA well above the superconducting temperature. With this cooling, the film is in a resistive state below the (expected) superconducting transition. Paradoxically, when field cooled, the film with MDA can be superconducting. copyright 1998 The American Physical Society

  6. Excessive current in wide superconducting films

    International Nuclear Information System (INIS)

    Volotskaya, V.G.; Sivakov, A.G.; Turutanov, O.G.

    1986-01-01

    The resistive state of a wide long film due to superconductivity destruction by current is studied. The voltage-independent excess current I 0 is observed on I-V curves at high transport currents. The two-dimensional image of the current-carrying sample obtained by laser scanning technique in this current range indicates that the whole film is in the resistive state. The current I 0 is measured as a function of magnetic field and SHF power

  7. Enhancement of YBCO thin film thermal stability under 1 ATM oxygen pressure by Intermediate Cu.sub.2./sub. O nanolayer

    Czech Academy of Sciences Publication Activity Database

    Cheng, L.; Wang, X.; Yao, X.; Wan, W.; Li, F.H.; Xiong, J.; Tao, B.W.; Jirsa, Miloš

    2010-01-01

    Roč. 114, č. 22 (2010), s. 7543-7547 ISSN 1520-6106 R&D Projects: GA MŠk(CZ) ME10069 Institutional research plan: CEZ:AV0Z10100520 Keywords : YBCO thin films * thermal stability * thin film growth orientation * temperature optical microscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.603, year: 2010

  8. Relations between structural and superconducting properties of bulk and thin film high-Tc materials

    International Nuclear Information System (INIS)

    Hessel Andersen, N.

    1994-06-01

    The structural ordering of oxygen deficient and Co-doped YBCO (YBa 2 Cu 3-y Co y O 6+x ) have been studied experimentally, and by computer simulations of the oxygen ordering in the basal plane of the structure. The calculations are based on the two-dimensional ASYNNNI model and its modifications. Good agreement is established between the ASYNNNI calculations and the experimentally observed structural properties of the double cell ortho-II structure and the oxygen disordering process from Co-doping into the basal plane. A model that relates the superconducting transition temperature T c (x) of undoped YBCO and T c (y) of Co-doped YBCO to the formation of specific domains of the two orthorhombic ordered oxygen phases, ortho-I and ortho-II, shows a close agreement with experimental T c (x) and T c (y) data of samples prepared under equilibrium conditions. The structural changes as a result of metal ion substitutions and oxidation/reduction processes have been studied by neutron powder diffraction in Pb 2 Sr 2 Ln 1-x Ca x Cu 3 O 8+y (Ln = Y and Ho), Nd 1.85 Ce 0.15 CuO 4+y , and chemically oxidized La 2-x Sr x CuO 4+y 2 Cu 3-y Al y O 6+x (y 2 Cu 3 O 6+x and Bi 2 Sr 2 CaCu 2 O 8+x thin films deposited on SrTiO 3 (001), MgO (001), LaAlO 3 (001), and NdGaO 3 (001) substrates has been studied by x-ray diffraction, TEM and RBS, and the structural ordering has been analysed in relation to their superconducting properties. (au) (30 ills., 29 refs.)

  9. Gold nanocrystals in high-temperature superconducting films: Creation of pinning patterns of choice

    Energy Technology Data Exchange (ETDEWEB)

    Katzer, Christian; Michalowski, Peter; Schmidl, Frank; Seidel, Paul [Institut fuer Festkoerperphysik, Friedrich-Schiller-Universitaet Jena, 07743 Jena (Germany); Stahl, Claudia; Treiber, Sebastian; Schuetz, Gisela [Max-Planck-Institut fuer Intelligente Systeme, Heisenbergstrasse 3, 70569 Stuttgart (Germany); Christiani, Georg [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, 70569 Stuttgart (Germany); Albrecht, Joachim [Hochschule Aalen, Beethovenstrasse 1, 73430 Aalen (Germany)

    2013-07-01

    Many superconducting thin film devices require a spatially resolved current carrying capability due to different boundary conditions. On the one hand, the critical current density and the pinning of flux lines respectively should be high to reduce flux noise in the antenna regions of gradiometers; on the other hand, the critical current density of the Josephson junctions itself must not be too high to ensure a proper functionality. We report that adding gold nanoparticles during the preparation process of epitaxial YBa{sub 2}Cu{sub 3}O{sub 7-δ} thin films offers the possibility of creating spatially varying flux pinning properties, thus allowing to locally enhance the critical current density up to a factor of two. Magneto-optical investigations as well as transport measurements will be presented, indicating that an Au particle induced modification of the YBCO pinning properties allows the engineering of the critical current landscape on the sub-micrometre scale.

  10. Geometrical resonance effects in thin superconducting films

    International Nuclear Information System (INIS)

    Nedellec, P.

    1977-01-01

    Electron tunneling density of states measurements on thick and clear superconducting films (S 1 ) backed by films in the normal or superconducting state (S 2 ) show geometrical resonance effects associated with the spatial variation of Δ(x), the pair potential, near the interface S 1 -S 2 . The present understanding of this so-called 'Tomasch effect' is described. The dispersion relation and the nature of excitations in the superconducting state are introduced. It is shown that the introduction of Green functions give a general description of the superconducting state. The notion of Andreev scattering at the S 1 -S 2 interface is presented and connect the geometrical resonance effects to interference process between excitations. The different physical parameters involved are defined and used in the discussion of some experimental results: the variation of the period in energy with the superconducting thickness is connected to the renormalized group velocity of excitations traveling perpendicular to the film. The role of the barrier potential at the interface on the Tomasch effect is described. The main results discussed are: the decrease of the amplitude of the Tomasch structures with energy is due to the loss of the mixed electron-hole character of the superconducting excitations far away from the Fermi level; the variation of the pair potential at the interface is directly related to the amplitude of the oscillations; the tunneling selectivity is an important parameter as the amplitude as well as the phase of the oscillations are modified depending on the value of the selectivity; the phase of the Tomasch oscillations is different for an abrupt change of Δ at the interface and for a smooth variation. An ambiguity arises due to the interplay between these parameters. Finally, some experiments, which illustrate clearly the predicted effects are described [fr

  11. Microstructures and precipitates in laser-ablated YBCO thin films on SrTiO[sub 3] (110). [Y-Ba-Cu-O

    Energy Technology Data Exchange (ETDEWEB)

    Catana, A. (IBM Research Div., Zurich Research Lab., Rueschlikon (Switzerland)); Rossel, C. (IBM Research Div., Zurich Research Lab., Rueschlikon (Switzerland)); Perrin, A. (Lab. de Chimie du Solide et Inorganique Moleculaire, Univ. de Rennes 1, 35 (France)); Guilloux-Viry, M. (Lab. de Chimie du Solide et Inorganique Moleculaire, Univ. de Rennes 1, 35 (France)); Thivet, C. (Lab. de Chimie du Solide et Inorganique Moleculaire, Univ. de Rennes 1, 35 (France))

    1993-05-10

    Thin YBCO films ([proportional to] 100 nm) have been deposited by laser ablation on SrTiO[sub 3] (110) substrates. Microstructural investigations have been performed by scanning tunneling and high-resolution electron microscopy. The results show that the surface corrugation is related to the growth of twisted YBCO domains that nucleate at the film/substrate interface. The twist is characterized by a 90 rotation of YBCO around the 100 and/or 010 axes, which results in [l brace]013[r brace] and/or [l brace]103[r brace] planes parallel to the substrate surface. Precipitates belonging to Y[sub 2]O[sub 3] are densely distributed on the film surface. No such second phases have been identified inside the YBCO films. The orientational relationship between precipitates and film is such that the lattice mismatch is minimized in the interface planes. A large number of precipitates grow from the film surface outwards. This phenomenon can be explained on the basis of lattice matching arguments and favorable growth kinetics. (orig.)

  12. Sequential Ar-O2 sputtering of Y2O3, BaF2, and CuO targets for preparation of Y-Ba-Cu-O superconducting films without wet-O2 annealing

    International Nuclear Information System (INIS)

    Bhushan, M.; Strauss, A.J.; Finn, M.C.

    1989-01-01

    Superconducting Y-Ba-Cu-O (YBCO) films have been prepared by ex situ O 2 annealing of multilayer films deposited on yttria-stabilized zirconia substrates by sequential rf diode sputtering of Y 2 O 3 , BaF 2 , and CuO targets, all of which are chemically stable. If sputtering is performed in an Ar ambient, the as-deposited films contain sufficient F to require its removal by annealing in wet O 2 at about 800 degree C or above before the superconducting YBCO phase can be formed by annealing in dry O 2 . However, sputtering in an Ar-O 2 ambient greatly reduces the F content, making it possible to obtain the superconducting phase by annealing in dry O 2 only. If the ambient contains about 20% O 2 , films with T c (R=0)>85 K can be prepared without wet-O 2 annealing. The Ar-O 2 process therefore has the potential for in situ preparation of superconducting YBCO films

  13. Ferromagnetic film on a superconducting substrate

    Energy Technology Data Exchange (ETDEWEB)

    Bulaevskii, L. N.; Chudnovsky, E. M.

    2001-01-01

    We study the equilibrium domain structure and magnetic flux around a ferromagnetic film with perpendicular magnetization M{sub 0} on a superconducting (SC) substrate. At 4{pi}M{sub 0}film, l, scales as (l/4{pi}{lambda}{sub L})=(l{sub N}/4{pi}{lambda}{sub L}){sup 2/3} with the domain width on a normal (nonsuperconducting) substrate, l{sub N}/4{pi}{lambda}{sub L}>>1; {lambda}{sub L} being the London penetration length.

  14. Ferromagnetic film on a superconducting substrate

    International Nuclear Information System (INIS)

    Bulaevskii, L. N.; Chudnovsky, E. M.

    2001-01-01

    We study the equilibrium domain structure and magnetic flux around a ferromagnetic film with perpendicular magnetization M 0 on a superconducting (SC) substrate. At 4πM 0 c1 the SC is in the Meissner state and the equilibrium domain width in the film, l, scales as (l/4πλ L )=(l N /4πλ L ) 2/3 with the domain width on a normal (nonsuperconducting) substrate, l N /4πλ L >>1; λ L being the London penetration length

  15. Analysis of influence of buffer layers on microwave propagation through high-temperature superconducting thin films

    International Nuclear Information System (INIS)

    Ceremuga, J.; Barton, M.; Miranda, F.

    1994-01-01

    Methods of analysis of microwave propagation through superconducting thin films with buffer layers on dielectric substrates have been discussed. Expressions describing the transmission coefficient S 21 through the structure and the complex conductivity sigma of a superconductor in an analytical form have been derived. The derived equations are valid for microwave propagation in waveguides as well as in free space with relevant definition of impedances. Using the obtained solutions, the influences of buffer layers' parameters (thickness, relative permittivity and loss tangent) on the transmission coefficient has been investigated using MATLAB. Simulations have been performed for 10 GHz transmission through YBa 2 Cu 3 O 7 films on sapphire with SrTiO 3 and CeO 2 buffer layers and on silicon with CaF 2 and YSZ buffer layers. To illustrate the simulations, measurements of the transmission through YBCO film on sapphire with SrTiO 3 buffer layer have been performed. It has been shown that even lossy buffer layers have very little impact (smaller than 1% in magnitude and 0.3% in phase) on the transmission coefficient through superconducting thin films, providing their thickness is below 10 mu m. (author)

  16. Superconducting films of YBaCuO

    International Nuclear Information System (INIS)

    Coelho, A.L.

    1991-01-01

    Thick films of YBa 2 Cu 3 O 7 - x have been prepared on alumina and YSZ (Yttria-stabilized zirconia) substrates by the screen printing technique. Several experimental conditions have been studied, for instance: sintering time, temperature, thickness and atmosphere annealed. The resulting films have been characterized by X-ray diffraction, AC electrical resistance, AC susceptibility and scanning electron microscopy. The surface and cross-section have been observed with an optical microscope. The X-ray diffraction patterns have been compared with a typical pattern and that has indicated the good quality of the samples. AC resistance and its temperature dependence have been measured in the standard four-probe configuration. Films thickness has been estimated in the scanning electron microscope. This technique has been suitable for production of high T c superconducting films being a simple and inexpensive method. (author)

  17. AC over-current characteristics of YBCO coated conductor with copper stabilizer layer considering insulation layer

    International Nuclear Information System (INIS)

    Du, H.-I.; Kim, M.-J.; Kim, Y.-J.; Lee, D.-H.; Han, B.-S.; Song, S.-S.

    2010-01-01

    Compared with the first-generation BSCCO wire, the YBCO thin-film wire boasts low material costs and high J c and superior magnetic-field properties, among other strengths. Meanwhile, the previous BSCCO wire material for superconducting cables has been researched on considerably with regard to its post-wire quenching characteristics during the application of an alternating over-current. In this regard, the promising YBCO thin-film wire has yet to be further researched on. Moreover, still lacking is research on the YBCO thin-film wire with insulating layers, which is essential in the manufacture of superconducting cables, along with the testing of the application of an alternating over-current to the wire. In this study, YBCO thin-film wires with copper-stabilizing layers were used in testing alternating over-current application according to the presence or absence of insulating layers and to the thickness of such layers, to examine the post-quenching wire resistance increase and quenching trends. The YBCO thin-film wire with copper-stabilizing layers has a critical temperature of 90 K and a critical current of 85 A rms . Moreover, its current application cycle is 5.5 cycles, and its applied currents are 354, 517, 712, and 915 A peak . These figures enabled the YBCO thin-film wires with copper-stabilizing layers to reach 90, 180, 250, and 300 K, respectively, in this study. These temperatures serve as a relative reference to examine the post-quenching wire properties following the application of an alternating over-current.

  18. Rapid processing method for solution deposited YBa2Cu3O7-δ thin films

    International Nuclear Information System (INIS)

    Dawley, J.T.; Clem, P.G.; Boyle, T.J.; Ottley, L.M.; Overmyer, D.L.; Siegal, M.P.

    2004-01-01

    YBa 2 Cu 3 O 7-δ (YBCO) films, deposited on buffered metal substrates, are the primary candidate for second-generation superconducting (SC) wires, with applications including expanded power grid transmission capability, compact motors, and enhanced sensitivity magnetic resonance imaging. Feasibility of manufacturing such superconducting wires is dependent on high processing speed, often a limitation of vapor and solution-based YBCO deposition processes. In this work, YBCO films were fabricated via a new diethanolamine-modified trifluoroacetic film solution deposition method. Modifying the copper chemistry of the YBCO precursor solution with diethanolamine enables a hundredfold decrease in the organic pyrolysis time required for MA/cm 2 current density (J c ) YBCO films, from multiple hours to ∼20 s in atmospheric pressure air. High quality, ∼0.2 μm thick YBCO films with J c (77 K) values ≥2 MA/cm 2 at 77 K are routinely crystallized from these rapidly pyrolyzed films deposited on LaAlO 3 . This process has also enabled J c (77 K)=1.1 MA/cm 2 YBCO films via 90 m/h dip-coating on Oak Ridge National Laboratory RABiTS textured metal tape substrates. This new YBCO solution deposition method suggests a route toward inexpensive and commercializable ∼$10/kA m solution deposited YBCO coated conductor wires

  19. Superconductivity in disordered thin films

    International Nuclear Information System (INIS)

    Ramakrishnan, T.V.

    1989-01-01

    The physics of low-dimensional systems has developed in a remarkable way over the last decade and has accelerated over the last few years, in particular because of the discovery of the new high temperature superconductors. The new developments started more than fifteen years ago with the discovery of the unexpected quasi-one-dimensional character of the TTF-TCNQ. Since then the field of conducting quasi-one-dimensional organic system have been rapidly growing. Parallel to the experimental work there has been an important theoretical development of great conceptual importance, such as charge density waves, soliton-like excitations, fractional charges, new symmetry properties etc. A new field of fundamental importance was the discovery of the Quantum Hall Effect in 1980. This field is still expanding with new experimental and theoretical discoveries. In 1986, then, came the totally unexpected discovery of high temperature superconductivity which started an explosive development. The three areas just mentioned formed the main themes of the Symposium. They do not in any way exhaust the progress in low-dimensional physics. We should mention the recent important development with both two-dimensional and one-dimensional and even zero-dimensional structures (quantum dots). The physics of mesoscopic systems is another important area where the low dimensionality is a key feature. Because of the small format of this Symposium we could unfortunately not cover these areas

  20. Development of YBCO tape conductor fabrication technology

    Energy Technology Data Exchange (ETDEWEB)

    Hong, G W; Kim, C J; Lee, H G. and others

    2001-08-01

    Superconductor when fabricated into wire shape is applied for developing electric power transmission cable, transformer, generator and SMES. Such superconducting power devices are capable of maximizing the efficiency of electricity and are anticipated to contribute for solving the energy problem of humankind. Furthermore the high temperature oxide superconductor developed in late 1980s is superconducting above boiling temperature of liquid nitrogen temperature has strong potential to realize superconducting power device and a lot of researches are being done in this field. Superconducting wire is the most important core material for developing superconducting power device and thermo-mechanical powder in tube process was developed to fabricated Ag/Bi-2223 conductor in long length having high critical current carrying capacity. Several companies fabricate and sell Ag/Bi-2223 superconducting wire longer than km length and used for developed electrical power device. But because of its inherent property of sharp decrease in current carrying capacity when applying high magnetic field, the application of Bi-2223 sire is limited as low as 20 K when the power device is in operating under high magnetic field. The YBCO tape conductor has the advantages of maintaining high critical current applying high magnetic field and can be used to most of the power device without special limitation. The metal substrate having good crystallographic texture and deposition technique which can deposit the good quality superconducting thin film continuously in large area are need to fabricate coated conductor, and this technique can be applied to develop the superconducting current limiter or magnetic field shielding device. A superconducting wire for using in high magnetic field is play a critical role in developing maglev, MRI, SMES, transformer, generator and motor and the continuous film deposition technique can be applied in other industry very much.

  1. Influence of Sm2O3 microalloying and Yb contamination on Y211 particles coarsening and superconducting properties of IG YBCO bulk superconductors

    Science.gov (United States)

    Vojtkova, L.; Diko, P.; Kovac, J.; Vojtko, M.

    2018-06-01

    Single grain YBa2Cu3O7‑x (YBCO or Y123) bulk superconductors were produced by an infiltration growth process. The solid phase precursor was prepared by solid state synthesis from Y2O3 + BaCuO2 powders. The influence of the addition of Sm2O3 and YB contamination from the substrate on the microstructure and superconducting properties was analyzed. The dependences of Yb concentration on the distance from the bottom of the samples measured by energy dispersive spectroscopy microanalysis used in conjunction with scanning electron microscopy confirmed the contamination of the samples during the melting stage of the sample preparation. It is shown that the addition of Sm in low concentration and its combination with Yb from the substrate modify the coarsening of the Y211 particles as well as lead to the appearance of a secondary peak effect in the field dependences of the critical current density.

  2. Ferromagnetic Film on a Superconducting Substrate

    OpenAIRE

    Bulaevskii, L. N.; Chudnovsky, E. M.

    2000-01-01

    We study the equilibrium domain structure and magnetic flux around a ferromagnetic (FM) film with perpendicular magnetization M_0 on a superconducting (SC) substrate. At 4{\\pi}M_0> 1. Here \\lambda_L is the London penetration length. For 4{\\pi}M_0 > H_{c1} and l_{N} in excess of about 35 {\\lambda}_{L}, the domains are connected by SC vortices. We argue that pinning of vortices by magnetic domains in FM/SC multilayers can provide high critical currents.

  3. Critical currents in multilayered superconducting films

    International Nuclear Information System (INIS)

    Raffy, Helene

    1977-01-01

    The superconducting critical currents Isub(c) were measured as a function of magnetic field H and temperature T, on multilayered films. These films consist of alternating layers of two different superconductors S 1 and S 2 being a weaker superconductor acting as a flux pinning barrier region. A strong anisotropy was observed between the two situations where the magnetic field H is applied parallel or perpendicular to the layers. In the case discussed, there is a peak effect in the curves Isub(c)H well defined at the highest temperatures, and disappearing at low temperatures. The anisotropy of the critical current at constant field presents a maximum at a temperature T* close to the critical temperature Tsub(c 2 ) of S 2 [fr

  4. Rapid processing method for solution deposited YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Dawley, J.T.; Clem, P.G.; Boyle, T.J.; Ottley, L.M.; Overmyer, D.L.; Siegal, M.P

    2004-02-01

    YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (YBCO) films, deposited on buffered metal substrates, are the primary candidate for second-generation superconducting (SC) wires, with applications including expanded power grid transmission capability, compact motors, and enhanced sensitivity magnetic resonance imaging. Feasibility of manufacturing such superconducting wires is dependent on high processing speed, often a limitation of vapor and solution-based YBCO deposition processes. In this work, YBCO films were fabricated via a new diethanolamine-modified trifluoroacetic film solution deposition method. Modifying the copper chemistry of the YBCO precursor solution with diethanolamine enables a hundredfold decrease in the organic pyrolysis time required for MA/cm{sup 2} current density (J{sub c}) YBCO films, from multiple hours to {approx}20 s in atmospheric pressure air. High quality, {approx}0.2 {mu}m thick YBCO films with J{sub c} (77 K) values {>=}2 MA/cm{sup 2} at 77 K are routinely crystallized from these rapidly pyrolyzed films deposited on LaAlO{sub 3}. This process has also enabled J{sub c} (77 K)=1.1 MA/cm{sup 2} YBCO films via 90 m/h dip-coating on Oak Ridge National Laboratory RABiTS textured metal tape substrates. This new YBCO solution deposition method suggests a route toward inexpensive and commercializable {approx}$10/kA m solution deposited YBCO coated conductor wires.

  5. Superconducting properties of iron chalcogenide thin films

    Directory of Open Access Journals (Sweden)

    Paolo Mele

    2012-01-01

    Full Text Available Iron chalcogenides, binary FeSe, FeTe and ternary FeTexSe1−x, FeTexS1−x and FeTe:Ox, are the simplest compounds amongst the recently discovered iron-based superconductors. Thin films of iron chalcogenides present many attractive features that are covered in this review, such as: (i easy fabrication and epitaxial growth on common single-crystal substrates; (ii strong enhancement of superconducting transition temperature with respect to the bulk parent compounds (in FeTe0.5Se0.5, zero-resistance transition temperature Tc0bulk = 13.5 K, but Tc0film = 19 K on LaAlO3 substrate; (iii high critical current density (Jc ~ 0.5 ×106 A cm2 at 4.2 K and 0 T for FeTe0.5Se0.5 film deposited on CaF2, and similar values on flexible metallic substrates (Hastelloy tapes buffered by ion-beam assisted deposition with a weak dependence on magnetic field; (iv high upper critical field (~50 T for FeTe0.5Se0.5, Bc2(0, with a low anisotropy, γ ~ 2. These highlights explain why thin films of iron chalcogenides have been widely studied in recent years and are considered as promising materials for applications requiring high magnetic fields (20–50 T and low temperatures (2–10 K.

  6. Materials for superconducting cavities

    International Nuclear Information System (INIS)

    Bonin, B.

    1996-01-01

    The ideal material for superconducting cavities should exhibit a high critical temperature, a high critical field, and, above all, a low surface resistance. Unfortunately, these requirements can be conflicting and a compromise has to be found. To date, most superconducting cavities for accelerators are made of niobium. The reasons for this choice are discussed. Thin films of other materials such as NbN, Nb 3 Sn, or even YBCO compounds can also be envisaged and are presently investigated in various laboratories. It is shown that their success will depend critically on the crystalline perfection of these films. (author)

  7. Anisotrophic currents and flux jumps in high-Tc superconducting films with self-organized arrays of planar defects

    International Nuclear Information System (INIS)

    Yurchenko, V.V.; Qviller, A.J.; Mozhaev, P.B.; Mozhaeva, J.E.; Hansen, J.B.; Jacobsen, C.S.; Kotelyanskii, I.M.; Pan, A.V.; Johansen, T.H.

    2010-01-01

    Regular arrays of planar defects with a period of a few nanometers can be introduced in superconducting YBa 2 Cu 3 O 7-δ (YBCO) thin films by depositing them on vicinal (also called miscut or tilted) substrates. This results in the anisotropy of critical currents flowing in the plane of the film. We present results of real-time magneto-optical imaging (MOI) of magnetic flux distribution and dynamics in a series of YBCO thin films deposited on NdGaO 3 substrates with different miscut angles θ. MOI allows reconstructing the current flow profiles. From the angle formed between domains with different directions of the current flow we determine the anisotropy parameter of the in-plane current, as well as its field and temperature dependences. The artificially introduced defects also have a dramatic effect on the dynamics of the flux propagation: for 10 o o the magnetic flux propagates along the easy channels intermittently, i.e. in a form of flux jumps. This behavior is indicative of thermo-magnetic instability in superconductors, but we argue that this effect can be of a different nature.

  8. Disappearance of superconductivity and critical resistance in thin indium films

    International Nuclear Information System (INIS)

    Okuma, Satoshi; Nishida, Nobuhiko

    1991-01-01

    In thin granular films composed of two-dimensionally coupled indium particles, we have studied influences of average particle sizes anti d on the superconducting transition. For films with anti d=280A and 224A, superconducting transition temperature stays almost constant with increasing the sheet resistance R n in the normal state, while for a film with anti d=140A, it decreases linearly with R n . This means that the system changes to a dirty superconductor by reducing anti d. With further increasing R n , superconductivity disappears when R n exceeds the value R c of order h/4e 2 , which seems to correlate with anti d. (orig.)

  9. High trapped fields in bulk YBCO superconductors

    Science.gov (United States)

    Fuchs, Günter; Gruss, Stefan; Krabbes, Gernot; Schätzle, Peter; Verges, Peter; Müller, Karl-Hartmut; Fink, Jörg; Schultz, Ludwig

    The trapped field properties of bulk melt-textured YBCO material were investigated at different temperatures. In the temperature range of liquid nitrogen, maximum trapped fields of 1.1 T were found at 77 K by doping of YBCO with small amounts of zinc. The improved pinning of zinc-doped YBa2Cu3O7-x (YBCO) results in a pronounced peak effect in the field dependence of the critical current density. the trapped field at lower temperatures increases due to the increasing critical current density, however, at temperatures around 50 K cracking of the material is observed which is exposed to considerably tensile stresses due to Lorentz forces. Very high trapped fields up to 14.4 T were achieved at 22.5 K for a YBCO disk pair by the addition of silver improving the tensile strength of YBCO and by using a bandage made of a steel tube. The steel tube produces a compressive stress on YBCO after cooling down from 300 K to the measuring temperature, which is due to the higher coeeficient of thermal expansion of steel compared with that of YBCO in the a,b plane. The application of superconducting permanent magnets with trapped fields of 10 T and more in superconducting bearings would allow to obtain very high levitation pressures up to 2500 N/cm2 which is two orders of magnitude higher than the levitation pressure achievable in superconducting bearings with conventional permanent magnets. The most important problem for the application of superconducting permanent magnets is the magnetizing procedure of the YBCO material. Results of magnetizing YBCO disks by using of pulsed magnetic fields will be presented.

  10. Fluctuation conductivity of thin superconductive vanadium films

    International Nuclear Information System (INIS)

    Dmitrenko, I.M.; Sidorenko, A.S.; Fogel, N.Y.

    1982-01-01

    Resistive transitions into the superconductive state are studied in thin [d >T/sub c/ the experimental data on the excess conductivity of the films agree qualitatively and quantitively with Aslamazov--Larkin theory. There is no Maki--Thompson contribution to fluctuation conductivity. Near T/sub c/ the excess conductivity sigma' changes exponentially with temperature in accordance with the predictions of the theory of the critical fluctuations of the order parameter. The values of the effective charge carrier mass defined from data on sigma' for the low fluctuation and critical fluctuation regions differ markedly. This difference is within the spread of effective masses for various charge carrier groups already known for vanadium. Causes of the difference in resistive behavior for the regions T >T/sub c/ are considered

  11. A pinning puzzle: two similar, non-superconducting chemical deposits in YBCO-one pins, the other does not

    Energy Technology Data Exchange (ETDEWEB)

    Sawh, Ravi-Persad; Weinstein, Roy; Gandini, Alberto; Skorpenske, Harley; Parks, Drew, E-mail: Weinstein@uh.ed [Beam Particle Dynamics Laboratories, University of Houston, Houston, TX 77204-5005 (United States); Department of Physics, University of Houston, Houston, TX 77204-5005 (United States); Texas Center for Superconductivity at UH, University of Houston, Houston, TX 77204-5002 (United States)

    2009-09-15

    The pinning effects of two kinds of U-rich deposits in YBCO (YBa{sub 2}Cu{sub 3}O{sub 7-{delta}}) are compared. One is a five-element compound, (U{sub 0.6}Pt{sub 0.4})YBa{sub 2}O{sub 6}, which is a paramagnetic double perovskite which forms as profuse stable nanosize deposits, and pins very well. The other is a four-element compound, (U{sub 0.4}Y{sub 0.6})BaO{sub 3}, which is a ferromagnetic single perovskite which forms as profuse stable nanosize deposits and pins very weakly or not at all. The pinning comparison is done with nearly equal deposit sizes and number of deposits per unit volume for the two compounds. Evidence for the pinning capability, chemical makeup, x-ray diffraction signature, and magnetic properties of the two compounds is reported.

  12. Reproducible synthesis of YBCO high-temperature superconducting ceramics (step 1) and parameters and optimized design of superconducting Magnetic Bearings (step 2). Final report

    International Nuclear Information System (INIS)

    Floegel-Delor, U.; Rothfeld, R.; Wippich, D.; Werfel, F.

    1999-11-01

    A method for selective and economically efficient production of large HTSL bodies on the basis of polycrystalline YBCO material (CCG - CeramoCrystalGrowth) was developed which does not require nucleation and achieves macroscopic grain orientation and high intrinsic current densities of 30 A/cm (intrinsic field). Formed bodies up to a diameter of 150 mm and a mass of 2 kg were grown. In the second stage, frictionless and contactless magnetic bearings with HTS were investigated. They were found to have advantages over the current technologies, e.g. extremely high speed and bearing of unbalanced rotors [de

  13. Comment on ``Ferromagnetic film on a superconducting substrate''

    Science.gov (United States)

    Sonin, E. B.

    2002-10-01

    A superconducting substrate is not able to shrink drastically domains in a ferromagnetic film, contrary to the prediction of Bulaevskii and Chudnovsky. This is shown on the basis of the exact solution for the stripe domain structure.

  14. Properties of superconducting thin-film microbridges

    International Nuclear Information System (INIS)

    Pei, S.S.

    1978-01-01

    This work reports investigations upon the dependences of critical current and current phase relation on the dimensions of a superconducting thin-film microbridge. A model has been developed upon the Volkov's hyperbolic bridges and the Zaitsev's boundary conditions to calculate the spatial variation of the order parameter for given bridge dimensions. The results indicate that the rigid boundary conditions are good approximations to narrow bridges (W much less than L) only. The critical current density of the bridge has been calculated also as a function of the bridge dimensions. It is found that the critical current density of small bridges is enhanced above its mean field critical value due to the proximity effects of the banks. Very good agreement is found between the calculated enhancement of the critical current density and the experimental results. Direct measurements have been made on the current phase relation of indium bridges with width smaller than 0.6 μm. The difficulties due to the extra phase shifts from the series thin film electrodes are overcome by a specially designed double loop configuration which has an extra low effective inductance. It is found that the current phase relation of small bridges (W,L, xi, the results agree with the predictions of rigid boundary calculations as expected by our model

  15. NbN thin films for superconducting radio frequency cavities

    Science.gov (United States)

    Roach, W. M.; Skuza, J. R.; Beringer, D. B.; Li, Z.; Clavero, C.; Lukaszew, R. A.

    2012-12-01

    NbN thin films have the potential to be incorporated into radio frequency cavities in a multilayer coating to overcome the fundamental field gradient limit of 50 MV m-1 for the bulk niobium based technology that is currently implemented in particle accelerators. In addition to having a larger critical field value than bulk niobium, NbN films develop smoother surfaces which are optimal for cavity performance and lead to fewer losses. Here, we present a study on the correlation of film deposition parameters, surface morphology, microstructure, transport properties and superconducting properties of NbN thin films. We have achieved films with bulk-like lattice parameters and superconducting transition temperatures. These NbN films have a lower surface roughness than similarly grown niobium films of comparable thickness. The potential application of NbN thin films in accelerator cavities is discussed.

  16. NbN thin films for superconducting radio frequency cavities

    International Nuclear Information System (INIS)

    Roach, W M; Clavero, C; Lukaszew, R A; Skuza, J R; Beringer, D B; Li, Z

    2012-01-01

    NbN thin films have the potential to be incorporated into radio frequency cavities in a multilayer coating to overcome the fundamental field gradient limit of 50 MV m −1 for the bulk niobium based technology that is currently implemented in particle accelerators. In addition to having a larger critical field value than bulk niobium, NbN films develop smoother surfaces which are optimal for cavity performance and lead to fewer losses. Here, we present a study on the correlation of film deposition parameters, surface morphology, microstructure, transport properties and superconducting properties of NbN thin films. We have achieved films with bulk-like lattice parameters and superconducting transition temperatures. These NbN films have a lower surface roughness than similarly grown niobium films of comparable thickness. The potential application of NbN thin films in accelerator cavities is discussed. (paper)

  17. Superconducting oxide thin films by ion beam sputtering

    International Nuclear Information System (INIS)

    Kobrin, P.H.; DeNatale, J.F.; Housley, R.M.; Flintoff, J.F.; Harker, A.B.

    1987-01-01

    Superconducting thin films of ternary copper oxides from the Y-Ba-Cu-O and La-Sr-Cu-O systems have been deposited by ion beam sputtering of ceramic targets. Crystallographic orientation of the polycrystalline films has been shown to vary with substrate identity, deposition temperature and annealing temperature. The onset of the superconductive transition occurs near 90K in the Y-Ba-Cu-O system. Fe impurities of < 0.2% have been found to inhibit the superconducting transition, probably by migrating to the grain boundaries

  18. Superconducting properties of clustered PbBi films

    International Nuclear Information System (INIS)

    Lobb, C.J.; Tinkham, M.; Klapwijk, T.M.; Smith, A.D.; Harvard Univ., Cambridge, MA

    1981-01-01

    Superconducting films with high resistance/square have been widely studied as a model of the Kosterlitz-Thouless transition. We show that the behavior of high R clean films near the thickness at which electrical conduction begins is dominated by a few paths across the film and thus should not be interpreted as a Kosterlitz-Thouless transition. Instead, this behavior is consistent with a simple percolation model for the connectivity fluctuations across the film. (orig.)

  19. Investigation of DC current injection effect on the microwave characteristics of HTS YBCO microstrip resonators

    Energy Technology Data Exchange (ETDEWEB)

    Nurgaliev, T., E-mail: timur@ie.bas.bg [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chausse, 1784 Sofia (Bulgaria); Blagoev, B.; Mateev, E.; Neshkov, L. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chausse, 1784 Sofia (Bulgaria); Strbik, V. [Institute of Electrical Engineering, Slovak Academy of Sciences, Dúbravská cesta 9, 841 04 Bratislava (Slovakia); Uspenskaya, L. [Institute of Solid State Physics, Russian Academy of Sciences, 142432 Chernogolovka, Moscow (Russian Federation); Nedkov, I. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chausse, 1784 Sofia (Bulgaria); Chromik, Š. [Institute of Electrical Engineering, Slovak Academy of Sciences, Dúbravská cesta 9, 841 04 Bratislava (Slovakia)

    2014-03-15

    Highlights: • Current (spin) injection effect in LSMO/YBCO was studied by impedance measurements. • Complex impedance of YBCO increases at current injection from LSMO to YBCO at 77 K. • This increase is due to an increase of the quasiparticle conductivity of YBCO. • Injection does not significantly affect the relaxation time of the quasiparticles. - Abstract: The DC current injection effect from a ferromagnetic (FM) La{sub 0.7}Sr{sub 0.3}MnO{sub 3} (LSMO) to a high temperature superconducting (HTS) Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7−x} (YBCO) thin film was investigated by the microwave surface impedance measurements in a FM/HTS structure, formed as a microstrip resonator for improving the sensitivity of the experiments. The quality factor and the resonance frequency of this structure were found to strongly depend on the current strength, injected from the LSMO electrode into the HTS microstrip electrode. The magnetic penetration depth and the quasiparticle conductivity of the HTS component were determined to increase under DC current injection process, which in all probability stimulated breaking of Cooper pairs and led to a decrease of the superfluid concentration and an increase of the normal fluid concentration without significantly affecting the relaxation time of the quasiparticles.

  20. Modeling flux pinning in thin undoped and BazRo3-doped YBCO films

    DEFF Research Database (Denmark)

    Paturi, P.; Irjala, M.; Huhtinen, H.

    2009-01-01

    A simple model based on distributions of twin boundaries, dislocations, and BaZrO3 nanorods is presented to describe the Jc properties of undoped and BaZrO3 (BZO)-doped YBa2Cu3Ox thin films. The model accurately describes the shape of Jc(B,T) curves of the films, when the pinning site distributions...... are taken from distributions of twin spacings and BZO nanorods from transmission electron microscope images. Thus, assuming that the model can be used for prediction of the Jc properties, we conclude that for enhancement of undoped films more crystalline defects are needed and for doped films a dopant...

  1. Synthesis of in-plane aligned a-axis YBa2Cu3O7-δ thin films

    International Nuclear Information System (INIS)

    Young, K.H.; Sun, J.Z.

    1991-01-01

    We report the successful synthesis of superconducting YBa 2 Cu 3 O 7-δ (YBCO) (100) thin films with alignment of the in-plane c axis. These films were grown on single crystal NdGaO 3 (110) substrates. The twofold symmetry of the substrate surface is believed to lead to anisotropic alignment of the in-plane c axis of the epitaxial YBCO (100) film. X-ray diffraction studies indicate that over 80% of the film grew epitaxially with the YBCO [100] perpendicular to the substrate surface, and YBCO [001] aligned along one pseudo-cubic axis of the NdGaO 3 . The superconductivity onset of the film was measured to be 89 K by ac susceptibility

  2. Intrinsic and experimental quasiparticle recombination times in superconducting films

    International Nuclear Information System (INIS)

    Eisenmenger, W.; Lassmann, K.; Trumpp, H.J.; Krauss, R.

    1977-01-01

    Experimental quasiparticle recombination lifetime data for superconducting Al, Sn, and Pb films are compared with calculations based on a ray acoustic model taking account of the film thickness dependence of the reabsorption of recombination phonons. Information on the true or intrinsic quasiparticle recombination lifetime obtained from these and other data is discussed. (orig.) [de

  3. Y-Ba-Cu-O superconducting film on oxidized silicon

    International Nuclear Information System (INIS)

    Gupta, R.P.; Khokle, W.S.; Dubey, R.C.; Singhal, S.; Nagpal, K.C.; Rao, G.S.T.; Jain, J.D.

    1988-01-01

    We report thick superconducting films of Y-Ba-Cu-O on oxidized silicon substrates. The critical temperatures for onset and zero resistance are 96 and 77 K, respectively. X-ray diffraction analysis predicts 1, 2, 3 composition and orthorhombic phase of the film

  4. Vaporization of a mixed precursors in chemical vapor deposition for YBCO films

    Science.gov (United States)

    Zhou, Gang; Meng, Guangyao; Schneider, Roger L.; Sarma, Bimal K.; Levy, Moises

    1995-01-01

    Single phase YBa2Cu3O7-delta thin films with T(c) values around 90 K are readily obtained by using a single source chemical vapor deposition technique with a normal precursor mass transport. The quality of the films is controlled by adjusting the carrier gas flow rate and the precursor feed rate.

  5. Realization of superconductive films by screen printing

    International Nuclear Information System (INIS)

    Baudry, H.

    1988-01-01

    Screen printing is a promising method to manufacture superconductive lines making use of superconductive ceramics. An ink has been realized with YBa 2 Cu 3 0 7-x' and the process conditions defined by thermal analysis. A superconductive transition is observed after screen printing on MgO. The firing of the layer is made at 920 0 C followed by a reoxidation step at 420 0 C. The silver electrical contacts are also screen printed [fr

  6. Superconductivity applications for infrared and microwave devices; Proceedings of the Meeting, Orlando, FL, Apr. 19, 20, 1990

    Science.gov (United States)

    Bhasin, Kul B.; Heinen, Vernon O.

    1990-10-01

    Various papers on superconductivity applications for IR and microwave devices are presented. The individual topics addressed include: pulsed laser deposition of Tl-Ca-Ba-Cu-O films, patterning of high-Tc superconducting thin films on Si substrates, IR spectra and the energy gap in thin film YBa2Cu3O(7-delta), high-temperature superconducting thin film microwave circuits, novel filter implementation utilizing HTS materials, high-temperature superconductor antenna investigations, high-Tc superconducting IR detectors, high-Tc superconducting IR detectors from Y-Ba-Cu-O thin films, Y-Ba-Cu0-O thin films as high-speed IR detectors, fabrication of a high-Tc superconducting bolometer, transition-edge microbolometer, photoresponse of YBa2Cu3O(7-delta) granular and epitaxial superconducting thin films, fast IR response of YBCO thin films, kinetic inductance effects in high-Tc microstrip circuits at microwave frequencies.

  7. Magnetic Field Enhanced Superconductivity in Epitaxial Thin Film WTe2.

    Science.gov (United States)

    Asaba, Tomoya; Wang, Yongjie; Li, Gang; Xiang, Ziji; Tinsman, Colin; Chen, Lu; Zhou, Shangnan; Zhao, Songrui; Laleyan, David; Li, Yi; Mi, Zetian; Li, Lu

    2018-04-25

    In conventional superconductors an external magnetic field generally suppresses superconductivity. This results from a simple thermodynamic competition of the superconducting and magnetic free energies. In this study, we report the unconventional features in the superconducting epitaxial thin film tungsten telluride (WTe 2 ). Measuring the electrical transport properties of Molecular Beam Epitaxy (MBE) grown WTe 2 thin films with a high precision rotation stage, we map the upper critical field H c2 at different temperatures T. We observe the superconducting transition temperature T c is enhanced by in-plane magnetic fields. The upper critical field H c2 is observed to establish an unconventional non-monotonic dependence on temperature. We suggest that this unconventional feature is due to the lifting of inversion symmetry, which leads to the enhancement of H c2 in Ising superconductors.

  8. Pulsed laser deposition and characterisation of thin superconducting films

    Energy Technology Data Exchange (ETDEWEB)

    Morone, A [CNR, zona industriale di Tito Scalo, Potenza (Italy). Istituto per i Materiali Speciali

    1996-09-01

    Same concepts on pulsed laser deposition of thin films will be discussed and same examples of high transition temperature (HTc) BiSrCaCuO (BISCO) and low transition temperature NbN/MgO/NbN multilayers will be presented. X-ray and others characterizations of these films will be reported and discussed. Electrical properties of superconducting thin films will be realized as a function of structural and morphological aspect.

  9. Micropatterned superconducting film circuitry for operation in hybrid quantum devices

    International Nuclear Information System (INIS)

    Bothner, Daniel

    2013-01-01

    This thesis discusses three aspects of the arduous way towards hybrid quantum systems consisting of superconducting circuits and ensembles of ultracold paramagnetic atoms. In the first part of the thesis, superconducting coplanar microwave resonators as used for quantum information processing with superconducting qubits are investigated in magnetic fields. In the second part of the thesis integrated atom chips are designed and fabricated, which offer the possibility to trap an ensemble of ultracold atoms close to a superconducting coplanar resonator on that chip. In the third and last part of the thesis, unconventional disordered and quasiperiodic arrangements of microfabricated holes (antidots) in superconducting films are patterned and investigated with respect to the impact of the arrangement on the superconductor transport properties in magnetic fields.

  10. Preparation of YBa2Cu3O7-x superconducting solutions and films from alkoxide-based precursors using sol-gel method and investigation of their chemical reaction mechanisms

    International Nuclear Information System (INIS)

    Mutlu, Ibrahim Halil; Acun, Hediye; Celik, Erdal; Turkmen, Hasan

    2007-01-01

    In the development of coated superconductors sol-gel technique has been widely used as an effective processing method, especially in making long-length wires and tapes. However, one drawback associated with the deposition of YBa 2 Cu 3 O 7-x and Gd 2 O 3 buffer layer on Ni tape is the adhesion characteristic at interfaces YBCO-Gd 2 O 3 and Gd 2 O 3 -NiO and NiO-Ni substrate. In this paper, two strategies for adhesion enhancement of multilayered ceramic oxide coatings on Ni substrate were proposed: (1) formation of chemical bonds through surface condensation reactions, and development of ceramic networks through diffusion of alkoxide precursors. The current research has focused on the fabrication and adhesion of YBCO coatings on buffered Ni substrate using nine solutions prepared from Y, Ba and Cu alkoxides, solvent and chelating agent. Only two of YBCO solutions were successfully obtained while the rest of them were unsuccessful. Among these solutions we scrutinized chemical reaction mechanisms of a successful and an unsuccessful solution for comparison. How the chemical bonds and solubility were affected by the acids, base and solvents used in the solutions was demonstrated. It was shown that pH of the solution, homogeneity of the solution and gelation, steric affect of the chemicals in sol-gel solutions are significant issues to obtain high quality superconducting YBCO thin films. In addition, X-ray diffraction (XRD) was used to analyze phase structure of YBCO and compare results of chemical reactions obtained by a chemdraw programme. Scanning electron microscope (SEM) studies was carried out to examine microstructures of YBCO films produced from alkoxide precursors, solvent, chelating agent and modifying liquid chemical materials such as triethanolamine or ammonium hydroxide. It was found to be YBCO, Gd 2 O 3 , NiO and Ni phases in YBCO/Gd 2 O 3 /Ni sample from XRD analysis. That the solution prepared by using triethanolamine provided the best film quality and

  11. Factors that determine the presence of particles in YBCO films grown by PLD

    International Nuclear Information System (INIS)

    Barrales-Guadarrama, V R; Rodríguez-Rodríguez, E M; Barrales-Guadarrama, R; Reyes Ayala, N

    2017-01-01

    The method of growing thin films PLD, is widely used in applications and possesses great potential in thin YBa 2 Cu 3 O 7-δ films production with outstanding physical properties. However, it is limited in nano and micro technology due to the presence of particles on the surface of the films. This article describes some causes that create these particles. YBa 2 Cu 3 O 7-δ films have been grown on electrolytic copper used as a variable model the distance target-substrate. The effects are studied through Scanning Electronic Microscopy. It is observed particles with a large variety of shapes and distributions. The results show that ranging the target-substrate distance, the superficial morphology is modified. An evidence of it, is that the evaporation of d B-S = 7 cm, is more coherent that d B-S = 3 cm. Therefore, exist a relation between the morphology and the parameters of growing. Also affect, the structural change that exists among the substrate and the film formation, the substrate preparation and it must not be monocrystalline, these factors define a kinetic and a mechanism of growing that promotes a heterogeneous nucleation. (paper)

  12. New Fast Response Thin Film-Based Superconducting Quench Detectors

    CERN Document Server

    Dudarev, A; van de Camp, W; Ravaioli, E; Teixeira, A; ten Kate, H H J

    2014-01-01

    Quench detection on superconducting bus bars and other devices with a low normal zone propagation velocity and low voltage build-up is quite difficult with conventional quench detection techniques. Currently, on ATLAS superconducting bus bar sections, superconducting quench detectors (SQD) are mounted to detect quench events. A first version of the SQD essentially consists of an insulated superconducting wire glued to a superconducting bus line or windings, which in the case of a quench rapidly builds up a relatively high resistance that can be easily and quietly detected. We now introduce a new generation of drastically improved SQDs. The new version makes the detection of quenches simpler, more reliable, and much faster. Instead of a superconducting wire, now a superconducting thin film is used. The layout of the sensor shows a meander like pattern that is etched out of a copper coated 25 mu m thick film of Nb-Ti glued in between layers of Kapton. Since the sensor is now much smaller and thinner, it is easi...

  13. Superconducting properties and microstructure of YBa2Cu3O7-δ/PrBa2Cu3O7-δ superlattices

    International Nuclear Information System (INIS)

    Lowndes, D.H.; Norton, D.P.; Zheng, X.Y.; Zhu, Shen

    1991-10-01

    Epitaxial YBa 2 Cu 3 O 7-δ /PrBa 2 Cu 3 O 7-δ (YBCO/PBCO) superlattices are tools for systematic, fundamental studies of high-temperature superconductivity. The variation of T c in YBCO/PBCO superlattices can be understood as arising from changes in the interlayer phase coupling between YBCO layers that are highly two-dimensional when they are very thin (∼1--2 c-axis unit cells) and completely isolated from each other. Single-cell-thick YBCO layers, containing isolated pairs of CuO 2 planes, are found to be superconducting at T c ∼ 20 K, in a PBCO matrix. The resistance in the superconducting transition region scales with temperature as expected for the (flux flow) resistance produced by thermally generated 2D vortices, or for a 2D array of superconducting weak links. Relative to both thin-film and single-crystal HTSc specimens, the thin superconducting layers in YBCO/PBCO superlattices exhibit a greatly expanded temperature range over which characteristic 2D dissipation can be observed, as a consequence of the enhanced anisotropy and reduced dimensionality of the YBCO layers. Scanning tunneling microscope studies reveal that YBCO films and YBCO/PBCO superlattices grow unit cell-by-unit cell by a terraced-island growth mechanism. On miscut, near-(001) substrates the terraces are epitaxially aligned with the substrate crystal lattice and spiral growth structures (screw dislocation-mediated growth) are not seen. These observations explain the steps or ''kinks'' that are seen in cross-section Z-contrast TEM images of YBCO/PBCO superlattices. The kinks may correspond physically to regions where the supercurrent must tunnel along the c- axis, and thus may be weak-link barriers. 31 refs., 7 figs

  14. Quenching of superconductivity in disordered thin films by phase fluctuations

    International Nuclear Information System (INIS)

    Hebard, A.F.; Palaanen, M.A.

    1992-01-01

    The amplitude Ψ 0 and phase Φ of the superconducting order parameter in thin-film systems are affected differently by disorder and dimensionality. With increasing disorder superconducting long range order is quenched in sufficiently thin films by physical processes driven by phase fluctuations. This occurs at both the zero-field vortex-antivortex unbinding transition and at the zero-temperature magnetic-field-tuned superconducting-insulating transition. At both of these transitions Ψ 0 is finite and constant, vanishing only when temperature, disorder, and/or magnetic field are increased further. Experimental results on amorphous-composite InO x films are presented to illustrate these points and appropriate comparisons are made to other experimental systems. (orig.)

  15. Microwave absorption in YBCO/PrBCO superlattices

    International Nuclear Information System (INIS)

    Carlos, W.E.; Kaplan, R.; Lowndes, D.H.; Norton, D.P.

    1992-01-01

    In this paper, non-resonant microwave absorption is employed to probe YBCO/PrBCO superlattices and compare the response to that of a YBCO film. Near the transition temperatures, the response of the superlattice samples and the YBCO film have similar amplitudes and orientation dependencies. At lower temperatures, the response of the superlattices is much stronger than that of the YBCO film and, while both responses are hysteretic at low temperatures, the widths of the hysteresis have opposite orientation dependencies, which the authors attribute to the role of the PrBCO layers

  16. Raman scattering studies of YBa2Cu3O7-x thin films grown by chemical vapor deposition and metal-organic deposition

    International Nuclear Information System (INIS)

    Lee, E.; Yoon, S.; Um, Y.M.; Jo, W.; Seo, C.W.; Cheong, H.; Kim, B.J.; Lee, H.G.; Hong, G.W.

    2007-01-01

    We present results of Raman scattering studies of superconducting YBa 2 Cu 3 O 7-x (YBCO) films grown by chemical vapor deposition and metal-organic deposition methods. It is shown by X-ray diffraction that all the as-grown YBCO films have a highly c-axis oriented and in-plane aligned texture. Raman scattering measurements were used to investigate optical phonon modes, oxygen contents, structural properties, and second-phases of the YBCO coated conductors. Raman spectra of YBCO films with lower-transport qualities exhibit additional phonon modes at ∼300 cm -1 , ∼600 cm -1 , and ∼630 cm -1 , which are related to second-phases such as Ba 2 Cu 3 O 5.9 and BaCuO 2 . Our results strongly suggest that Raman scattering be useful for optimizing YBCO film growth conditions

  17. Nonlinear surface impedance of YBCO thin films: Measurements, modeling, and effects in devices

    International Nuclear Information System (INIS)

    Oates, D.E.; Koren, G.; Polturak, E.

    1995-01-01

    High-T c thin films continue to be of interest for passive device applications at microwave frequencies, but nonlinear effects may limit the performance. To understand these effects we have measured the nonlinear effects may limit the performance. To understand these effects we have measured the nonlinear surface impedance Z s in a number of YBa 2 Cu 3 O 7-x thin films as a function of frequency from 1 to 18 GHz, rf surface magnetic field H rf to 1500 Oe, and temperature from 4 K to T c . The results at low H rf are shown to agree quantitatively with a modified coupled-grain model and at high H rf with hysteresis-loss calculations using the Bean critical-state model applied to a thin strip. The loss mechanisms are extrinsic properties resulting from defects in the films. We also report preliminary measurements of the nonlinear impedance of Josephson junctions, and the results are related to the models of nonlinear Z s . The implications of nonlinear Z s for devices are discussed using the example of a five-pole bandpass filter

  18. High-spatial resolution resistivity mapping of large-area YBCO films by a near-field millimeter-wave microscope

    International Nuclear Information System (INIS)

    Golosovsky, M.; Galkin, A.; Davidov, D.

    1996-01-01

    The authors demonstrate a new millimeter-wave technique for the resistivity mapping of large-area conducting films, namely, a near-field resistivity microscope. The microscope is based on the idea that electromagnetic waves are transmitted through a narrow resonant slit with high efficiency. By scanning this slit at fixed height above an inhomogeneous conducting surface and measuring the intensity and phase of the reflected wave, the resistivity of this surface may be determined with a 10--100 microm spatial resolution using 80-GHz radiation. Using this technique, they map normal-sate resistivity of 1 in x 1 in YBCO films at ambient temperature. In some films they find inhomogeneities of the normal-state sheet resistance of the order of 10%--20%

  19. Microwave Josephson generation in thin film superconducting bridges

    International Nuclear Information System (INIS)

    Gubankov, V.N.; Koshelets, V.P.; Ovsyannikov, G.A.

    1975-01-01

    Thin-film bridges have some advantage over other types of superconducting weak links: good definition of electromagnetic parameters and of weak region geometry. Up to now Josephson properties of bridges have been investigated by using indirect methods (the effect of magnetic field on the critical current I 0 , the bridge behavior in a microwave field, etc.). Direct experimental observation of Josephson radiation from autonomous thin film bridges is reported. Microwave radiation in tin bridges of 'variable' thickness has been investigated where the thickness of the film forming the bridge is far less than the thickness of the bank films. (Auth.)

  20. LaNiO3 buffer layers for high critical current density YBa2Cu3O7-δ and Tl2Ba2CaCu2O8-δ films

    International Nuclear Information System (INIS)

    Carlson, C.M.; Parilla, P.A.; Siegal, M.P.; Ginley, D.S.; Wang, Y.; Blaugher, R.D.; Price, J.C.; Overmyer, D.L.; Venturini, E.L.

    1999-01-01

    We demonstrate high critical current density superconducting films of YBa 2 Cu 3 O 7-δ (YBCO) and Tl 2 Ba 2 CaCu 2 O 8-δ (Tl-2212) using LaNiO 3 (LNO) buffer layers. YBCO films grown on an LNO buffer layer have only a slightly lower J c (5 K, H=0) than films grown directly on a bare LaAlO 3 substrate. YBCO films grown on LNO buffer layers exhibit minor microstructural disorder and enhanced flux pinning. LNO-buffered Tl-2212 samples show large reductions in J c at all temperatures and fields compared to those grown on bare LaAlO 3 , correlating to both a-axis grain and nonsuperconducting phase formation. LNO could be a promising buffer layer for both YBCO and Tl-based superconducting films in coated conductor applications. copyright 1999 American Institute of Physics

  1. LaNiO3 Buffer Layers for High Critical Current Density YBa2Cu3O7δ and Tl2Ba2CaCu2O8δ Films

    International Nuclear Information System (INIS)

    Carlson, C.M.; Parilla, P.A.; Siegal, M.P.; Ginley, D.S.; Wang, Y.-T.; Blaugher, R.D.; Price, J.C.; Overmyer, D.L.; Venturini, E.L.

    1999-01-01

    We demonstrate high critical current density superconducting films of YBa 2 Cu 3 O 7-δ (YBCO) and Tl 2 Ba 2 CaCu 2 O 8-δ (Tl-2212) using LaNiO 3 (LNO) buffer layers. YBCO films grown on an LNO buffer layer have only a slightly lower J c (5K, H=0) than films grown directly on a bare LaAlO 3 substrate. It is noteworthy that YBCO films grown on LNO buffer layers exhibit minor microstructural disorder and enhanced flux pinning. LNO-buffered Tl-2212 samples show large reductions in J c at all temperatures and fields compared to those grown on bare LaAlO 3 , correlating to both a-axis grain and nonsuperconducting phase formation. With additional optimization, LNO could be a promising buffer layer for both YBCO and Tl-based superconducting films, perhaps ideally suited for coated conductor applications

  2. Nb3Ge superconductive films grown with nitrogen

    International Nuclear Information System (INIS)

    Sigsbee, R.A.

    1978-01-01

    A superconductive film of Nb 3 Ge is produced by providing within a vacuum chamber a heated substrate and sources of niobium and germanium, reducing the pressure within the chamber to a residual pressure no greater than about 10 -5 mm Hg, introducing nitrogen into the resulting evacuated chamber in controlled amounts and vaporizing the niobium and germanium to deposit a film of Nb 3 Ge on the heated substrate

  3. Tunneling probe of fluctuating superconductivity in disordered thin films

    Science.gov (United States)

    Dentelski, David; Frydman, Aviad; Shimshoni, Efrat; Dalla Torre, Emanuele G.

    2018-03-01

    Disordered thin films close to the superconductor-insulator phase transition (SIT) hold the key to understanding quantum phase transition in strongly correlated materials. The SIT is governed by superconducting quantum fluctuations, which can be revealed, for example, by tunneling measurements. These experiments detect a spectral gap, accompanied by suppressed coherence peaks, on both sides of the transition. Here we describe the insulating side in terms of a fluctuating superconducting field with finite-range correlations. We perform a controlled diagrammatic resummation and derive analytic expressions for the tunneling differential conductance. We find that short-range superconducting fluctuations suppress the coherence peaks even in the presence of long-range correlations. Our approach offers a quantitative description of existing measurements on disordered thin films and accounts for tunneling spectra with suppressed coherence peaks.

  4. Spatial characterization of the edge barrier in wide superconducting films

    Science.gov (United States)

    Sivakov, A. G.; Turutanov, O. G.; Kolinko, A. E.; Pokhila, A. S.

    2018-03-01

    The current-induced destruction of superconductivity is discussed in wide superconducting thin films, whose width is greater than the magnetic field penetration depth, in weak magnetic fields. Particular attention is paid to the role of the boundary potential barrier (the Bin-Livingston barrier) in critical state formation and detection of the edge responsible for this critical state with different mutual orientations of external perpendicular magnetic field and transport current. Critical and resistive states of the film were visualized using the space-resolving low-temperature laser scanning microscopy (LTLSM) method, which enables detection of critical current-determining areas on the film edges. Based on these observations, a simple technique was developed for investigation of the critical state separately at each film edge, and for the estimation of residual magnetic fields in cryostats. The proposed method only requires recording of the current-voltage characteristics of the film in a weak magnetic field, thus circumventing the need for complex LTLSM techniques. Information thus obtained is particularly important for interpretation of studies of superconducting film single-photon light emission detectors.

  5. Reduced thermal budget processing of Y--Ba--Cu--O high temperature superconducting thin films by metalorganic chemical vapor deposition

    International Nuclear Information System (INIS)

    Singh, R.; Sinha, S.; Hsu, N.J.; Ng, J.T.C.; Chou, P.; Thakur, R.P.S.; Narayan, J.

    1991-01-01

    Metalorganic chemical vapor deposition (MOCVD) has the potential of emerging as a viable technique to fabricate ribbons, tapes, coated wires, and the deposition of films of high temperature superconductors, and related materials. As a reduced thermal budget processing technique, rapid isothermal processing (RIP) based on incoherent radiation as the source of energy can be usefully coupled to conventional MOCVD. In this paper we report on the deposition and characterization of high quality superconducting thin films of Y--Ba--Cu--O (YBCO) on MgO and SrTiO 3 substrates by RIP assisted MOCVD. By using a mixture of N 2 O and O 2 as the oxygen source films deposited initially at 600 degree C for 1 min and then at 740 degree C for 30 min are primarily c-axis oriented and with zero resistance being observed at 84 and 89 K for MgO and SrTiO 3 substrates, respectively. The zero magnetic field current densities at 77 K for MgO and SrTiO 3 substrates are 1.2x10 6 and 1.5x10 6 A/cm 2 , respectively. It is envisaged that high energy photons from the incoherent light source and the use of a mixture of N 2 O and O 2 as the oxygen source, assist chemical reactions and lower overall thermal budget for processing of these films

  6. Anisotrophic currents and flux jumps in high-T{sub c} superconducting films with self-organized arrays of planar defects

    Energy Technology Data Exchange (ETDEWEB)

    Yurchenko, V.V., E-mail: vitaliy.yurchenko@fys.uio.n [Department of Physics, University of Oslo, P.B. 1048, Blindern, 0316 Oslo (Norway); Qviller, A.J. [Department of Physics, University of Oslo, P.B. 1048, Blindern, 0316 Oslo (Norway); Mozhaev, P.B.; Mozhaeva, J.E. [Department of Physics, Technical University of Denmark, Kgs. Lyngby DK-2800 (Denmark); Institute of Physics and Technology RAS, Moscow 117218 (Russian Federation); Hansen, J.B.; Jacobsen, C.S. [Department of Physics, Technical University of Denmark, Kgs. Lyngby DK-2800 (Denmark); Kotelyanskii, I.M. [Institute of Radio Engineering and Electronics RAS, Fryazino, 141190 Moscow District (Russian Federation); Pan, A.V. [Institute for Superconducting and Electronic Materials, University of Wollongong, Northfields Avenue, Wollongong 2522 (Australia); Johansen, T.H. [Department of Physics, University of Oslo, P.B. 1048, Blindern, 0316 Oslo (Norway)

    2010-10-01

    Regular arrays of planar defects with a period of a few nanometers can be introduced in superconducting YBa{sub 2}Cu{sub 3}O{sub 7-{delta}}(YBCO) thin films by depositing them on vicinal (also called miscut or tilted) substrates. This results in the anisotropy of critical currents flowing in the plane of the film. We present results of real-time magneto-optical imaging (MOI) of magnetic flux distribution and dynamics in a series of YBCO thin films deposited on NdGaO{sub 3} substrates with different miscut angles {theta}. MOI allows reconstructing the current flow profiles. From the angle formed between domains with different directions of the current flow we determine the anisotropy parameter of the in-plane current, as well as its field and temperature dependences. The artificially introduced defects also have a dramatic effect on the dynamics of the flux propagation: for 10{sup o}<{theta}<14{sup o} the magnetic flux propagates along the easy channels intermittently, i.e. in a form of flux jumps. This behavior is indicative of thermo-magnetic instability in superconductors, but we argue that this effect can be of a different nature.

  7. Measurements and analysis of the noise spectral density of YBCO films

    International Nuclear Information System (INIS)

    Taoufik, A.; Bghour, M.; Labrag, A.; Bouaaddi, A.; Abaragh, A.; Ramzi, A.; Senoussi, S.; Tirbiyine, A.

    2006-01-01

    We studied the voltage noise spectral density S V (f,T,H) dependence on frequency f, temperature T and applied magnetic field H in YBa 2 Cu 3 O 7-δ films. The voltage noise spectral density S V (f) as a function of frequency exhibits 1/f behavior according to a Lorentzian shape A [(1+πf/f 0 ) B ] C , where A, f 0 , B, C constants which are determined and compared for many values of H. The influence of temperature and magnetic field is clearly observed as a function of temperature, S V (T) is found to vanish at T g , the temperature of vortex glass transition, according to a (T-T g ) x law. We interpreted those results by the formation of a large distribution of glass vortex domains. Approaching T g , these domains grow in size and lifetime, while at T g those parameters diverge. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  8. AFM plough YBCO micro bridges: substrate effects

    CSIR Research Space (South Africa)

    Elkaseh, A

    2009-04-01

    Full Text Available AFM nanolithography was used as a novel cutting technique to define micro-size YBCO superconducting constrictions. Researchers studied the substrate effects on MgO and STO substrates and showed that the observed Shapiro steps from the bridges on STO...

  9. Size and dimensionality effects in superconducting Mo thin films

    International Nuclear Information System (INIS)

    Fabrega, L; Gil, O; Camon, A; Parra-BorderIas, M; Fernandez-MartInez, I; Costa-Kraemer, J L; Briones, F; Sese, J; Gonzalez-Arrabal, R

    2011-01-01

    Molybdenum is a low T c , type I superconductor whose fundamental properties are poorly known. Its importance as an essential constituent of new high performance radiation detectors, the so-called transition edge sensors (TESs) calls for better characterization of this superconductor, especially in thin film form. Here we report on a study of the basic superconducting features of Mo thin films as a function of their thickness. The resistivity is found to rise and the critical temperature decreases on decreasing film thickness, as expected. More relevant, the critical fields along and perpendicular to the film plane are markedly different, thickness dependent and much larger than the thermodynamic critical field of Mo bulk. These results are consistent with a picture of type II 2D superconducting films, and allow estimates of the fundamental superconducting lengths of Mo. The role of morphology in determining the 2D and type II character of the otherwise type I molybdenum is discussed. The possible consequences of this behaviour on the performance of radiation detectors are also addressed.

  10. Pulsed laser deposition of high Tc superconducting thin films

    International Nuclear Information System (INIS)

    Singh, R.K.; Narayan, J.

    1990-01-01

    This paper reports on the pulsed laser evaporation (PLE) technique for deposition of thin films characterized by a number of unique properties. Based on the experimental characteristics, a theoretical model is developed which considers the formation and anisotropic three dimensional expansion of the laser generated plasma. This model explains most of the experimental features observed in PLE. We have also employed the PLE technique for in-situ fabrication of YBa 2 Cu 3 O 7 superconducting thin films on different substrates in the temperature range of 500--650 degrees C. At temperatures below 600 degrees C, a biased interposing ring between the substrate and the target was found to significantly improve the superconducting properties. The minimum ion channeling yields were between 3--3.5% for films deposited on (100) SrTiO 3 and (100) LaAlO 3 substrates

  11. A Method for Suppressing Superconductivity of Thin Films

    Science.gov (United States)

    Suppula, Tarmo; Pekola, Jukka; Kauppinen, Juha

    2003-03-01

    We have developed a method for suppressing superconductivity of thin films. Thin stripes of cobalt grown by e-gun evaporation and patterned by e-beam lithography were placed in the vicinity of aluminium thin film structures. The cobalt stripes were magnetized at 4.2 K with a superconducting coil and the remanence suppressed superconductivity of the Al stripe at temperatures down to 50 mK at least. The magnetization remained in thermal cycling and in a longer storage at room temperature. Motivation for this work is the Coulomb Blockade Thermometer(CBT)^1 which has to be in a normal state to operate. The CBT sensor contains aluminium which is superconducting at temperatures below 1.4 K. An external magnetic field is not always available or acceptable in cryostats. A small grain of permanent magnet mounted to the sensor is another solution, but suspicious if the sensor is put in strong magnetic fields or if "zero field" environment is required. We have shown that suitably patterned and magnetized Co stripes in the vicinity of tunnel junctions of the CBT can solve this problem. The amount of magnetic material in the sensor, as well as the stray field, is very small. This technique may be useful in other low temperature thin film devices also. 1) Product of Nanoway Ltd.

  12. THz spectroscopy on superconducting NbN thin films

    Energy Technology Data Exchange (ETDEWEB)

    Daschke, Lena; Pracht, Uwe S.; Dressel, Martin; Scheffler, Marc [1. Physikalisches Institut, Universitaet Stuttgart (Germany); Ilin, Konstantin S.; Siegel, Michael [Institut fuer Mikro- und Nanoelektronische Systeme, Karlsruher Institut fuer Technologie (Germany)

    2015-07-01

    Epitaxial thin-film niobium nitride (NbN) is a conventional BCS superconductor. In presence of strong disorder, however, electronic inhomogeneities appear, which is not fully understood yet. To obtain a better insight into the physics of such disordered materials, studies on model systems such as structurally tailored films might be useful. Furthermore, disordered NbN films are used for single-photon detection devices, whose proper performance depends on a profound understanding of the superconducting properties. The studied NbN films have a T{sub c} ranging from 10 to 15 K and the superconducting energy gap is easily accessible with THz spectroscopy (0.4 - 5.6 meV). We investigate thin films of NbN sputtered on a sapphire substrate. With a Mach-Zehnder interferometer we measure the amplitude and phase shift of radiation transmitted through the thin-film sample. From there we can determine the real and imaginary parts of the optical conductivity. These results give information about the energy gap, Cooper pair density, and quasiparticle dynamics, including the temperature evolution of these quantities. We found that a film with 10 nm thickness roughly follows the BCS behavior, as expected. We will present results of our measurements on several different NbN samples.

  13. Superconducting parameters of polycrystalline niobium films

    International Nuclear Information System (INIS)

    Kandyba, P.E.; Kolesnikov, D.P.; Tkachev, V.A.

    1978-01-01

    The niobium semi-crystalline films, having a thickness of 200-5,050 A have been studied. The films have been produced by the electron-beam evaporation in the oilless vacuum and by the ionic plasma spraying with diode and triode methods. Determined have been the coherence length, the magnetic field penetration depth and the Ginsburg-andau parameter. An attempt is made to determine the electron states density of the Fermi surface

  14. Vortex variable range hopping in a conventional superconducting film

    Science.gov (United States)

    Percher, Ilana M.; Volotsenko, Irina; Frydman, Aviad; Shklovskii, Boris I.; Goldman, Allen M.

    2017-12-01

    The behavior of a disordered amorphous thin film of superconducting indium oxide has been studied as a function of temperature and magnetic field applied perpendicular to its plane. A superconductor-insulator transition has been observed, though the isotherms do not cross at a single point. The curves of resistance versus temperature on the putative superconducting side of this transition, where the resistance decreases with decreasing temperature, obey two-dimensional Mott variable-range hopping of vortices over wide ranges of temperature and resistance. To estimate the parameters of hopping, the film is modeled as a granular system and the hopping of vortices is treated in a manner analogous to hopping of charges. The reason the long-range interaction between vortices over the range of magnetic fields investigated does not lead to a stronger variation of resistance with temperature than that of two-dimensional Mott variable-range hopping remains unresolved.

  15. Two-dimensional superconductivity in ultrathin disordered thin films

    International Nuclear Information System (INIS)

    Beasley, M.R.

    1992-01-01

    The status of the understanding of two-dimensional superconductivity in ultrathin, disordered thin films is reviewed. The different consequences of microscopic versus macroscopic disorder are stressed. It is shown that microscopic disorder leads to a rapid suppression of the mean-field transition temperature. The consequences of macroscopic disorder are not well understood, but a universal behavior of the zero-bias resistance as a function of field and temperature has been observed. (orig.)

  16. Vortex imaging in superconducting films by scanning Hall probe microscopy

    International Nuclear Information System (INIS)

    Oral, A.; Bending, S.J.; Humphreys, R.G.

    1996-01-01

    The authors have used a low noise Scanning Hall Probe Microscope (SHPM) to study vortex structures in superconducting films. The microscope has high magnetic field (∼2.9 x 10 -8 T/√Hz at 77K) and spatial resolution, ∼0.85 μm. Magnetic field profiles of single vortices in High T c YBa 2 Cu 3 O 7-δ thin films have been successfully measured and the microscopic penetration depth of the superconductor has been extracted as a function of temperature. Flux penetration into the superconductor has been imaged in real time (∼8s/frame)

  17. RF Characterization of Niobium Films for Superconducting Cavities

    CERN Document Server

    Aull† , S; Doebert, S; Junginger, T; Ehiasarian, AP; Knobloch, J; Terenziani, G

    2013-01-01

    The surface resistance RS of superconductors shows a complex dependence on the external parameters such as temperature, frequency or radio-frequency (RF) field. The Quadrupole Resonator modes of 400, 800 and 1200 MHz allow measurements at actual operating frequencies of superconducting cavities. Niobium films on copper substrates have several advantages over bulk niobium cavities. HIPIMS (High-power impulse magnetron sputtering) is a promising technique to increase the quality and therefore the performance of niobium films. This contribution will introduce CERNs recently developed HIPIMS coating apparatus. Moreover, first results of niobium coated copper samples will be presented, revealing the dominant loss mechanisms.

  18. Fractional flux excitations and flux creep in a superconducting film

    International Nuclear Information System (INIS)

    Lyuksyutov, I.F.

    1995-01-01

    We consider the transport properties of a modulated superconducting film in a magnetic field parallel to the film. Modulation can be either intrinsic, due to the layered structure of the high-T c superconductors, or artificial, e.g. due to thickness modulation. This system has an infinite set ( >) of pinned phases. In the pinned phase the excitation of flux loops with a fractional number of flux quanta by the applied current j results in flux creep with a generated voltage V ∝ exp[-jo/j[. (orig.)

  19. Novel method for fabrication of integrated resistors on bilayer Ag/YBa2Cu3O7 films using Ni implantation

    International Nuclear Information System (INIS)

    LaGraff, J.R.; Chan, H.; Murduck, J.M.; Hong, S.H.; Ma, Q.Y.

    1997-01-01

    A novel ion implantation method is described for fabricating low inductance integrated resistors on Ag/YBa 2 Cu 3 O 7 (YBCO) bilayer thin films. Parallel high and low value resistors were simultaneously formed by patterning bilayer films into 10-μm-wide lines, then masking and implanting with Ni to selectively inhibit superconductivity in YBCO. Low value resistors (<1Ω/sq) were formed at 77 K as the supercurrent bypassed the Ni-doped nonsuperconducting YBCO and was shunted through the overlying low resistivity Ag metal. High value resistors (20 - 140 Ω/sq) were formed by removing Ag from above the implanted YBCO forcing the current through the implanted YBCO region. The sheet resistance of both types of resistors was found to increase systematically with increasing Ni implant energy. copyright 1997 American Institute of Physics

  20. Prospects for enhancement of critical current of HTSC: thin films with artificial pinning centres

    Energy Technology Data Exchange (ETDEWEB)

    Mozhaev, P.B. (Institute of Physics and Technology RAS, Moscow (Russian Federation)); Mozhaev, J.E.; Khoryushin, A.V.; Bindslev Hansen, J.; Jacobsen, C.S. (Technical Univ. of Denmark, Dept. of Physics, Kgs. Lyngby (Denmark)); Kotelyanskil, I.M.; Luzanov, V.A. (Institute of Radio Engineering and Electronics RAS, Moscow (Russian Federation)); Puriy, A.V. (Moscow Institute of Physics and Technology, Moscow (Russian Federation)); Yurchenko, V.; Johansen, T. (Univ. of Oslo, Dept. of Physics, Oslo (Norway))

    2008-10-15

    Improvement of the critical current of YBCO thin films and heterostructures remains one of the main tasks for fabrication of modern superconducting wires and connectors. Possible ways of achieving the goal are choice of superconductor composition, engineering of artificial pinning centres, and combination of the superconducting layer with other materials. The team of the Department of Physics at Technical University of Denmark is working in all these fields and this paper is a short review of our achievements in an attempt to improve the critical current density of YBCO thin films. (au)

  1. Local imaging of magnetic flux in superconducting thin films

    Energy Technology Data Exchange (ETDEWEB)

    Shapoval, Tetyana

    2010-01-26

    Local studies of magnetic flux line (vortex) distribution in superconducting thin films and their pinning by natural and artificial defects have been performed using low-temperature magnetic force microscopy (LT-MFM). Taken a 100 nm thin NbN film as an example, the depinning of vortices from natural defects under the influence of the force that the MFM tip exerts on the individual vortex was visualized and the local pinning force was estimated. The good agreement of these results with global transport measurements demonstrates that MFM is a powerful and reliable method to probe the local variation of the pinning landscape. Furthermore, it was demonstrated that the presence of an ordered array of 1-{mu}m-sized ferromagnetic permalloy dots being in a magneticvortex state underneath the Nb film significantly influences the natural pinning landscape of the superconductor leading to commensurate pinning effects. This strong pinning exceeds the repulsive interaction between the superconducting vortices and allows vortex clusters to be located at each dot. Additionally, for industrially applicable YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} thin films the main question discussed was the possibility of a direct correlation between vortices and artificial defects as well as vortex imaging on rough as-prepared thin films. Since the surface roughness (droplets, precipitates) causes a severe problem to the scanning MFM tip, a nanoscale wedge polishing technique that allows to overcome this problem was developed. Mounting the sample under a defined small angle results in a smooth surface and a monotonic thickness reduction of the film along the length of the sample. It provides a continuous insight from the film surface down to the substrate with surface sensitive scanning techniques. (orig.)

  2. Local imaging of magnetic flux in superconducting thin films

    International Nuclear Information System (INIS)

    Shapoval, Tetyana

    2010-01-01

    Local studies of magnetic flux line (vortex) distribution in superconducting thin films and their pinning by natural and artificial defects have been performed using low-temperature magnetic force microscopy (LT-MFM). Taken a 100 nm thin NbN film as an example, the depinning of vortices from natural defects under the influence of the force that the MFM tip exerts on the individual vortex was visualized and the local pinning force was estimated. The good agreement of these results with global transport measurements demonstrates that MFM is a powerful and reliable method to probe the local variation of the pinning landscape. Furthermore, it was demonstrated that the presence of an ordered array of 1-μm-sized ferromagnetic permalloy dots being in a magneticvortex state underneath the Nb film significantly influences the natural pinning landscape of the superconductor leading to commensurate pinning effects. This strong pinning exceeds the repulsive interaction between the superconducting vortices and allows vortex clusters to be located at each dot. Additionally, for industrially applicable YBa 2 Cu 3 O 7-δ thin films the main question discussed was the possibility of a direct correlation between vortices and artificial defects as well as vortex imaging on rough as-prepared thin films. Since the surface roughness (droplets, precipitates) causes a severe problem to the scanning MFM tip, a nanoscale wedge polishing technique that allows to overcome this problem was developed. Mounting the sample under a defined small angle results in a smooth surface and a monotonic thickness reduction of the film along the length of the sample. It provides a continuous insight from the film surface down to the substrate with surface sensitive scanning techniques. (orig.)

  3. Microwave dynamics of YBCO bi-epitaxial Josephson structures

    DEFF Research Database (Denmark)

    Constantinian, K. Y.; Ovsyannikov, G. A.; Mashtakov, A. D.

    1996-01-01

    The processes of interaction of microwaves (frequency View the MathML source) with a single high-Tc superconducting YBa2Cu3Ox (YBCO) bi-epitaxial grain-boundary junction and with an array of two junctions connected in series, have been investigated experimentally at temperatures T = 4.2− 77 K......, as well as the subharmonic detector response at weak magnetic fields φ microwave field induced frequency synchronization of two series connected bi-epitaxial YBCO junctions....

  4. Quasi-One-Dimensional Intermittent Flux Behavior in Superconducting Films

    Directory of Open Access Journals (Sweden)

    A. J. Qviller

    2012-01-01

    Full Text Available Intermittent filamentary dynamics of the vortex matter in superconductors is found in films of YBa_{2}Cu_{3}O_{7-δ} deposited on tilted substrates. Deposition of this material on such substrates creates parallel channels of easy flux penetration when a magnetic field is applied perpendicular to the film. As the applied field is gradually increased, magneto-optical imaging reveals that flux penetrates via numerous quasi-one-dimensional jumps. The distribution of flux avalanche sizes follows a power law, and data collapse is obtained by finite-size scaling, with the depth of the flux front used as crossover length. The intermittent behavior shows no threshold value in the applied field, in contrast to conventional flux jumping. The results strongly suggest that the quasi-one-dimensional flux jumps are of a different nature than the thermomagnetic dendritic (branching avalanches that are commonly found in superconducting films.

  5. Optimal design of superconducting fault detector for superconductor triggered fault current limiters

    International Nuclear Information System (INIS)

    Yim, S.-W.; Kim, H.-R.; Hyun, O.-B.; Sim, J.; Park, K.B.; Lee, B.W.

    2008-01-01

    We have designed and tested a superconducting fault detector (SFD) for a 22.9 kV superconductor triggered fault current limiters (STFCLs) using Au/YBCO thin films. The SFD is to detect a fault and commutate the current from the primary path to the secondary path of the STFCL. First, quench characteristics of the Au/YBCO thin films were investigated for various faults having different fault duration. The rated voltage of the Au/YBCO thin films was determined from the results, considering the stability of the Au/YBCO elements. Second, the recovery time to superconductivity after quench was measured in each fault case. In addition, the dependence of the recovery characteristics on numbers and dimension of Au/YBCO elements were investigated. Based on the results, a SFD was designed, fabricated and tested. The SFD successfully detected a fault current and carried out the line commutation. Its recovery time was confirmed to be less than 0.5 s, satisfying the reclosing scheme in the Korea Electric Power Corporation (KEPCO)'s power grid

  6. Hall effect of K-doped superconducting thin films

    Energy Technology Data Exchange (ETDEWEB)

    Son, Eunseon; Lee, Nam Hoon; Kang, Won Nam [Dept. of physics, Sungkyunkwan University, Suwon (Korea, Republic of); Hwang, Tae Jong; Kim, Dong Ho [Dept. of physics, Yeungnam University, Gyeongsan(Korea, Republic of)

    2013-09-15

    We have studied Hall effect for potassium (K)-doped BaFe{sub 2}As{sub 2}superconducting thin films by analyzing the relation between the longitudinal resistivity (ρ{sub xy}) and the Hall resistivity (ρ{sub xy}). The thin films used in this study were fabricated on Al{sub O3} (000l) substrates by using an ex-situ pulsed laser deposition (PLD) technique under a high-vacuum condition of ∼10{sup -6} Torr. The samples showed the high superconducting transition temperatures (T{sub C}) of ∼40 K. The ρ{sub xx} and ρ{sub xy}the for K-doped BaFeAs{sub 2} thin films were measured by using a physical property measurement system (PPMS) with a temperature sweep (T-sweep) mode at an applied current density of 100 A/cm{sup 2} and at magnetic fields from 0 up to 9 T. We report the T-sweep results of the ρ{sub xx} and the ρ{sub xy} to investigate Hall scaling behavior on the basis of the relation of ρ{sub xy} = A(ρ{sub xy}){sup β}. The ρ{sub xx} values are 3.0 ± 0.2 in the c-axis-oriented K-doped BaFeAs{sub 2} thin films, whereas the thin films with various oriented-directions like a polycrystal showed slightly lower β than that of c-axis-oriented thin films. Interestingly, the β value is decreased with increasing magnetic fields.

  7. Quantitative MFM on superconducting thin films

    Energy Technology Data Exchange (ETDEWEB)

    Stopfel, Henry; Vock, Silvia; Shapoval, Tetyana; Neu, Volker; Wolff, Ulrike; Haindl, Silvia; Engelmann, Jan; Schaefer, Rudolf; Holzapfel, Bernhard; Schultz, Ludwig [IFW Dresden, Institute for Metallic Material (Germany); Inosov, Dmytro S. [Max Planck Institute for Solid State Research, Stuttgart (Germany)

    2012-07-01

    Quantitative interpretation of magnetic force microscopy (MFM) data is a challenge, because the measured signal is a convolution between the magnetization of the tip and the stray field emanated by the sample. It was established theoretically that the field distribution just above the surface of the superconductor can be well approximated by the stray field of a magnetic monopole. The description of the MFM tip, however, needs a second approximation. The temperature-dependent vortex-distribution images on a NbN thin film were fitted using two different tip models. Firstly, the magnetic tip was assumed to be a monopole that leads to the simple monopole-monopole model for the tip-sample interaction force. Performing a 2D fitting of the data with this model, we extracted λ, Δ and the vortex pinning force. Secondly, a geometrical model was applied to calculate the tip-transfer-function of the MFM tip using the numerical BEM method.

  8. Overgrowth of cracks in YBa{sub 2}Cu{sub 3}O{sub 6+δ}-thin films grown on SrTiO{sub 3}- and Al{sub 2}O{sub 3}-substrates

    Energy Technology Data Exchange (ETDEWEB)

    Ackermann, Kai; Haenisch, Jens; Holzapfel, Bernhard [Institut fuer Technische Physik, Karlsruher Institut fuer Technologie, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

    2016-07-01

    High temperature superconducting materials like REBCO-thin films offer a wide range of applications like superconducting transformers, cables, coils or fault current limiters. Although the number of applications is increasing the REBCO-coated conductor length is still limited due to substrate and thin film fabrication defects. In order to improve the manufacturing processes of REBCO-coated conductors the growth behavior of REBCO-thin films on defective or broken substrate surfaces has to be understood. Therefore we investigated the structural and electronic properties of YBCO-thin films grown on cracked SrTiO{sub 3}- and Al{sub 2}O{sub 3}-substrates. The YBCO-films were prepared by using metalorganic (MOD) and pulsed laser deposition (PLD). Structural and electronic properties of the YBCO-films were investigated by using x-ray diffractometry, atomic force microscopy, scanning electron microscopy and temperature- and magnetic field-dependent conductivity measurements.

  9. Superconducting properties of Pb82Bi18 films controlled by ferromagnetic nanowire arrays

    International Nuclear Information System (INIS)

    Ye Zuxin; Lyuksyutov, Igor F; Wu Wenhao; Naugle, Donald G

    2011-01-01

    The superconducting properties of Pb 82 Bi 18 alloy films deposited on ferromagnetic nanowire arrays have been investigated. Ferromagnetic Co or Ni nanowires are first electroplated into the columnar pores of anodic aluminum oxide (AAO) membranes. Superconducting Pb 82 Bi 18 films are then quench condensed onto the polished surface of the AAO membranes filled with magnetic nanowires. A strong dependence of the Pb 82 Bi 18 superconducting properties on the ratio of the superconducting film thickness to the magnetic nanowire diameter and material variety was observed.

  10. Superconducting properties of Pb82Bi18 films controlled by ferromagnetic nanowire arrays

    Science.gov (United States)

    Ye, Zuxin; Lyuksyutov, Igor F.; Wu, Wenhao; Naugle, Donald G.

    2011-02-01

    The superconducting properties of Pb82Bi18 alloy films deposited on ferromagnetic nanowire arrays have been investigated. Ferromagnetic Co or Ni nanowires are first electroplated into the columnar pores of anodic aluminum oxide (AAO) membranes. Superconducting Pb82Bi18 films are then quench condensed onto the polished surface of the AAO membranes filled with magnetic nanowires. A strong dependence of the Pb82Bi18 superconducting properties on the ratio of the superconducting film thickness to the magnetic nanowire diameter and material variety was observed.

  11. Superconducting Properties of Lead-Bismuth Films Controlled by Ferromagnetic Nanowire Arrays

    Science.gov (United States)

    Ye, Zuxin; Lyuksyutov, Igor F.; Wu, Wenhao; Naugle, Donald G.

    2011-03-01

    Superconducting properties of lead-bismuth (82% Pb and 18% Bi) alloy films deposited on ferromagnetic nanowire arrays have been investigated. Ferromagnetic Co or Ni nanowires are first electroplated into the columnar pores of anodic aluminum oxide (AAO) membranes. Superconducting Pb 82 Bi 18 films are then quench-condensed onto the polished surface of the AAO membranes filled with magnetic nanowires. A strong dependence of the Pb 82 Bi 18 superconducting properties on the ratio of the superconducting film thickness to the magnetic nanowire diameter and the material variety was observed.

  12. Growth of Highly Epitaxial YBa2Cu3O7-δ Films from a Simple Propionate-Based Solution

    DEFF Research Database (Denmark)

    Yue, Zhao; Torres, Pol; Tang, Xiao

    2015-01-01

    Intensive investigations have been conducted to develop epitaxial oxide thin films with superior electromagnetic performance by low-cost chemical solution deposition routes. In this paper, a novel propionate-based precursor solution without involving any other additive was proposed and employed...... to grow superconducting YBa2Cu3O7-δ (YBCO) films on LaAlO3 (LAO) single crystals. The precursor solutions are stable with a long shelf life of up to several months. Since the primary compositions are propionates after evaporating the solvent, the toxic reagents and evolved gases during solution synthesis...... and heat treatment can be eliminated completely. In this process, rapid pyrolysis and high conversation rate can also be achieved during growth of YBCO films in comparison with the conventional trifluoroacetate metal organic deposition routes. Remarkably, a 210 nm YBCO film exhibits high superconducting...

  13. Enhanced pinning in superconducting thin films with graded pinning landscapes

    Science.gov (United States)

    Motta, M.; Colauto, F.; Ortiz, W. A.; Fritzsche, J.; Cuppens, J.; Gillijns, W.; Moshchalkov, V. V.; Johansen, T. H.; Sanchez, A.; Silhanek, A. V.

    2013-05-01

    A graded distribution of antidots in superconducting a-Mo79Ge21 thin films has been investigated by magnetization and magneto-optical imaging measurements. The pinning landscape has maximum density at the sample border, decreasing linearly towards the center. Its overall performance is noticeably superior than that for a sample with uniformly distributed antidots: For high temperatures and low fields, the critical current is enhanced, whereas the region of thermomagnetic instabilities in the field-temperature diagram is significantly suppressed. These findings confirm the relevance of graded landscapes on the enhancement of pinning efficiency, as recently predicted by Misko and Nori [Phys. Rev. B 85, 184506 (2012)].

  14. Josephson soliton oscillators in a superconducting thin film resonator

    DEFF Research Database (Denmark)

    Holm, J.; Mygind, Jesper; Pedersen, Niels Falsig

    1993-01-01

    Josephson soliton oscillators integrated in a resonator consisting of two closely spaced coplanar superconducting microstrips have been investigated experimentally. Pairs of long 1-D Josephson junctions with a current density of about 1000 A/cm2 were made using the Nb-AlOx-Nb trilayer technique....... Different modes of half-wave resonances in the thin-film structure impose different magnetic field configurations at the boundaries of the junctions. The DC I-V characteristic shows zero-field steps with a number of resonator-induced steps. These structures are compared to RF-induced steps generated...

  15. YBa2Cu3O7-x thin films prepared by chemical solution deposition

    International Nuclear Information System (INIS)

    Apetrii, Claudia

    2009-01-01

    The discovery of superconductivity in ceramic materials by Bednorz and Mueller in early 1987, immediately followed by Wu et al., who showed that YBa 2 Cu 3 O 7-x (YBCO) becomes superconducting (92 K) well above the boiling point of nitrogen (77 K) created a great excitement in superconductivity research. Potential applications of high T c -superconductors require large critical currents and high-applied magnetic fields. Effective ways to increase the critical current density at high magnetic fields in YBCO are the introduction of nanoparticles and chemical substitution of yttrium by other rare earth elements. Since low costs and environmental compatibility are essential conditions for the preparation of long length YBCO films, the cost effective chemical solution deposition (CSD) procedure was selected, given that no vacuum technology is required. To reveal the flexibility and the good optimization possibilities of the CSD approach two main processes were chosen for comparison: a fluorine-free method, namely the polymer-metal precursor technique, and a fluorine-based method, the metalorganic deposition (MOD) using the trifluoroacetates (TFA) technique. Sharp transition temperature widths ΔT c of 1.1 K for the polymer metal method, 0.8 K for TFA method and critical current densities J c of ∼3.5 MA/cm 2 shows that high quality YBCO thin films can be produced using both techniques. Especially interesting is the magnetic field dependence of the critical current density J c (B) of the Y(Dy)BCO (80 %) films showing that for the lower magnetic fields the critical current density J c (B) is higher for a standard YBCO film, but at fields higher than 4.5 T the critical current density J c (B) of Y(Dy)BCO is larger than that for the YBCO. Above 8 T, J c (B) of the Y(Dy)BCO film is more than one order of magnitude higher than in pure YBCO film. (orig.)

  16. SmBa2NbO6 Nanopowders, an Effective Percolation Network Medium for YBCO Superconductors

    Directory of Open Access Journals (Sweden)

    S. Vidya

    2013-01-01

    Full Text Available The percolation behavior of superconductor-insulator composite, YBa2Cu3O7–δ, and nano SmBa2NbO2 synthesized by modified combustion technique was studied. Particle size of nano SmBa2NBO6 was determined using transmission electron microscopy. The chemical nonreactivity of nano SmBa2NbO6 with YBCO is evident from the X-Ray diffraction study which makes it a suitable nanoceramic substrate material for high temperature superconducting films. A systematic increase in the sintered density, approaching the optimum value of the insulating nanophase is clearly observed, as the vol.% of YBCO in the composite decreases. SEM micrograph showed uniform distribution of nanopowder among the large clusters of YBCO. The obtained percolation threshold is ~26 vol% of YBCO in the composite. All the composites below the threshold value showed TC(0~92 K even though the room resistivity increases with increase in vol.% of nano SmBa2NbO6. The values of critical exponents obtained matches well with the theoretically expected ones for an ideal superconductor-insulator system.

  17. Specific feature of critical fields of inhomogeneous superconducting films

    International Nuclear Information System (INIS)

    Glazman, L.I.; Dmitrenko, I.M.; Kolin'ko, A.E.; Pokhila, A.S.; Fogel', N.Ya.; Cherkasova, V.G.

    1988-01-01

    Experimental studies on thin vanadium films (d=250-400 A) have revealed anomaly in the temperature dependence of the upper critical field H cparallel (T), when H is parallel to the sample plane. At certain temperature T 0 the dependence H cparallel 2 (T) has a sharp kink separating two linear portions. The anomalous behaviour of H cparallel (T) of thin V films can be accounted for assuming the film separation into two parallel layers having different parameters (critical temperature T c , coherence length ξ, thickness d). At temperatures above and lower T 0 the dependence H cparallel (T) is mainly dependent on the characteristics of only one layer. The kink in the dependence H cparallel 2 (T) is due to a jump-like transition of the superconducting nucleus from one layer to the other at T c . The anomalous behaviour of the dependence H cparallel (T) is also observed in sandwiches consisting of two identical films separated with a high (about 30 A) dielectric interlayer; however, the transition from one linear portion to the other is smooth. In the case of identical films a specific crossover occurs if at T-T c the critical field H cparallel (T) coinsides with that for the layer of doubled thickness, then at lowering temperature H cparallel (T) asymptotically approaches the critical field of one layer. The calculation within the model described provides a good description for the experimental results

  18. Towards Isotropic Vortex Pinning in YBCO Films with Double-doping BHO-Y2O3 and BZO-Y2O3 Artificial Pining Centers

    Science.gov (United States)

    Gautam, Bibek; Sebastian, Mary Ann; Chen, Shihong; Haugan, Timothy; Chen, Yanbin; Xing, Zhongwen; Prestigiacomo, Joseph; Osofsky, Mike; Wu, Judy

    2017-12-01

    Strong and isotropic vortex pinning landscape is demanded for high field applications of YaBa2Cu3O7-x (YBCO) epitaxial thin films. Double-doping (DD) of artificial pinning centers (APCs) of mixed morphologies has been identified as a viable approach for this purpose. This work presents a comparative study on the transport critical current density J c (H, θ) of 3.0 vol.%Y2O3+2.0 (or 6.0) vol.% BaZrO3 (BZO DD) and 3.0 vol.%Y2O3+ 2.0 (or 6.0) vol.% BaHfO3 (BHO DD) films. Based on the elastic strain model, BaHfO3 (BHO) nanorods have lower rigidity than their BaZrO3 (BZO) counterparts, which means their c-axis alignment is more susceptible to the local strain generated by the secondary dopant of Y2O3. Considering the increasing strain field with higher BZO (or BHO doping), the higher susceptibility may result in a large portion of the BHO APCs moving away from perfect c-axis alignment and enhancing isotropic pinning with respect to the H orientation. This is confirmed since the BHO DD films illustrate a less pronounced J c peak at H//c-axis and hence more isotropic J c(θ) than their BZO DD counterparts. At 9.0 T, the variation of the J c across the entire θ range (0-90 degree) is less than 18% for the BHO DD film, in contrast to about 100% for the 2.0 vol.% BZO DD counterpart. At the higher BHO concentration of 6.0 vol.%, this higher tunability of the Y2O3 leads to increased ab-plane aligned BHO APCs and hence enhanced J c at H//ab-plane.

  19. Thin Film Approaches to the SRF Cavity Problem: Fabrication and Characterization of Superconducting Thin Films

    Science.gov (United States)

    Beringer, Douglas B.

    Superconducting Radio Frequency (SRF) cavities are responsible for the acceleration of charged particles to relativistic velocities in most modern linear accelerators, such as those employed at high-energy research facilities like Thomas Jefferson National Laboratory's CEBAF and the LHC at CERN. Recognizing SRF as primarily a surface phenomenon enables the possibility of applying thin films to the interior surface of SRF cavities, opening a formidable tool chest of opportunities by combining and designing materials that offer greater benefit. Thus, while improvements in radio frequency cavity design and refinements in cavity processing techniques have improved accelerator performance and efficiency - 1.5 GHz bulk niobium SRF cavities have achieved accelerating gradients in excess of 35 MV/m - there exist fundamental material bounds in bulk superconductors limiting the maximally sustained accelerating field gradient (approximately 45 MV/m for Niobium) where inevitable thermodynamic breakdown occurs. With state of the art niobium based cavity design fast approaching these theoretical limits, novel material innovations must be sought in order to realize next generation SRF cavities. One proposed method to improve SRF performance is to utilize thin film superconducting-insulating-superconducting (SIS) multilayer structures to effectively magnetically screen a bulk superconducting layer such that it can operate at higher field gradients before suffering critically detrimental SRF losses. This dissertation focuses on the production and characterization of thin film superconductors for such SIS layers for radio-frequency applications.

  20. Thin Film Approaches to the SRF Cavity Problem Fabrication and Characterization of Superconducting Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Beringer, Douglas [College of William and Mary, Williamsburg, VA (United States)

    2017-08-01

    Superconducting Radio Frequency (SRF) cavities are responsible for the acceleration of charged particles to relativistic velocities in most modern linear accelerators, such as those employed at high-energy research facilities like Thomas Jefferson National Laboratory’s CEBAF and the LHC at CERN. Recognizing SRF as primarily a surface phenomenon enables the possibility of applying thin films to the interior surface of SRF cavities, opening a formidable tool chest of opportunities by combining and designing materials that offer greater performance benefit. Thus, while improvements in radio frequency cavity design and refinements in cavity processing techniques have improved accelerator performance and efficiency – 1.5 GHz bulk niobium SRF cavities have achieved accelerating gradients in excess of 35 MV/m – there exist fundamental material bounds in bulk superconductors limiting the maximally sustained accelerating field gradient (≈ 45 MV/m for Nb) where inevitable thermodynamic breakdown occurs. With state of the art Nb based cavity design fast approaching these theoretical limits, novel material innovations must be sought in order to realize next generation SRF cavities. One proposed method to improve SRF performance is to utilize thin film superconducting-insulating-superconducting (SIS) multilayer structures to effectively magnetically screen a bulk superconducting layer such that it can operate at higher field gradients before suffering critically detrimental SRF losses. This dissertation focuses on the production and characterization of thin film superconductors for such SIS layers for radio frequency applications. Correlated studies on structure, surface morphology and superconducting properties of epitaxial Nb and MgB2 thin films are presented.

  1. Shot noise in YBCO bicrystal Josephson junctions

    DEFF Research Database (Denmark)

    Constantinian, K.Y.; Ovsyannikov, G.A.; Borisenko, I.V.

    2003-01-01

    We measured spectral noise density in YBCO symmetric bicrystal Josephson junctions on sapphire substrates at bias voltages up to 100 mV and T 4.2 K. Normal state resistance of the Josephson junctions, R-N = 20-90 Omega and ICRN up to 2.2 mV have been observed in the experimental samples. Noise...... may explain the experimentally measured linewidth broadening of Josephson oscillations at mm and submm wave frequencies in high-Tc superconducting junctions. Experimental results are discussed in terms of bound states existing at surfaces of d-wave superconducting electrodes....

  2. YBa2Cu3O(7-x) based superconducting thin films by multitarget sputtering

    International Nuclear Information System (INIS)

    Bouteloup, E.; Mercey, B.; Poullain, G.; Brousse, T.; Murray, H.; Raveau, B.

    1990-01-01

    This paper reports a new technique to prepare superconducting YBa 2 Cu 3 O (7-x) thin films. The multitarget sputtering apparatus described below allows the simultaneous and reproducible production of numerous films with a metallic composition close to Y 17% Ba 33% Cu 50% . Superconducting films (R = 0) at 80 K have been produced on polycrystalline zirconia substrates after a high temperature annealing [fr

  3. Enhancement of critical current density of YBa2Cu3O7-δ thin films by nanoscale CeO2 pretreatment of substrate surfaces

    International Nuclear Information System (INIS)

    Cui, X.M.; Liu, G.Q.; Wang, J.; Huang, Z.C.; Zhao, Y.T.; Tao, B.W.; Li, Y.R.

    2007-01-01

    YBa 2 Cu 3 O 7-δ (YBCO) films were prepared on single-crystal SrTiO 3 substrates with metal-organic deposition using trifluoroacetates (TFA-MOD). Positive results have been acquired in controlled study to investigate the effects of substrate surface modification on the growth-induced flux-pinning nanostructures in YBCO films. Nanoscale CeO 2 particles were applied to single-crystal SrTiO 3 substrate surfaces using pulsed laser deposition before YBCO precursors coating. Superconducting properties of the YBCO films grown on the controlled CeO 2 -modified substrates have shown substantial improvement in the critical current densities (J c ) at 77 K over those grown on untreated substrates in almost all the field (78% increment at 1 T, 77 K). We think the reason is that the CeO 2 nanoparticles act as pinning centers

  4. Transport AC losses in YBCO coated conductors

    Energy Technology Data Exchange (ETDEWEB)

    Majoros, M [Ohio State University, Columbus, OH 43210 (United States); Ye, L [IRC in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Velichko, A V [IRC in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Coombs, T A [IRC in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Sumption, M D [Ohio State University, Columbus, OH 43210 (United States); Collings, E W [Ohio State University, Columbus, OH 43210 (United States)

    2007-09-15

    Transport AC loss measurements have been made on YBCO-coated conductors prepared on two different substrate templates-RABiTS (rolling-assisted biaxially textured substrate) and IBAD (ion-beam-assisted deposition). RABiTS samples show higher losses compared with the theoretical values obtained from the critical state model, with constant critical current density, at currents lower than the critical current. An origin of this extra AC loss was demonstrated experimentally by comparison of the AC loss of two samples with different I-V curves. Despite a difference in I-V curves and in the critical currents, their measured losses, as well as the normalized losses, were practically the same. However, the functional dependence of the losses was affected by the ferromagnetic substrate. An influence of the presence of a ferromagnetic substrate on transport AC losses in YBCO film was calculated numerically by the finite element method. The presence of a ferromagnetic substrate increases transport AC losses in YBCO films depending on its relative magnetic permeability. The two loss contributions-transport AC loss in YBCO films and ferromagnetic loss in the substrate-cannot be considered as mutually independent.

  5. Structure/Property Relationships for Sol-gel Derived YBa2Cu3O7-d and SrTiO3 Films

    Science.gov (United States)

    Dawley, Jeff; Clem, Paul; Siegal, Michael; Overmyer, Don

    2001-03-01

    Solution deposition of c-axis oriented YBa2Cu3O7-d (YBCO) films on buffered RABiT substrates is a potential method for rapid, low cost production of superconducting tapes for power transmission and other applications. For this work, 100-250 nm thick YBCO and SrTiO3 (STO) films have been prepared by spin-coating and dip-coating sol-gel solutions onto LaAlO3 (100) and RABiT Ni (200) substrates. Biaxially textured STO coatings have been deposited on LaAlO3 and RABiT Ni by using a "templating" technique and controlling growth temperature and pO2. YBCO films grown on STO coated LaAlO3 possess comparable superconducting properties to YBCO films grown directly on LaAlO3 ( 1 MA/cm2 at 77K), indicating that a high quality STO layer does not degrade the crystalline quality of the YBCO. The effects of processing parameters on the STO buffer layer and novel processing techniques for decreasing the processing time and simplifying the integration of sol-gel YBCO with Ni substrates will be discussed. Sandia is a multiprogram laboratory operated by Sandia Corp., a Lockheed Martin Company, for the US Dept. Of Energy under contract DE-AC04-94A185000.

  6. Measurements and removal of substrate effects on the microwave surface impedance of YBCO films on SrTiO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Pompeo, N [Dipartimento di Fisica ' E Amaldi' and Unita CNISM, Universita Roma Tre, Via dellaVasca Navale 84, 00146 Rome (Italy); Muzzi, L [Dipartimento di Fisica ' E Amaldi' and Unita CNISM, Universita Roma Tre, Via dellaVasca Navale 84, 00146 Rome (Italy); Galluzzi, V [ENEA-Frascati, Via Enrico Fermi 45, 00044 Frascati, Rome (Italy); Marcon, R [Dipartimento di Fisica ' E Amaldi' and Unita CNISM, Universita Roma Tre, Via dellaVasca Navale 84, 00146 Rome (Italy); Silva, E [Dipartimento di Fisica ' E Amaldi' and Unita CNISM, Universita Roma Tre, Via dellaVasca Navale 84, 00146 Rome (Italy)

    2007-10-15

    We reconsider the problem of the measurements of the microwave complex surface impedance in thin superconducting films deposited on SrTiO{sub 3} substrates. We perform measurements of the complex surface impedance Z{sub s}' = R{sub s}'+i{delta}X{sub s}' of thin YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} films deposited by laser ablation on SrTiO{sub 3} substrates. The typical oscillations due to the strong temperature variation of the SrTiO{sub 3} permittivity are confirmed in R{sub s}' and observed in {delta}X{sub s}'. The effects of the SrTiO{sub 3} substrate are evident even well below the superconducting transition temperature of YBa{sub 2}Cu{sub 3}O{sub 7-{delta}}. Similarly to previous works, we describe the overall response in terms of impedance transformations. We extend the known results by (i) considering the measurements of the imaginary part (ii) comparing the measurements to the absolute dc resistivity measured on the same sample, and (iii) suggesting a method for measuring the intrinsic thin film surface impedance by adjusting the substrate impedance. To demonstrate the feasibility of microwave measurements of intrinsic properties of films grown onto SrTiO{sub 3} substrates, we check the proposed method by measuring the field dependent surface impedance before and after removal of the substrate resonance.

  7. Response of high Tc superconducting Josephson junction to nuclear radiation

    International Nuclear Information System (INIS)

    Ding Honglin; Zhang Wanchang; Zhang Xiufeng

    1992-10-01

    The development of nuclear radiation detectors and research on high T c superconducting nuclear radiation detectors are introduced. The emphases are the principle of using thin-film and thick-film Josephson junctions (bridge junction) based on high T c YBCO superconductors to detect nuclear radiation, the fabrication of thin film and thick-film Josephson junction, and response of junction to low energy gamma-rays of 59.5 keV emitted from 241 Am and beta-rays of 546 keV. The results show that a detector for measuring nuclear radiation spectrum made of high T c superconducting thin-film or thick-film, especially, thick-film Josephson junction, certainly can be developed

  8. Superconducting niobium nitride films deposited by unbalanced magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Olaya, J.J. [Departamento de Ingenieria Mecanica y Mecatronica, Universidad Nacional de Colombia, Ciudad Universitaria, Carrera 30 Numero 45-03, Bogota (Colombia); Huerta, L. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Circuito exterior s/n, CU Coyoacan, Mexico D.F. 04510 (Mexico); Rodil, S.E. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Circuito exterior s/n, CU Coyoacan, Mexico D.F. 04510 (Mexico)], E-mail: ser42@iim.unam.mx; Escamilla, R. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Circuito exterior s/n, CU Coyoacan, Mexico D.F. 04510 (Mexico)

    2008-10-01

    Niobium nitride (NbN) thin films were deposited under different configurations of the magnetic field using a magnetron sputtering system. The magnetic field configuration varied from balanced to unbalanced leading to different growth conditions and film properties. The aim of the paper was to identify correlations between deposition conditions, film properties and the electrical properties, specially the superconductive critical temperature (T{sub C}). The results suggested that there is a critical deposition condition, having an optimum ion-atom arrival ratio that promotes a well ordered and textured nanocrystalline structure (cubic phase) with the minimum residual stress and only under this condition a high critical temperature (16K) was obtained. Lower T{sub C} values around 12K were obtained for the NbN samples having a lower degree of structural perfection and texture, and a larger fraction of intergranular voids. On the other hand, analysis of valence-band spectra showed that the contribution of the Nb 4d states remained essentially constant while the higher T{sub C} was correlated to a higher contribution of the N 2p states.

  9. Superconducting niobium nitride films deposited by unbalanced magnetron sputtering

    International Nuclear Information System (INIS)

    Olaya, J.J.; Huerta, L.; Rodil, S.E.; Escamilla, R.

    2008-01-01

    Niobium nitride (NbN) thin films were deposited under different configurations of the magnetic field using a magnetron sputtering system. The magnetic field configuration varied from balanced to unbalanced leading to different growth conditions and film properties. The aim of the paper was to identify correlations between deposition conditions, film properties and the electrical properties, specially the superconductive critical temperature (T C ). The results suggested that there is a critical deposition condition, having an optimum ion-atom arrival ratio that promotes a well ordered and textured nanocrystalline structure (cubic phase) with the minimum residual stress and only under this condition a high critical temperature (16K) was obtained. Lower T C values around 12K were obtained for the NbN samples having a lower degree of structural perfection and texture, and a larger fraction of intergranular voids. On the other hand, analysis of valence-band spectra showed that the contribution of the Nb 4d states remained essentially constant while the higher T C was correlated to a higher contribution of the N 2p states

  10. Superconductivity of a Sn film controlled by an array of Co nanowires

    Science.gov (United States)

    Wei, Z.; Ye, Z.; Rathnayaka, K. D. D.; Lyuksyutov, I. F.; Wu, W.; Naugle, D. G.

    2012-09-01

    Superconducting properties of a hybrid structure composed of ferromagnetic Co nanowire arrays and a superconducting Sn film have been investigated. Ordered Co nanowires arrays with 60 nm, 150 nm and 200 nm diameter were electroplated into the pores of self organized Anodic Aluminum Oxide (AAO) membranes. Hysteretic dependence of the Sn film superconducting properties on applied magnetic field and critical current enhancement at moderate fields has been observed. This behavior strongly depends on the ratio of the Sn film thickness to the Co nanowire diameter.

  11. Superconductivity of a Sn film controlled by an array of Co nanowires

    International Nuclear Information System (INIS)

    Wei, Z.; Ye, Z.; Rathnayaka, K.D.D.; Lyuksyutov, I.F.; Wu, W.; Naugle, D.G.

    2012-01-01

    Superconducting properties of a hybrid structure composed of ferromagnetic Co nanowire arrays and a superconducting Sn film have been investigated. Ordered Co nanowires arrays with 60 nm, 150 nm and 200 nm diameter were electroplated into the pores of self organized Anodic Aluminum Oxide (AAO) membranes. Hysteretic dependence of the Sn film superconducting properties on applied magnetic field and critical current enhancement at moderate fields has been observed. This behavior strongly depends on the ratio of the Sn film thickness to the Co nanowire diameter.

  12. Stoichiometry and superconductive properties of YBaCuO films deposited by spray pyrolysis

    International Nuclear Information System (INIS)

    Conde-Gallardo, A.; Falcony, C.; Ortiz, A.

    1994-01-01

    The dependence of the stoichiometry and the superconducting characteristics of YBaCuO films deposited by spray pyrolysis on the spraying solution composition and the deposition conditions is reported. It has been found that a proper optimization of the starting materials concentration in the spraying solution results in superconducting films with zero resistance temperature of 91 K and a transition to superconducting state within a 3 K range. X-ray diffraction and resistance vs temperature measurements have been used to monitor the crystal composition and the conductive characteristics of the films as a function of the spraying solution composition and the deposition parameters

  13. Y-Ba-Cu-O superconducting thin films by simultaneous or sequential evaporation

    International Nuclear Information System (INIS)

    Mogro-Campero, A.; Hunt, B.D.; Turner, L.G.; Burrell, M.C.; Balz, W.E.

    1988-01-01

    Superconducting thin films of Y-Ba-Cu-O near the 1:2:3 stoichiometry were produced by simultaneous (coevaporation) and sequential (multilayer) evaporation in the same evaporator. The best film obtained on yttria-stabilized zirconia (YSZ) had a superconducting onset temperature of 104 K, a midpoint T/sub c/ of 92 K, and zero resistance at T≤74 K. Stoichiometry was deduced by inductively coupled plasma emission spectroscopy, and elemental depth profiles were obtained by x-ray photoelectron spectroscopy. Film stoichiometry changes only near the film/substrate boundary for films on YSZ. Films on Si/SiO 2 were not superconducting; depth profiling shows severe changes of film composition with depth. A major theme of this work is process reproducibility, which was found to be poor for coevaporation but improved considerably for sequential evaporation

  14. Loss mechanisms in superconducting thin film microwave resonators

    Energy Technology Data Exchange (ETDEWEB)

    Goetz, Jan, E-mail: jan.goetz@wmi.badw.de; Haeberlein, Max; Wulschner, Friedrich; Zollitsch, Christoph W.; Meier, Sebastian; Fischer, Michael; Fedorov, Kirill G.; Menzel, Edwin P. [Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching (Germany); Physik-Department, Technische Universität München, 85748 Garching (Germany); Deppe, Frank; Eder, Peter; Xie, Edwar; Gross, Rudolf, E-mail: rudolf.gross@wmi.badw.de [Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching (Germany); Physik-Department, Technische Universität München, 85748 Garching (Germany); Nanosystems Initiative Munich (NIM), Schellingstraße 4, 80799 München (Germany); Marx, Achim [Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching (Germany)

    2016-01-07

    We present a systematic analysis of the internal losses of superconducting coplanar waveguide microwave resonators based on niobium thin films on silicon substrates. In particular, we investigate losses introduced by Nb/Al interfaces in the center conductor, which is important for experiments where Al based Josephson junctions are integrated into Nb based circuits. We find that these interfaces can be a strong source for two-level state (TLS) losses, when the interfaces are not positioned at current nodes of the resonator. In addition to TLS losses, for resonators including Al, quasiparticle losses become relevant above 200 mK. Finally, we investigate how losses generated by eddy currents in conductive material on the backside of the substrate can be minimized by using thick enough substrates or metals with high conductivity on the substrate backside.

  15. Studies of the Superconducting Transition in the Mo/Au-Bilayer Thin Films

    Science.gov (United States)

    Sadleir, John; Smith, Stephen; Iyomoto, naoko; Bandler, Simon; Chervenak, Jay; Brown, Ari; Brekowsky, Regis; Kilbourne, Caroline; Robinson, Ian

    2007-01-01

    At NASA Goddard, microcalorimeter arrays using superconducting transition edge sensor thermometers (TESs) are under development for high energy resolution X-ray astrophysics applications. We report on our studies of the superconducting transition in our Mo/Au-bilayer TES films including: low current measurements of the superconducting bilayer's resistance transition versus temperature on pixels with different normal metal absorber attachment designs and measured temperature scaling of the critical current and critical magnetic field.

  16. Epitaxial YBa2Cu3O7 on biaxially textured (001) Ni: An approach to high critical current density superconducting tapes

    International Nuclear Information System (INIS)

    Norton, D.P.; Goyal, A.; Budai, J.D.

    1997-01-01

    In-plane aligned, c-axis oriented YBa 2 Cu 3 O 7 (YBCO) films with superconducting critical current densities, J c , as high as 700,000 amperes per square centimeter at 77 kelvin have been grown on thermo-mechanically, rolled-textured (001) Ni tapes using pulsed-laser deposition. Epitaxial growth of oxide buffer layers directly on biaxially textured Ni, formed by recrystallization of cold-rolled pure Ni, enables the growth of 1.5 micrometer-thick YBCO films with superconducting properties that are comparable to those observed for epitaxial films on single crystal oxide substrates. This result represents a viable approach for producing long-length superconducting tapes for high current, high field applications at 77 kelvin

  17. YBCO coated conductors by reactive thermal co-evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Schmatz, U.; Hoffmann, Ch.; Bauer, M.; Metzger, R.; Berberich, P.; Kinder, H. [Technische Univ. Muenchen, Garching (Germany). Physik-Department

    2001-12-01

    Coated tape conductors of YBCO require a deposition process allowing to obtain a high volume growth rate in order to produce long lengths of tape in a reasonable amount of time. We present our tape coating system where 15 parallel loops of travelling tape of 1 cm width can be coated simultaneously by reactive thermal co-evaporation. For high critical current densities, in-plane alignment of the YBCO film is necessary. Inclined substrate deposition (ISD) is a technique that allows to deposit in-plane oriented buffer layers suitable for YBCO growth at high deposition rates. We present results obtained for YBCO films grown on MgO-ISD buffer layers deposited by e-gun evaporation onto metallic tape substrates. (orig.)

  18. Superconductivity

    International Nuclear Information System (INIS)

    Taylor, A.W.B.; Noakes, G.R.

    1981-01-01

    This book is an elementray introduction into superconductivity. The topics are the superconducting state, the magnetic properties of superconductors, type I superconductors, type II superconductors and a chapter on the superconductivity theory. (WL)

  19. Comparison of water degradation of YBaCuO superconducting films made from different structures

    International Nuclear Information System (INIS)

    Chang, C.; Tsai, J.A.

    1988-01-01

    Immersion of YBaCuO superconducting films in water has shown a large difference in degradation between structures with and without silver. For the structures containing silver layers and depositing at a high temperature, superconducting films with zero resistance at 87 K remain superconductive at 77 K after 5 h immersion in water, with an increase in room-temperature film resistance by a factor of 4; the contact resistance remains low after 60 h of immersion, allowing the measurement at low temperatures. For the structures containing no silver and depositing at room temperature, the contact resistance rapidly increases with immersion times, making the measurement at 77 K difficult after 5 min of immersion. Changes in the sharpness of the superconductive transition, and structures of the films due to the water immersion are also compared

  20. High-Tc Superconducting Thick-Film Spiral Magnet: Development and Characterization of a Single Spiral Module

    National Research Council Canada - National Science Library

    McGinnis, W

    1997-01-01

    The objective of this project was to make characterized and numerically model prototype modules of a new type of superconducting electromagnet based on stacked spirals of superconducting thick films...

  1. Heat conduction and thermal stabilization in YBCO tape

    Indian Academy of Sciences (India)

    Yttrium barium copper oxide (YBCO) based 2G/3G tech- nical superconductors ... off-normal scenarios, these superconductors do exceed in an irreversible fashion .... ler G 2007 Factory testing of a 36·5 MW high temperature superconducting ...

  2. Magnetic shield effect simulation of superconducting film shield covering directly coupled HTS dc-SQUID magnetometer

    International Nuclear Information System (INIS)

    Terauchi, N.; Noguchi, S.; Igarashi, H.

    2011-01-01

    A superconducting film shield over a SQUID ring improves the robustness of the SQUID with respect to magnetic noise. Supercurrent in the SQUID magnetometer and the superconducting film shield were simulated. The superconducting film shield reduces the influence of the external magnetic field on the SQUID ring. An HTS SQUID is a high sensitive magnetic sensor. In recent years, the HTS SQUID is widely used in various applications. In some applications, high robustness with respect to magnetic noise is required to realize stable operation at outside of a magnetic shielding room. The target of this paper is a directly coupled HTS dc-SQUID magnetometer. To enhance the robustness of the SQUID magnetometer, use of a superconducting thin film shield has been proposed. The magnetic field directly penetrating the SQUID ring causes the change of the critical current of Josephson junction, and then the SQUID magnetometer transitions into inoperative state. In order to confirm the magnetic shield effect of the superconducting film shield, electromagnetic field simulation with 3D edge finite element method was performed. To simulate the high temperature superconductor, E-J characteristics and c-axis anisotropy are considered. To evaluate the effect of the superconducting film shield, an external magnetic field which is supposed to be a magnetic noise is applied. From the simulation results, the time transition of the magnetic flux penetrating the SQUID ring is investigated and the effect of the superconducting film shield is confirmed. The amplitude of the magnetic flux penetrating the SQUID ring can be reduced to about one-sixth since the superconducting film shield prevents the magnetic noise from directly penetrating the SQUID ring.

  3. High quality superconducting titanium nitride thin film growth using infrared pulsed laser deposition

    Science.gov (United States)

    Torgovkin, A.; Chaudhuri, S.; Ruhtinas, A.; Lahtinen, M.; Sajavaara, T.; Maasilta, I. J.

    2018-05-01

    Superconducting titanium nitride (TiN) thin films were deposited on magnesium oxide, sapphire and silicon nitride substrates at 700 °C, using a pulsed laser deposition (PLD) technique, where infrared (1064 nm) pulses from a solid-state laser were used for the ablation from a titanium target in a nitrogen atmosphere. Structural studies performed with x-ray diffraction showed the best epitaxial crystallinity for films deposited on MgO. In the best films, superconducting transition temperatures, T C, as high as 4.8 K were observed, higher than in most previous superconducting TiN thin films deposited with reactive sputtering. A room temperature resistivity down to ∼17 μΩ cm and residual resistivity ratio up to 3 were observed in the best films, approaching reported single crystal film values, demonstrating that PLD is a good alternative to reactive sputtering for superconducting TiN film deposition. For less than ideal samples, the suppression of the film properties were correlated mostly with the unintended incorporation of oxygen (5–10 at%) in the film, and for high oxygen content films, vacuum annealing was also shown to increase the T C. On the other hand, superconducting properties were surprisingly insensitive to the nitrogen content, with high quality films achieved even in the highly nitrogen rich, Ti:N = 40/60 limit. Measures to limit oxygen exposure during deposition must be taken to guarantee the best superconducting film properties, a fact that needs to be taken into account with other deposition methods, as well.

  4. Effect of localized electron states on superconductivity of ultrathin beryllium films

    International Nuclear Information System (INIS)

    Tutov, V.I.; Semenenko, E.E.

    1988-01-01

    A wide spectrum of distortions is induced in ultrathin beryllium films of thickness less than 10 A, which are responsible for the system transition from the strong localization state completely suppressing superconductivity (in this case R □ of the layer reaches 97600 Ohm) to the weak localization stae coexisting with superconductivity at comparatively high T c (5 K). The resistance per square R □ of the films decreases more than by an order of magnitude. The superconductivity with T c =1.7 K occurs at rather strong localization, when R □ of the layer is 34000 Ohm

  5. Transport currents along c-axis and (a,b) planes in YBCO single domain materials. Critical current densities and normal-superconducting transitions

    International Nuclear Information System (INIS)

    Porcar, L.; Bourgault, D.; Chaud, X.; Noudem, J.G.; Tournier, R.; Tixador, P.

    1998-01-01

    High transport currents along the (a,b) planes and along the c-axis have been measured in pulsed current of different pseudo-frequencies. Self field losses and transport current of 8000 A (20000 A cm -2 ) have been measured in Y 1 Ba 2 Cu 3 O 7-δ bars textured by the melting zone technique. Critical currents as high as 500 A (90000 A cm -2 ) along the (a,b) planes or 3000 A (7500 A cm -2 ) along the c-axis have been measured. For both orientations, the transition from the normal state to the superconducting state has been observed. Electric field of 1000 V m -1 and study of the superconducting state recovery are reported. (orig.)

  6. Advanced high temperature superconductor film-based process using RABiTS

    International Nuclear Information System (INIS)

    Goyal, A.; Hawsey, R.A.; Hack, J.; Moon, D.

    2000-01-01

    The purpose of this Cooperative Research and Development Agreement (CRADA) between Lockheed Martin Energy Research Corporation (Contractor), Managing contractor for Oak Ridge National Laboratory (ORNL) and Midwest Superconductivity, Inc. (MSI) and Westinghouse Science and Electric Company (WEC) was to develop the basis for a commercial process for the manufacturing of superconducting tape based on the RABiTS technology developed at ORNL. The chosen method for deposition of YBCO films on RABiTS was Metal Organic chemical Vapor Deposition (MOCVD)

  7. A thermally actuated superconducting flux pump

    Energy Technology Data Exchange (ETDEWEB)

    Coombs, Timothy [Engineering Department, Cambridge University, Trumpington Street, Cambridge CB2 1PZ (United Kingdom)], E-mail: tac1000@cam.ac.uk; Hong Zhiyong; Zhu Xiaomin [Engineering Department, Cambridge University, Trumpington Street, Cambridge CB2 1PZ (United Kingdom)

    2008-02-01

    The concept of a superconducting flux pump is relatively straightforward. A small magnetic field repeatedly applied will lead to a much larger field being trapped within the superconductor. This field is limited by the volume of the superconductor and by its critical current but not by the excitation field. Here we will describe a new technique which facilitates the creation of high magnetic fields and where the magnitude of the trapped field is limited by the superconductor not the magnetising field. The technique is demonstrated using measurements taken using samples of bulk YBCO as YBCO has a very high irreversibility field and has the potential to trap high magnetic fields. The technique could be applied to other superconductors such as BSCCO or MgB{sub 2} and in other forms such as thin or thick films.

  8. Application of HTSC-thin films in microwave bandpass filters

    International Nuclear Information System (INIS)

    Jha, A.R.

    1993-01-01

    This paper reveals unique performance capabilities of High-Temperature Superconducting Thin-Film (HTSCTFs) for possible applications in microwave bandpass filters (BPFs). Microwave filters fabricated with HTSCTFs have demonstrated lowest insertion loss, highest rejection, and sharpest skirt selectivity. Thin films of Yttrium Barium Copper Oxide (YBCO), Bismuth Strontium Calcium Copper Oxide (BSCCO) and Thallium Calcium Barium Copper Oxide (TCBCO) will be most attractive for filters

  9. Interface-Induced Zeeman-Protected Superconductivity in Ultrathin Crystalline Lead Films

    Directory of Open Access Journals (Sweden)

    Yi Liu

    2018-04-01

    Full Text Available Two-dimensional (2D superconducting systems are of great importance for exploring exotic quantum physics. The recent development of fabrication techniques has stimulated studies of high-quality single-crystalline 2D superconductors, where intrinsic properties give rise to unprecedented physical phenomena. Here, we report the observation of Zeeman-type spin-orbit interaction protected superconductivity (Zeeman-protected superconductivity in 4-monolayer (ML to 6-ML crystalline Pb films grown on striped incommensurate Pb layers on Si(111 substrates by molecular beam epitaxy. An anomalously large in-plane critical field far beyond the Pauli limit is detected, which can be attributed to the Zeeman-protected superconductivity due to the in-plane inversion symmetry breaking at the interface. Our work demonstrates that, in superconducting heterostructures, the interface can induce Zeeman-type spin-orbit interactions and modulate the superconductivity.

  10. Interface-Induced Zeeman-Protected Superconductivity in Ultrathin Crystalline Lead Films

    Science.gov (United States)

    Liu, Yi; Wang, Ziqiao; Zhang, Xuefeng; Liu, Chaofei; Liu, Yongjie; Zhou, Zhimou; Wang, Junfeng; Wang, Qingyan; Liu, Yanzhao; Xi, Chuanying; Tian, Mingliang; Liu, Haiwen; Feng, Ji; Xie, X. C.; Wang, Jian

    2018-04-01

    Two-dimensional (2D) superconducting systems are of great importance for exploring exotic quantum physics. The recent development of fabrication techniques has stimulated studies of high-quality single-crystalline 2D superconductors, where intrinsic properties give rise to unprecedented physical phenomena. Here, we report the observation of Zeeman-type spin-orbit interaction protected superconductivity (Zeeman-protected superconductivity) in 4-monolayer (ML) to 6-ML crystalline Pb films grown on striped incommensurate Pb layers on Si(111) substrates by molecular beam epitaxy. An anomalously large in-plane critical field far beyond the Pauli limit is detected, which can be attributed to the Zeeman-protected superconductivity due to the in-plane inversion symmetry breaking at the interface. Our work demonstrates that, in superconducting heterostructures, the interface can induce Zeeman-type spin-orbit interactions and modulate the superconductivity.

  11. Microstructure and transport current characterization of YBa2Cu3O7-x thick films prepared by modified solid-liquid melt growth and powder melt process routes

    International Nuclear Information System (INIS)

    Langhorn, J.; McGinn, P.J.

    1999-01-01

    From the characterization of superconducting YBa 2 Cu 3 O 7-x (YBCO) thick films processed by melt texturing on yttria-stabilized zirconia substrates from YBCO precursors it is clear that the properties are highly dependent on the precursor powder. Increased YBCO grain sizes have been induced in thick films processed from by modified solid-liquid melt growth (SLMG) and powder melt (PMP) processes with respect to those processed from pre-reacted YBCO materials. The SLMG and PMP routes utilize precursors consisting of BaCuO 2 -CuO flux material mixed with Y 2 O 3 and Y 2 BaCuO 5 respectively. Cross-sectional analysis of films textured by these routes shows a decreased Y 2 BaCuO 5 size and an increased homogeneity within the matrix with respect to films processed from YBCO powder. Such microstructural improvements lead to an improvement of both the flux pinning and current-carrying characteristics of the processed YBCO films. (author)

  12. Critical current behaviour of YBCO thin films described by vortex pinning on low-angle domain boundaries and vortex creep

    International Nuclear Information System (INIS)

    Golovchanskiy, I.A.; Pan, A.V.; Fedoseev, S.A.; Shcherbakova, O.V.; Dou, S.X.

    2012-01-01

    A pinning potential for vortices was introduced assuming plastic pinning of vortex lattice on chains of out-of-plane individual edge dislocations that form low-angle domain boundaries in high quality YBa 2 Cu 3 O 7 thin films. Using this pinning potential with the classical Kim-Anderson vortex creep approach a model for critical current dependence on field has been successfully developed. The model shows a plausible description of J c (B a ) over the entire field range. Electrical field criterion is incorporated providing the ability to compare measurements made with different criteria (including different measurement techniques). Applicability of this model has been verified by experimental data obtained by direct transport and magnetisation measurements on high quality films grown by pulsed laser deposition. Pinning potential obtained from the fitting procedure is consistent with theoretical predictions. The model showed that the effective pinning landscape changes under influence of external conditions.

  13. Critical Current Properties in Longitudinal Magnetic Field of YBCO Superconductor with APC

    Science.gov (United States)

    Kido, R.; Kiuchi, M.; Otabe, E. S.; Matsushita, T.; Jha, A. K.; Matsumoto, K.

    The critical current density (Jc) properties of the Artificial Pinning Center (APC) introduced YBa2Cu3O7 (YBCO) films in the longitudinal magnetic field were measured. Y2O3 or Y2BaCuO5 (Y211) was introduced as APCs to YBCO, and YBCO films with APC were fabricated on SrTiO3 single crystal substrate. The sizes of Y2O3 and Y211 were 5-10 nm and 10-20 nm, respectively. As a result, Jc enhancement in the longitudinal magnetic field was observed in Y2O3 introduced YBCO films. However, it was not observed in Y211 introduced YBCO films. Therefore, it was considered that Jc properties in the longitudinal magnetic field were affected by introducing of small size APC, and it was necessary that APC does not disturb the current pathway in the superconductor.

  14. Superconductivity

    CERN Document Server

    Poole, Charles P; Farach, Horacio A

    1995-01-01

    Superconductivity covers the nature of the phenomenon of superconductivity. The book discusses the fundamental principles of superconductivity; the essential features of the superconducting state-the phenomena of zero resistance and perfect diamagnetism; and the properties of the various classes of superconductors, including the organics, the buckministerfullerenes, and the precursors to the cuprates. The text also describes superconductivity from the viewpoint of thermodynamics and provides expressions for the free energy; the Ginzburg-Landau and BCS theories; and the structures of the high

  15. Solution processing of YBa2Cu3O7-x thin films

    International Nuclear Information System (INIS)

    Singhal, A.; Paranthaman, M.; Specht, E.D.; Hunt, R.D.; Beach, D.B.; Martin, P.M.; Lee, D.F.

    1997-12-01

    The aim of this work was to develop a non-vacuum chemical deposition technique for YBa 2 Cu 3 O 7-x (YBCO) coated conductors on rolling-assisted biaxially textured substrates (RABiTS). The authors have chosen the metal-organic decomposition (MOD) and sol-gel precursor routes to grow textured YBCO films. In the MOD process, yttrium 2-ethylhexonate, barium neodecanoate, copper 2-ethylhexonate and toluene were used as the starting reagents. YBCO films processed by the MOD method on SrTiO 3 (100) single crystal substrates were consisted of c and a-axis oriented materials. These films also contained some amount of the random phase. The c and a-axis oriented materials were epitaxial on SrTiO 3 substrates. Films have a T c,onset of 89K and the best superconducting transition temperature of 63K. Films pyrolyzed at 525 C and subsequently annealed at 780 C in a p(O 2 ) of 3.5 x 10 -4 atm contained YBCO phase predominantly in a-axis orientation. In the sol-gel route, yttrium-isopropoxide, barium metal, copper methoxide and 2-methoxyethanol were used as the starting reagents. Sol-gel YBCO films on SrTiO 3 substrates were epitaxial and c-axis oriented

  16. Development of an YBCO coil with SSTC conductors for high field application

    Science.gov (United States)

    Shi, Y.; Liu, H. J.; Liu, F.; Tan, Y. F.; Jin, H.; Yu, M.; Lei, L.; Guo, L.; Hong, Z. Y.

    2018-07-01

    With the continuous reduction of the production costs and improvement of the transport performance, YBCO coated conductor is the most promising candidate for the high field magnet application due to its high irreversibility field and strong mechanical properties. Presently a stable production capacity of the YBCO conductors has been achieved by Shanghai Superconducting Technology Co., Ltd (SSTC) in China. Therefore, the demand in high field application with YBCO conductors is growing in China. This paper describes the design, fabrication and preliminary experiment of a solenoid coil with YBCO conductors supplied by SSTC to validate the possibility of high field application. Four same double pancakes were manufactured and assembled for the YBCO coil where the outer diameter and height was 54.3 and 48 mm respectively to match the dimensional limitation of the 14 T background magnets. The critical current (Ic) of YBCO conductors was obtained by measuring as a function of the applied field perpendicular to the YBCO conductor surface which provides the necessary input parameters for preliminary performance evaluation of the coil. Finally the preliminary test and discussion at 77 and 4.2 K were carried out. The consistency of four double pancakes Ic was achieved. The measured results indicate that the fabrication technology of HTS coil is reliable which gives the conference for the in-field test in high field application. This YBCO coil is the first demonstration of the SSTC YBCO coated conductors.

  17. Terahertz detectors using hot-electrons in superconducting films

    Energy Technology Data Exchange (ETDEWEB)

    Semenov, A. [DLR, Inst. of Planetary Research, Berlin (Germany)

    2007-07-01

    Recently the terahertz gap has been recognized as a prospective spectral range for radioastronomy as well as for material and security studies. Implementation of terahertz technology in these fields requires further improvement of instruments and their major subcomponents. Physical phenomena associated with the local and homogeneous non-equilibrium electron sates in thin superconducting films offer numerous possibilities for the development of terahertz and infrared detectors. Depending on the nature of the resistive state and the operation regime, a variety of detector can be realized. They are e.g. direct bolometric or kinetic inductance detectors, heterodyne mixers or photon counters. Operation principles and physical limitations of these devices will be discussed. Two examples of the detector development made in cooperation between the German Aerospace Center, the University of Karlsruhe and PTB, Berlin will be presented. The energy resolving single-photon detector with an almost fundamentally limited energy resolution of 0.6 eV at 6.5 K for photons with wavelengths from 400 nm to 2500 nm and the heterodyne mixer quasioptically coupled to radiation in the frequency range from 0.8 THz to 5 THz and providing a noise temperature of less then ten times the quantum limit. The mixers will be implemented in the terahertz radar for security screening (TERASEC) and in the heterodyne receiver of the stratospheric observatory SOFIA. (orig.)

  18. Superconducting properties of In-Ge mixture films

    International Nuclear Information System (INIS)

    Gerber, A.; Deutscher, G.

    1987-01-01

    We report on measurements of the perpendicular H/sub c//sub perpendicular/ and parallel H/sub c//sub X/ upper critical fields of superconducting In-Ge mixture films in a wide range of In concentrations. The resistivities of the samples varied from about 10 μΩX, corresponding to high In concentration, up to about 1300 μΩ cm, corresponding to an In concentration close to the percolation threshold of the system. The critical temperatures of the samples in a zero external field have also been studied. For high metal concentrations the results have been analyzed and found to fit the predictions of the dirty limit for type-II superconductors. Near the threshold, however, where the normal-state resistivity goes to infinity, the critical fields saturate to a finite value. This result is in accordance with the prediction of percolation theory in the anomalous diffusion regime. As the threshold is approached the anisotropy ratio decreases to a constant value of 1.2 from its homogeneous type-II limit 1.69

  19. Characterization of Microstructure and Performance of YBa2Cu3O7−x Films Synthesized Through Sol–Gel Aqueous Precursors with DEA/TEA Addition

    DEFF Research Database (Denmark)

    Tang, Xiao; He, Dong; Zhao, Yichun

    2013-01-01

    YBa2Cu3O7−x (YBCO) superconducting thin films are synthesized through non-fluorine sol–gel aqueous processes. Diethanolamine (DEA) and triethonalamine (TEA), which have similar molecular structures but different complexation abilities and molecular weights, are separately used as chelating agents...

  20. Generation of coherent electromagnetic radiation by superconducting films at nitrogen temperatures

    CERN Document Server

    Lykov, A N

    2001-01-01

    One detected generation of coherent electromagnetic radiation by GdBa sub 2 Cu sub 3 O sub 7 sub - sub x superconducting films within 1-10 MHz range at temperature of liquid nitrogen boiling. This type generation is caused by synchronization realized due to the feedback of abrupt changes of the Abrikosov's vortices produced by the external low-frequency magnetic field. Possibility to reach more intensive radiation due to increase of the area of superconducting film, as well as, via increase of amplitude and of frequency of electromagnetic field exciting a vortex system in films is the most important advantage of the given technique of generation

  1. A study for designing YBCO power transformer

    International Nuclear Information System (INIS)

    Hayashi, H.; Okamoto, H.; Harimoto, T.; Imayoshi, T.; Tomioka, A.; Bouno, T.; Konno, M.; Iwakuma, M.

    2007-01-01

    It is highly expected that superconducting transformers, which are characterized by incombustibility, light weight, and compactness, will be used practically for equipment in substations and office buildings sited in urban areas. In recent years, remarkable improvements in the performance of YBaCuO (YBCO) tape wire have been seen. This kind of tape wire has the property that its critical current is large in a highly magnetic field; and, its use is expected to reduce AC loss by applying slit processing on the tape wire, contributing to future cost reductions. In addition, the development of efficient, economical cryogenic units is also expected. The authors have developed a conceptual design for a 66 kV/20 MVA power transformer using YBCO tape wires, or an YBCO power transformer. As a result, we were able to identify the transformer's optimal system structure including coil winding comprised of coils and tape wires; and, we confirmed that the devised transformer can made to be both compact and highly efficient

  2. Degradation of superconducting Nb/NbN films by atmospheric oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Henry, Michael David; Wolfley, Steven L.; Young, Travis Ryan; Monson, Todd; Pearce, Charles Joseph; Lewis, Rupert M.; Clark, Blythe; Brunke, Lyle Brent; Missert, Nancy A.

    2017-03-01

    Niobium and niobium nitride thin films are transitioning from fundamental research toward wafer scale manufacturing with technology drivers that include superconducting circuits and electronics, optical single photon detectors, logic, and memory. Successful microfabrication requires precise control over the properties of sputtered superconducting films, including oxidation. Previous work has demonstrated the mechanism in oxidation of Nb and how film structure could have deleterious effects upon the superconducting properties. This study provides an examination of atmospheric oxidation of NbN films. By examination of the room temperature sheet resistance of NbN bulk oxidation was identified and confirmed by secondary ion mass spectrometry. As a result, Meissner magnetic measurements confirmed the bulk oxidation not observed with simple cryogenic resistivity measurements.

  3. Deposition of superconducting (Cu, C)-Ba-O films by pulsed laser deposition at moderate temperature

    International Nuclear Information System (INIS)

    Yamamoto, Tetsuro; Kikunaga, Kazuya; Obara, Kozo; Terada, Norio; Kikuchi, Naoto; Tanaka, Yasumoto; Tokiwa, Kazuyasu; Watanabe, Tsuneo; Sundaresan, Athinarayanan; Shipra

    2007-01-01

    Superconducting (Cu, C)-Ba-O thin films have been epitaxially grown on (100) SrTiO 3 at a low growth temperature of 500-600 deg. C by pulsed laser deposition. The dependences of their crystallinity and transport properties on preparation conditions have been investigated in order to clarify the dominant parameters for carbon incorporation and the emergence of superconductivity. It has been revealed that the CO 3 content in the films increases with increasing both the parameters of partial pressure of CO 2 during film growth and those of growth rate and enhancement of superconducting properties. The present study has also revealed that the structural and superconducting properties of the (Cu, C)-Ba-O films are seriously deteriorated by the irradiation of energetic particles during deposition. Suppression of the radiation damage is another key for a high and uniform superconducting transition. By these optimizations, a superconducting onset temperature above 50 K and a zero-resistance temperature above 40 K have been realized

  4. Superconductivity

    International Nuclear Information System (INIS)

    Langone, J.

    1989-01-01

    This book explains the theoretical background of superconductivity. Includes discussion of electricity, material fabrication, maglev trains, the superconducting supercollider, and Japanese-US competition. The authors reports the latest discoveries

  5. Contribution of ion beam analysis methods to the development of 2nd generation high temperature superconducting (HTS) wires

    Energy Technology Data Exchange (ETDEWEB)

    Usov, Igor O [Los Alamos National Laboratory; Arendt, Paul N [Los Alamos National Laboratory; Stan, Liliana [Los Alamos National Laboratory; Holesinger, Terry G [Los Alamos National Laboratory; Foltyn, Steven R [Los Alamos National Laboratory; Depaula, Raymond F [Los Alamos National Laboratory

    2009-01-01

    One of the crucial steps in the second generation high temperature superconducting wire program was development of the buffer layer architecture. The architecture designed at the Superconductivity Technology Center at Los Alamos National Laboratory consists of several oxide layers wherein each layer plays a specific role, namely: nucleation layer, diffusion barrier, biaxially textured template, and an intermediate layer with a good match to the lattice parameter of superconducting Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7} (YBCO) compound. This report demonstrates how a wide range of ion beam analysis techniques (SIMS, RBS, channeling, PIXE, PIGE, NRA, ERD) was employed for analysis of each buffer layer and the YBCO films. These results assisted in understanding of a variety of physical processes occurring during the buffet layer fabrication and helped to optimize the buffer layer architecture as a whole.

  6. Superconductivity

    International Nuclear Information System (INIS)

    Onnes, H.K.

    1988-01-01

    The author traces the development of superconductivity from 1911 to 1986. Some of the areas he explores are the Meissner Effect, theoretical developments, experimental developments, engineering achievements, research in superconducting magnets, and research in superconducting electronics. The article also mentions applications shown to be technically feasible, but not yet commercialized. High-temperature superconductivity may provide enough leverage to bring these applications to the marketplace

  7. Characterization of superconducting thin films by infrared reflection

    International Nuclear Information System (INIS)

    Gervais, F.

    1988-01-01

    Infrared reflectivity spectroscopy is shown to be a powerful tool to characterize the new high-Tc oxide superconductors since it gives information about the superconducting gap, phonons, plasmon and possibly low-energy electronic excitations such as excitons, information relevant to understand the mechanism of superconductivity [fr

  8. A review of basic phenomena and techniques for sputter-deposition of high temperature superconducting films

    Energy Technology Data Exchange (ETDEWEB)

    Auciello, O. (Microelectronics Center of North Carolina, Research Triangle Park, NC (USA) North Carolina State Univ., Raleigh, NC (USA). Dept. of Materials Science and Engineering); Ameen, M.S.; Kingon, A.I.; Lichtenwalner, D.J. (North Carolina State Univ., Raleigh, NC (USA). Dept. of Materials Science and Engineering); Krauss, A.R. (Argonne National Lab., IL (USA))

    1990-01-01

    The processes involved in plasma and ion beam sputter-deposition of high temperature superconducting thin films are critically reviewed. Recent advances in the development of these techniques are discussed in relation to basic physical phenomena, specific to each technique, which must be understood before high quality films can be produced. Control of film composition is a major issue in sputter-deposition of multicomponent materials. Low temperature processing of films is a common goal for each technique, particularly in relation to integrating high temperature superconducting films with the current microelectronics technology. It has been understood for some time that for Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7} deposition, the most intensely studied high-{Tc} compound, incorporation of sufficient oxygen into the film during deposition is necessary to produce as-deposited superconducting films at relatively substrate temperatures. Recent results have shown that with the use of suitable buffer layers, high quality Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7} sputtered films can be obtained on Si substrates without the need for post-deposition anneal processing. This review is mainly focussed on issues related to sputter-deposition of Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7} thin films, although representative results concerning the bismuth and thallium based compounds are included. 143 refs., 11 figs.

  9. Superconductivity

    International Nuclear Information System (INIS)

    Andersen, N.H.; Mortensen, K.

    1988-12-01

    This report contains lecture notes of the basic lectures presented at the 1st Topsoee Summer School on Superconductivity held at Risoe National Laboratory, June 20-24, 1988. The following lecture notes are included: L.M. Falicov: 'Superconductivity: Phenomenology', A. Bohr and O. Ulfbeck: 'Quantal structure of superconductivity. Gauge angle', G. Aeppli: 'Muons, neutrons and superconductivity', N.F. Pedersen: 'The Josephson junction', C. Michel: 'Physicochemistry of high-T c superconductors', C. Laverick and J.K. Hulm: 'Manufacturing and application of superconducting wires', J. Clarke: 'SQUID concepts and systems'. (orig.) With 10 tabs., 128 figs., 219 refs

  10. High-frequency properties of superconducting Y-Ba-Cu-oxide thin films

    International Nuclear Information System (INIS)

    Ramakrishnan, E.S.; Su, M.; Howng, W.

    1992-01-01

    rf and microwave properties of superconducting YBa 2 Cu 3 O 7-x thin films were measured and analyzed using a coplanar resonator structure. The films were developed by sequential electron-beam evaporation of the metals followed by postanneal processing. dc properties of the films were obtained from resistance-temperature and current-voltage measurements to evaluate the transition temperature and current densities. High-frequency properties were measured from 70 to 10 K and in the frequency range 1--3 GHz to determine the film characteristics as compared to pure copper films on the same substrates

  11. Superconductivity

    International Nuclear Information System (INIS)

    Palmieri, V.

    1990-01-01

    This paper reports on superconductivity the absence of electrical resistance has always fascinated the mind of researchers with a promise of applications unachievable by conventional technologies. Since its discovery superconductivity has been posing many questions and challenges to solid state physics, quantum mechanics, chemistry and material science. Simulations arrived to superconductivity from particle physics, astrophysic, electronics, electrical engineering and so on. In seventy-five years the original promises of superconductivity were going to become reality: a microscopical theory gave to superconductivity the cloth of the science and the level of technological advances was getting higher and higher. High field superconducting magnets became commercially available, superconducting electronic devices were invented, high field accelerating gradients were obtained in superconductive cavities and superconducting particle detectors were under study. Other improvements came in a quiet progression when a tornado brought a revolution in the field: new materials had been discovered and superconductivity, from being a phenomenon relegated to the liquid Helium temperatures, became achievable over the liquid Nitrogen temperature. All the physics and the technological implications under superconductivity have to be considered ab initio

  12. Superconductivity

    CERN Document Server

    Thomas, D B

    1974-01-01

    A short general review is presented of the progress made in applied superconductivity as a result of work performed in connection with the high-energy physics program in Europe. The phenomenon of superconductivity and properties of superconductors of Types I and II are outlined. The main body of the paper deals with the development of niobium-titanium superconducting magnets and of radio-frequency superconducting cavities and accelerating structures. Examples of applications in and for high-energy physics experiments are given, including the large superconducting magnet for the Big European Bubble Chamber, prototype synchrotron magnets for the Super Proton Synchrotron, superconducting d.c. beam line magnets, and superconducting RF cavities for use in various laboratories. (0 refs).

  13. The magnetoresistance of YBCO/BZO composite superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Malik, Bilal A. [Department of Physics, University of Kashmir, Srinagar- 190006 (India); Asokan, K. [Materials Science Division, Inter University Accelerator Centre, New Delhi -110067 (India); Ganesan, V; Singh, Durgesh [UGC-DAE Consortium for Scientific Research, Khandwa Road, Indore (MP) 452 001 (India); Malik, Manzoor A., E-mail: mmalik@kashmiruniversity.ac.in [Department of Physics, University of Kashmir, Srinagar- 190006 (India)

    2016-12-15

    Highlights: • Limited addition of BZO in YBCO shows low resistive tailing behavior. • Limited addition of BZO in YBCO increases the activation energy of flux lines. • Vortex glass transition temperature increases with the limited addition of BZO. • Significant enhancement of H{sub C2}(0) is observed up to 4% BZO addition. - Abstract: We study the effect of addition of BaZrO{sub 3} (BZO) on normal and superconducting state of YBa{sub 2}Cu{sub 3}O{sub 7-δ} (YBCO). We find that in general both room temperature and residual resistivity increase with the addition of BZO except at low concentration of BZO. The temperature dependence of resistivity in presence of magnetic field also shows less resistivity broadening in composites containing low concentration of BZO below transition temperature (T{sub C}). The zero temperature upper critical field (H{sub c2}(0)), estimated by using Werthamer, Helfand and Hohenberg theory and Ginzburg Landau theory, shows an increase by the finite addition of BZO in YBCO. Further, the activation energy (U{sub 0}) determined from Arrhenius plots and vortex glass transition temperature (T{sub g}) also increase with the limited addition of BZO. Such an enhancement in H{sub c2}(0), U{sub o} and T{sub g} has been attributed to the increase in grain connectivity of YBCO . We conclude that the limited addition of BZO in YBCO significantly improves its superconducting performance in magnetic environment.

  14. Examination of a microwave sensing system using superconducting devices

    International Nuclear Information System (INIS)

    Sekiya, N.; Mukaida, M.; Saito, A.; Hirano, S.; Oshima, S.

    2005-01-01

    We have designed and fabricated a microwave sensing system integrated with superconducting devices which can detect motion for crime prevention and security purposes. The system consists of a transmitting antenna, a receiving antenna, a power divider as a directional coupler, and a mixer. The antennas and the directional coupler were fabricated using 50-nm thick YBa 2 Cu 3 O 7-δ (YBCO) thin films. A superconducting antenna with a resonant frequency of 10.525 GHz and a superconducting directional coupler were designed and fabricated for the system. A Schottky barrier diode was used as a mixer. These devices were integrated and their operation as a sensor was examined. Comparisons of the output voltage of the IF signal amplifier showed that the superconducting integrated sensor system was superior to the normal conductor sensor

  15. Effect of point disorder on superconducting properties of ultrathin epitaxial NbN films

    International Nuclear Information System (INIS)

    Jesudasan, John; Bagwe, Vivas; Mondal, Mintu; Chand, Madhavi; Kamlapure, Anand; Pai, S.P.; Raychaudhuri, Pratap; Mishra, Archana

    2009-01-01

    We synthesized homogeneously disordered epitaxial NbN films on MgO(100) substrates using reactive dc magnetron sputtering. The disorder of the films is characterized by the Loffe-Regel parameter k F I. The superconducting properties are studied through transport, ac-susceptibility measurements and electron tunneling. The superconducting transition temperature is studied as a function of thickness for films of different disorder. In the case of the less disordered film, there is a smooth decrease in T c with decreasing thickness but for the more disordered film, the T c shows a sharp decrease to zero at a threshold thickness. The superconducting energy gap is studied via planar tunnel junctions. It is found that for the less disordered films, the temperature dependence of the gap follows the BCS variation but for the more disordered ones, there is a significant deviation from the BCS curve, and the gap remains finite at T c indicating that the superconducting transition is either governed by phase fluctuations or a first order phase transition. (author)

  16. Ultrathin NbN Films for Superconducting Single-Photon Detectors

    International Nuclear Information System (INIS)

    Slysz, W.; Guziewicz, M.; Borysiewicz, M.

    2011-01-01

    We present our research on fabrication and structural and transport characterization of ultrathin superconducting NbN layers deposited on both single-crystal Al 2 O 3 and Si wafers, and SiO 2 and Si 3 N 4 buffer layers grown directly on Si wafers. The thicknesses of our films varied from 6 nm to 50 nm and they were grown using reactive RF magnetron sputtering on substrates maintained at the temperature 850 o C. We have performed extensive morphology characterization of our films using the X-ray diffraction method and atomic force microscopy, and related the results to the type of the substrate used for the film deposition. Our transport measurements showed that even the thinnest, 6 nm thick NbN films had the superconducting critical temperature of 10-12 K, which was increased to 14 K for thicker films. (author)

  17. Misfit dislocations and phase transformations in high-T sub c superconducting films

    CERN Document Server

    Gutkin, M Y

    2002-01-01

    A theoretical model is suggested that describes the effects of misfit stresses on defect structures, phase content and critical transition temperature T sub c in high-T sub c superconducting films. The focus is placed on the exemplary case of YBaCuO films deposited onto LaSrAlO sub 4 substrates. It is theoretically revealed here that misfit stresses are capable of inducing phase transformations controlled by the generation of misfit dislocations in growing cuprate films. These transformations, in the framework of the suggested model, account for experimental data on the influence of the film thickness on phase content and critical temperature T sub c of superconducting cuprate films, reported in the literature. The potential role of stress-assisted phase transformations in suppression of critical current density across grain boundaries in high-T sub c superconductors is briefly discussed.

  18. AC over-current test results of YBCO conductor for YBCO power transformer with fault current limiting function

    International Nuclear Information System (INIS)

    Tomioka, A.; Otonari, T.; Ogata, T.; Iwakuma, M.; Okamoto, H.; Hayashi, H.; Iijima, Y.; Saito, T.; Gosho, Y.; Tanabe, K.; Izumi, T.; Shiohara, Y.

    2011-01-01

    The single-layer coils with a diameter of 250 mm and 12 turns were manufactured with YBCO tapes with a CuNi- or Cu-Tape. The AC over-current tests were carried out in subcooled liquid nitrogen at 66 K and 74 K to develop power transformers with current limiting function. The AC over-current was two to seven times larger than the I c of conductor and it was reduced to the same level of I c . The I c of model coils did not degrade. The test results showed the possibility of YBCO superconducting transformers with current limiting function. We are developing elemental technology for 66 kV/6.9 kV 20 MVA-class YBCO power transformer. The YBCO transformer is considered to have a possibility to stabilize the power system by improving function of fault current limiting. Current limiting behavior functions over critical current flows. There is a possibility that superconducting characteristic may be damaged due to increase in temperature of YBCO tapes. Therefore, we have taken a measure to combine YBCO tape with CuNi tape or Cu Tape. We manufactured model coils using these conductors and conducted the AC over-current tests. The test current was two to seven times larger than the I c of conductor and it was damped with time from its maximum value according to the generation of conductor resistance. We verified the effectiveness of current limiting characteristics. In these tests, the I c of model coil did not degrade. We consider this conductor to be able to withstand AC over-current with the function of current limiting.

  19. Infrared refractive index of thin YBa2Cu3O7 superconducting films

    International Nuclear Information System (INIS)

    Zhang, Z.M.; Choi, B.I.; Le, T.A.; Flik, M.I.; Siegal, M.P.; Phillips, J.M.

    1992-01-01

    This work investigates whether thin-film optics with a constant refractive index can be applied to high-T c superconducting thin films. The reflectance and transmittance of YBa 2 Cu 3 O 7 films on LaAlO 3 substrates are measured using a Fourier-transform infrared spectrometer at wavelengths from 1 to 100 μm at room temperature. The reflectance of these superconducting films at 10K in the wavelength region from 2.5 to 25 μm is measured using a cryogenic reflectance accessory. The film thickness varies from 10 to 200 nm. By modeling the frequency-dependent complex conductivity in the normal and superconducting states and applying electromagnetic-wave theory, the complex refractive index of YBa 2 Cu 3 O 7 films is obtained with a fitting technique. It is found that a thickness-independent refractive index can be applied even to a 25nm film, and average values of the spectral refractive index for film thicknesses between 25 and 200 nm are recommended for engineering applications

  20. A novel selenization technique for fabrication of superconducting FeSex thin film

    International Nuclear Information System (INIS)

    Chai Qinglin; Tu Hailing; Hua Zhiqiang; Wang Lei; Qu Fei

    2011-01-01

    A novel selenization technique was applied to prepare superconducting FeSe x films with pre-set FeS films. The combination of reactive sputtering deposition with elemental diffusion technique would extend to prepare films of other iron-based superconductors. The results of transport measurement got close or greater than that of previous reports. T c,onset and T c,0 got to 10.2 K and 4 K respectively. We believe that increase of the content of Fe 7 Se 8 could not only reduce T c but also slow down the decline of resistivity. A combinative method with reactive sputtering deposition and selenization technique was applied to prepare superconducting FeSe x films on LaAlO 3 substrates successfully. The influence of selenizing temperature on film components was studied. FeSe 0.96 and FeSe films had similar and good performances in transport measurement but little difference in magnetic property. The critical onset temperature got to 11.2 K and T c,0 got to 4 K approximately. X-ray diffraction, energy dispersive spectroscopy and scanning electron microscopy were used to analyze the ratio of constituents and morphology of several selenized films. FeSe x film had a porous structure on surface and no well preferred orientation, which were confirmed to have little influence on superconducting properties.

  1. Bi-Sr-Ca-Cu-O superconducting thin films: theory and experiment

    Energy Technology Data Exchange (ETDEWEB)

    Yavuz, M [Department of Mechanical Engineering and Mechatronics Engineering Program, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Boybay, M S [Department of Mechanical Engineering and Mechatronics Engineering Program, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Elbuken, C [Department of Mechanical Engineering and Mechatronics Engineering Program, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Andrews, M J [Los Alamos National Lab, PO Box 1663, Mail Stop B 296, Los Alamos, NM 87545 (United States); Hu, C R [Department of Physics, Texas A and M University, College Station, Texas 77843 (United States); Ross, J H [Department of Physics, Texas A and M University, College Station, Texas 77843 (United States)

    2006-06-01

    The interest of this paper centers on fabrication and characterization and modeling of vortices in high temperature superconducting thin films. As a first step, the magnetic vertices of the superconducting matrix were modeled. As a second, Bi-Sr-Ca-Cu-O thin films were grown using Pulsed Laser Ablation (PLD) on single crystal MgO substrates as magnetic templates for the potential use for Nano and Microelectronic circuits, and were characterized by x-ray diffraction, electron, and atomic force microscopy. The third step (future work) will be observation and pinning of these vortices using Bitter decoration.

  2. Superconductivity applications for infrared and microwave devices II; Proceedings of the Meeting, Orlando, FL, Apr. 4, 5, 1991

    Science.gov (United States)

    Heinen, Vernon O.; Bhasin, Kul B.

    Topics discussed include thin-film technology, microwave transmission lines and resonators, microwave devices and circuits, infrared detectors and bolometers, and superconducting junctions. Papers are presented on possible enhancement in bolometric response using free-standing film of YBa2Cu3O(x), aging and surface instability in high-Tc superconductors, epitaxial Tl2Ba2CaCu2O8 thin films on LaAlO3 and their microwave device properties, the performance of stripline resonators using sputtered YBCO films, and a coplanar waveguide microwave filter of YBa2Cu3O7. Attention is also given to the performance characteristics of Y-Ba-Cu-O microwave superconducting detectors, high-Tc bolometer developments for planetary missions, infrared detectors from YBaCuO thin films, high-temperature superconductor junction technology, and submillimeter receiver components using superconducting tunnel junctions. (For individual items see A93-27244 to A93-27248)

  3. Superconductivity

    International Nuclear Information System (INIS)

    Kakani, S.L.; Kakani, Shubhra

    2007-01-01

    The monograph provides readable introduction to the basics of superconductivity for beginners and experimentalists. For theorists, the monograph provides nice and brief description of the broad spectrum of experimental properties, theoretical concepts with all details, which theorists should learn, and provides a sound basis for students interested in studying superconducting theory at the microscopic level. Special chapter on the theory of high-temperature superconductivity in cuprates is devoted

  4. YBCO hot-electron bolometers dedicated to THz detection and imaging: Embedding issues

    International Nuclear Information System (INIS)

    Aurino, M; Tuerer, I; Martinez, A; Gensbittel, A; Degardin, A F; Kreisler, A J

    2010-01-01

    High-T c hot-electron bolometers (HEB) are an interesting alternative to other superconducting heterodyne mixers in the terahertz frequency range because of low-cost cooling investment, ultra-wide instantaneous bandwidth and low intrinsic noise level, even at 80 K. A technological process to fabricate stacked yttrium-based (YBCO) / praseodymium-based (PBCO) ultra-thin films (in the 15 to 40 nm thickness range) etched to form 0.5 μm x 0.5 μm constrictions, elaborated on (100) MgO substrates, has been previously described. Ageing effects were also considered, with the consequence of increased electrical resistance, significant degradation of the regular THz response and no HEB mixing action. Electron and UV lithography steps are revisited here to realize HEB mixers based on nano-bridges covered by a log-periodic planar gold antenna, dedicated to the 1 to 7 THz range. Several measures have been attempted to reduce the conversion losses, mainly by considering the embedding issues related to the YBCO nano-bridge impedance matching to the antenna and the design of optimized intermediate frequency circuitry. Antenna simulations were performed and validated through experiments on scaled models at GHz frequencies. Electromagnetic coupling to the incoming radiation was also studied, including crosstalk between neighbour antennas forming a linear imaging array.

  5. Secondary phase formation in YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} thin films and YBa{sub 2}Cu{sub 3}O{sub 7-{delta}}/SrTiO{sub 3} superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, C.N.L.

    1996-06-01

    Studies of YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (YBCO) thin films and YBCO/STO superlattices has been performed. The dc magnetron sputtered YBCO single layer investigation concerned the dependence of the secondary phase formation and superconducting transport properties on sputtering target and ambient gas composition. YBCO/STO superlattices, grown by dc and rf magnetron sputtering, respectively, were analyzed with respect to microstructure and formation of secondary phases. The main characterization techniques used in this study have been x-ray diffraction to identify phases and to obtain orientational relationships, scanning electron microscopy to study surface morphology, transmission electron microscopy for microstructural characterization, and energy-dispersive x-ray spectroscopy for chemical characterization. With the aim to reduce or avoid the formation of copper-rich surface particles and still maintain satisfactory superconducting transport properties, YBCO films were deposited using copper-poor or yttrium-rich sputtering targets in an Ar:O{sub 2} or Ar:O{sub 2}:N{sub 2}O sputtering gas mixture. It was found that the use of yttrium-rich targets and N{sub 2}O in the sputtering gas is a reliable way to achieve smooth films without surface particles and with satisfactory superconducting properties, while the use of copper-poor targets and N{sub 2}O deteriorates those properties. Based on the previous results, YBCO/STO superlattices were grown using yttrium-rich YBCO targets and stoichiometric STO targets, respectively, in a Ar:O{sub 2}:N{sub 2}O sputtering gas mixture. The superlattices were found to have sharp interfaces and no indications of interface reactions were detected. 61 refs, 18 figs, 3 tabs

  6. Multilayered structures of (RE = rare earth)Ba2Cu3Ox films: an approach for the growth of superior quality large-area superconducting films on sapphire substrates

    International Nuclear Information System (INIS)

    Develos-Bagarinao, K; Yamasaki, H; Ohki, K; Nakagawa, Y

    2007-01-01

    Relatively thick REBa 2 Cu 3 O 7-δ (RE = rare earth) films (thickness ∼400-600 nm) with significantly improved surface morphology and critical current properties using a multilayered structure which alternates main layers of YBa 2 Cu 3 O 7-δ (YBCO) with intermediate DyBa 2 Cu 3 O 7-δ (DyBCO) layers on CeO 2 -buffered sapphire substrates were investigated. The DyBCO layer, which has a close lattice matching with YBCO, functions as a good starting template for the growth of high-quality YBCO layers. Critical current density (J c ) drastically increased up to a factor of 2 for YBCO/DyBCO multilayer films, compared to YBCO monolayer films in both the self-field and applied magnetic field. The significant improvement in J c is attributed to the improvement of surface smoothness and enhanced flux pinning properties as revealed by the magnetic-field angular dependence of J c . (rapid communication)

  7. Superconducting TlCa2Ba2Cu3O9 thick films

    International Nuclear Information System (INIS)

    1994-01-01

    GE Corporate Research and Development's (GE-CRD) program to develop the two-zone silver addition (TZSA) process for fabricating superconducting films of TlCa 2 Ba 2 Cu 3 O 9 has activities in the areas of (1) precursor preparation, (2) the thallium oxide vapor process, (3) the effects of post-synthesis annealing ambient and temperature on superconducting properties, (4) the influence of film stoichiometry and composition on superconducting properties, (5) microstructure and film growth mechanism, (6) the preparation of thicker films, (7) the fabrication of films on flexible substrates, and (8) process scale-up. As part of its effort under the ANL Pilot Center Agreement, GE-CRD has supplied to ANL a complete two-zone furnace, has provided consultation on its use and on the planning of experiments, has processed ANL samples in GE's furnaces to help define optimum process conditions, and has provided precursor and finished films as requested. These contributions are described more fully in the descriptions of the work performed at ANL presented elsewhere in this report. Under the Pilot Center Agreement work at GE-CRD has been directed toward the optimization of the TZSA process with emphasis on (A) process improvement, (B) effects of silver content on film properties, (C) the relationship between microstructure and J c , and (D) toward the assessment of the compatibility of silver substrates with the process chemistry

  8. Preparation and characterization of high-Tc superconducting thin films with high critical current densities

    International Nuclear Information System (INIS)

    Vase, P.

    1991-08-01

    The project was carried out in relation to possible cable and electronics applications of high-T c materials. Laser ablation was used as the deposition technique because of its stoichiometry conservation. Films were made in the YBa 2 Cu 3 O 7 compound due to its relatively simple stoichiometry compared to other High-T c compounds. Much attention was paid to the critical current density. A very high critical current density was reached. By using texture analysis by X-ray diffraction, it was found that films with high critical current densities were epitaxial, while films with low critical current densities contained several crystalline orientations. Four techniques for patterning the films were used - photo lithography and wet etch, laser ablation lithography, laser writing and electron beam lithography and ion milling. Sub-micron patterning has been demonstrated without degradation of the superconducting properties. The achieved patterning resolution is sufficient for preparation of many superconducting components. (AB)

  9. Niobium thin film deposition studies on copper surfaces for superconducting radio frequency cavity applications

    Energy Technology Data Exchange (ETDEWEB)

    W. M. Roach, D. B. Beringer, J. R. Skuza, W. A. Oliver, C. Clavero, C. E. Reece, R. A. Lukaszew

    2012-06-01

    Thin film coatings have the potential to increase both the thermal efficiency and accelerating gradient in superconducting radio frequency accelerator cavities. However, before this potential can be realized, systematic studies on structure-property correlations in these thin films need to be carried out since the reduced geometry, combined with specific growth parameters, can modify the physical properties of the materials when compared to their bulk form. Here, we present our systematic studies of Nb thin films deposited onto Cu surfaces to clarify possible reasons for the limited success that this process exhibited in previous attempts. We compare these films with Nb grown on other surfaces. In particular, we study the crystal structure and surface morphology and their effect on superconducting properties, such as critical temperature and lower critical field. We found that higher deposition temperature leads to a sharper critical temperature transition, but also to increased roughness indicating that there are competing mechanisms that must be considered for further optimization.

  10. Niobium thin film deposition studies on copper surfaces for superconducting radio frequency cavity applications

    International Nuclear Information System (INIS)

    Roach, W.M.; Beringer, D.B.; Skuza, J.R.; Oliver, W.A.; Clavero, C.; Reece, C.E.; Lukaszew, R.A.

    2012-01-01

    Thin film coatings have the potential to increase both the thermal efficiency and accelerating gradient in superconducting radio frequency accelerator cavities. However, before this potential can be realized, systematic studies on structure-property correlations in these thin films need to be carried out since the reduced geometry, combined with specific growth parameters, can modify the physical properties of the materials when compared to their bulk form. Here, we present our systematic studies of Nb thin films deposited onto Cu surfaces to clarify possible reasons for the limited success that this process exhibited in previous attempts. We compare these films with Nb grown on other surfaces. In particular, we study the crystal structure and surface morphology and their effect on superconducting properties, such as critical temperature and lower critical field. We found that higher deposition temperature leads to a sharper critical temperature transition, but also to increased roughness indicating that there are competing mechanisms that must be considered for further optimization.

  11. Superconductivity

    International Nuclear Information System (INIS)

    Caruana, C.M.

    1988-01-01

    Despite reports of new, high-temperature superconductive materials almost every day, participants at the First Congress on Superconductivity do not anticipate commercial applications with these materials soon. What many do envision is the discovery of superconducting materials that can function at much warmer, perhaps even room temperatures. Others hope superconductivity will usher in a new age of technology as semiconductors and transistors did. This article reviews what the speakers had to say at the four-day congress held in Houston last February. Several speakers voiced concern that the Reagan administration's apparent lack of interest in funding superconductivity research while other countries, notably Japan, continue to pour money into research and development could hamper America's international competitiveness

  12. Niobium thin film deposition studies on copper surfaces for superconducting radio frequency cavity applications

    OpenAIRE

    W. M. Roach; D. B. Beringer; J. R. Skuza; W. A. Oliver; C. Clavero; C. E. Reece; R. A. Lukaszew

    2012-01-01

    Thin film coatings have the potential to increase both the thermal efficiency and accelerating gradient in superconducting radio frequency accelerator cavities. However, before this potential can be realized, systematic studies on structure-property correlations in these thin films need to be carried out since the reduced geometry, combined with specific growth parameters, can modify the physical properties of the materials when compared to their bulk form. Here, we present our systematic stu...

  13. Direct Observation of High-Temperature Superconductivity in One-Unit-Cell FeSe Films

    International Nuclear Information System (INIS)

    Zhang Wen-Hao; Zhang Jin-Song; Li Fang-Sen; Guo Ming-Hua; Ding Hao; Tang Chen-Jia; Wang Qing-Yan; He Ke; Ji Shuai-Hua; Chen Xi; Sun Yi; Zhao Yan-Fei; Xing Ying; Wang Hui-Chao; Zhang Hui-Min; Peng Jun-Ping; Li Zhi; Wang Meng; Fujita Takeshi; Hirata Akihiko

    2014-01-01

    We prepared one-unit-cell (1-UC) thick FeSe films on insulating SrTiO 3 substrates with non-superconducting FeTe protection layers by molecular beam epitaxy for ex situ studies. By direct transport and magnetic measurements, we provide definitive evidence for high temperature superconductivity in the 1-UC FeSe films with an onset T C above 40 K and an extremely large critical current density J C ∼1.7×10 6 A/cm 2 at 2 K, which are much higher than T C ∼8 K and J C ∼10 4 A/cm 2 for bulk FeSe, respectively. Our work may pave the way to enhancing and tailoring superconductivity by interface engineering. (express letter)

  14. Superconducting thin films of Bi-Sr-Ca-Cu-O by laser ablation

    Science.gov (United States)

    Bedekar, M. M.; Safari, A.; Wilber, W.

    1992-11-01

    Superconducting thin films of Bi-Sr-Ca-Cu-O have been deposited by KrF excimer laser ablation. The best in situ films showed a Tc onset of 110 K and a Tc(0) of 76 K. A study of the laser plume revealed the presence of two distinct regimes. The forward directed component increased with fluence and the film composition was stoichiometric in this region. This is in agreement with the results on the 123 system by Venkatesan et al. [1]. The film properties were found to be critically dependent on the substrate temperature and temperatures close to melting gave rise to 2212 and 2223 phases. At lower temperatures, 2201 and amorphous phases were obtained. The film morphology and superconducting properties were a function of the target to substrate distance and the oxygen pressure during deposition and cooling. An increase in the target to substrate distance led to a deterioration of the properties due to the energy consideration for the formation of 2212 and 2223 phases. The best films were obtained using cooling pressures of 700 Torr. The microwave surface resistance of the films measured at 35 GHz dropped below that of copper at 30 K. Film growth was studied using X-ray diffraction and STM/AFM. This work is a discussion of the role of the different variables on the film properties.

  15. Development of Strontium Titanate Thin films on Technical Substrates for Superconducting Coated Conductors

    DEFF Research Database (Denmark)

    Pallewatta, Pallewatta G A P; Yue, Zhao; Grivel, Jean-Claude

    2012-01-01

    SrTiO3 is a widely studied perovskite material due to its advantages as a template for high temperature superconducting tapes. Heteroepitaxial SrTiO3 thin films were deposited on Ni/W tapes using dip-coating in a precursor solution followed by drying and annealing under reducing conditions. Nearl...

  16. Vortex pinning in superconducting Nb thin films deposited on nanoporous alumina templates

    DEFF Research Database (Denmark)

    Vinckx, W.; Vanacken, J.; Moshchalkov, V.V.

    2006-01-01

    We present a study of magnetization and transport properties of superconducting Nb thin films deposited on nanoporous aluminium oxide templates. Periodic oscillations in the critical temperature vs. field, matching effects in fields up to 700 mT and strongly enhanced critical currents were observed...

  17. Electric field dependence of excess electrical conductivity below transition temperature in thin superconducting lead films

    Energy Technology Data Exchange (ETDEWEB)

    Ashwini Kumar, P K; Duggal, V P [Delhi Univ. (India). Dept. of Physics and Astrophysics

    1976-01-26

    Results of measurements of the electric field dependence of the excess electrical conductivity are reported in thin superconducting lead films below the transition temperature. It is observed that the normal state sheet resistance has some effect on the nonlinearity but the theory of Yamaji still fits well to the experimental data.

  18. Superconductivity in volumetric and film ceramics Bi-Sr-Ca-Cu-O

    International Nuclear Information System (INIS)

    Sukhanov, A.A.; Ozmanyan, Kh.R.; Sandomirskij, B.B.

    1988-01-01

    A superconducting transition with T c0 =82-95 K and T c (R=0)=82-72 K was observed in volumetric and film Bi(Sr 1-x Ca x ) 2 Cu 3 O y samples obtained by solid-phase reaction. Temperature dependences of resistance critical current and magnetic susceptibility are measured

  19. Superconductivity in Bi-Sr-Ca-Cu-O bulk and film ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Sukhanov, A A; Ozmanian, KH R; Sandomirskii, B B

    1988-07-01

    A superconducting transition with Tc0 = 82-95 K and Tc(R = 0) = 82-72 K was observed in Bi(Sr/1-x/Ca/x/)2Cu3O(y) bulk and film specimens obtained via a solid-phase reaction. Temperature dependences of the resistance, critical current, and magnetic susceptibility were measured.

  20. Superconductivity effects near metal-insulator transition in granular idnium films

    International Nuclear Information System (INIS)

    Belevtsev, B.I.; Komnik, Yu.F.; Fomin, A.V.

    1986-01-01

    The influence of granules superconductivity on the electric properties of granular indium films is investigated under the conditions of partial or full granular localization of electrons. At temperatures below 5 K a minimum of electric resistance and negative magnetoresistance are revealed which are attributed to the competition of hopping conductivity and Josephson intergranular tunneling of electrons

  1. Buffer layers for REBCO films for use in superconducting devices

    Science.gov (United States)

    Goyal, Amit; Wee, Sung-Hun

    2014-06-10

    A superconducting article includes a substrate having a biaxially textured surface. A biaxially textured buffer layer, which can be a cap layer, is supported by the substrate. The buffer layer includes a double perovskite of the formula A.sub.2B'B''O.sub.6, where A is rare earth or alkaline earth metal and B' and B'' are different transition metal cations. A biaxially textured superconductor layer is deposited so as to be supported by the buffer layer. A method of making a superconducting article is also disclosed.

  2. Evolution of superconducting properties with disorder in epitaxial NbN films

    International Nuclear Information System (INIS)

    Chockalingam, S P; Chand, Madhavi; Jesudasan, John; Raychaudhuri, Pratap; Tripathi, Vikram

    2009-01-01

    NbN is a conventional BCS superconductor in which disorder can be tuned from moderately clean limit to dirty limit without affecting its epitaxial nature. We studied the superconducting properties of epitaxial NbN films of different disorder characterized by k F l ranging from 8.77 to 2.56 through the transport measurements. Using reactive magnetron sputtering NbN films of different disorder are deposited by varying the sputtering power and amount of N 2 in Ar:N 2 mixture of sputtering gas. The disorder parameter k F l is obtained from the carrier density (n) and the resistivity (ρ) of the films. NbN films with higher disorder have lower transition temperature (T c ) and larger resistivity which decreases with decreasing disorder. The carrier density determined from Hall measurements show that highly disordered films have lower carrier density and vice versa. Our studies show that NbN is a good system to investigate the effects of disorder on superconductivity where the superconducting properties evolve with the disorder in thin films.

  3. Thermoelectric power of the Ni and Cd substituted YBCO system

    International Nuclear Information System (INIS)

    Mukherjee, C.D.; Ranganathan, R.; Raychaudhuri, A.K.; Chatterjee, N.

    1989-01-01

    The thermoelectric power behaviour in the range between 250 K and the superconducting transition temperature T c of YBa 2 Cu 3-x A x O 7-y (where A = Ni or Cd and x = 0.2 and 0.4) samples has been examined. The normalized resistance and thermopower of substituted samples as functions of temperature are plotted and discussed. It was concluded that nickel has a slight positive role in causing overall thermopower generation in the YBCO system

  4. Applications of YBCO melt textured bulks in Maglev technology

    International Nuclear Information System (INIS)

    Zhao, Y.; Wang, J.S.; Wang, S.Y.; Ren, Z.Y.; Song, H.H.; Wang, X.R.; Cheng, C.H.

    2004-01-01

    In this paper we report the present status and progress of HTS Maglev project undertaken at the Southwest Jiaotong University. The efforts and results towards solving the material-related issues in HTS Maglev system are emphasized, including the levitation and guidance forces, the magnetic and thermal stabilities related to the ac loss of YBCO superconducting material during a high speed movement, and the low stiffness of HTS Maglev system

  5. Stationary states and dynamics of superconducting thin films

    DEFF Research Database (Denmark)

    Ögren, Magnus; Sørensen, Mads Peter; Pedersen, Niels Falsig

    can handle complex geometries also in a three-dimensional superconducting structure. To include external currents in our modelling we discuss the role of the boundary conditions for the external magnetic field [4]. Finally we show results for the pinning of vortices with controlled impurities....

  6. Superconductivity

    CERN Document Server

    Ketterson, John B

    2008-01-01

    Conceived as the definitive reference in a classic and important field of modern physics, this extensive and comprehensive handbook systematically reviews the basic physics, theory and recent advances in the field of superconductivity. Leading researchers, including Nobel laureates, describe the state-of-the-art in conventional and unconventional superconductors at a particularly opportune time, as new experimental techniques and field-theoretical methods have emerged. In addition to full-coverage of novel materials and underlying mechanisms, the handbook reflects continued intense research into electron-phone based superconductivity. Considerable attention is devoted to high-Tc superconductivity, novel superconductivity, including triplet pairing in the ruthenates, novel superconductors, such as heavy-Fermion metals and organic materials, and also granular superconductors. What’s more, several contributions address superconductors with impurities and nanostructured superconductors. Important new results on...

  7. Response of fractal penetration of magnetic flux to disorder landscape in superconducting films

    Science.gov (United States)

    Ye, Zuxin; Li, Qiang; Si, W. D.; Suenaga, M.; Solovyov, V. F.; Johnson, P. D.

    2005-10-01

    Magnetic flux front and induction contours in superconducting YBa2Cu3O7-δ films with defect size stilde ξ (superconducting coherence length) and s≫ξ are studied by magneto-optical imaging. Robust self-affine spatial correlation was observed using scaling analysis in the small pinning disorder-dominated ( stilde ξ) films. The roughness exponent α was determined to be ˜0.66 , independent of numbers of defects (or the film thickness). When the disorder landscape also included a distribution of large defects (s≫ξ) , the flux front and induction contours exhibited self-similarity, with a fractal dimension D determined to be ˜1.33 using the box-counting method. The remarkably different flux penetration patterns were shown to be the manifestation of self-organized criticality at different length scales.

  8. Molecular-Beam Epitaxially Grown MgB2 Thin Films and Superconducting Tunnel Junctions

    Directory of Open Access Journals (Sweden)

    Jean-Baptiste Laloë

    2011-01-01

    Full Text Available Since the discovery of its superconducting properties in 2001, magnesium diboride has generated terrific scientific and engineering research interest around the world. With a of 39 K and two superconducting gaps, MgB2 has great promise from the fundamental point of view, as well as immediate applications. Several techniques for thin film deposition and heterojunction formation have been established, each with its own advantages and drawbacks. Here, we will present a brief overview of research based on MgB2 thin films grown by molecular beam epitaxy coevaporation of Mg and B. The films are smooth and highly crystalline, and the technique allows for virtually any heterostructure to be formed, including all-MgB2 tunnel junctions. Such devices have been characterized, with both quasiparticle and Josephson tunneling reported. MgB2 remains a material of great potential for a multitude of further characterization and exploration research projects and applications.

  9. Structural and superconducting properties of sputter-deposited niobium films for applications in RF accelerating cavities

    CERN Document Server

    Peck, M A

    2000-01-01

    The present work presents the results of a systematic study of superconducting and structural properties of niobium films sputter deposited onto the inner walls of radiofrequency copper resonators. The measured superconducting quantities include the surface resistance, the critical temperature, the penetration depth and the upper and lower critical fields. In addition to films grown with different discharge gases (Xe, Kr, Ar, Ne and Ar-Ne mixtures) and to films grown on substrates prepared under different conditions, the study also includes massive niobium cavities. The surface resistance is analysed in terms of its dependence on the temperature and on the rf field amplitude and, when possible, compared to theoretical predictions. In general, good agreement with BCS theory is observed. All experimental results are presented in the form of a simple, but adequate parameterisation. The residual resistance is observed to be essentially uncorrelated with the other variables, but strongly dependent on the macroscop...

  10. Temperature dependence of the experimental penetration depth of superconducting thin films

    International Nuclear Information System (INIS)

    Fink, H.J.; Gruenfeld, V.; Pastawski, H.

    1982-01-01

    Experimental magnetic field penetration depths delta(t,d,H) of the stable and superheated Meissner state were calculated as a function of temperature for various applied magnetic fields and various film thicknesses for two cases: (1) lambda(t)/d<< kappa→infinity and (2) kappa< or approx. =2lambda(t)/d (lambda is the Ginzburg-Landau penetration depth, d is the film thickness, kappa is the GL parameter). The results of the first case should be a useful tool for obtaining lambda(0) of amorphous superconducting thin films

  11. Raman scattering diagnostics of YBa2Cu3Ox high temperature superconducting films

    International Nuclear Information System (INIS)

    Bagratashvili, V.N.; Burimov, V.N.; Denisov, V.N.

    1988-01-01

    Superconducting YBa 2 Cu 3 O x films produced by laser spraying of ceramic material are investigated by light Raman scattering (LCS). It is shown that using LCS it is possible to obtain data on phase composition and prevailing film orientation and to find optical conditions for their synthesis. The LCS method feature consists in a possibility of non-destructive remote control and high space resolution (several microns). Experimental results have shown that the best parameters (the highest T c and the narrowest Δ T c interval) are typical of films with prevailing orientation of 0 xy crystallite plane parallel to the surface

  12. Lanthanum gallate substrates for epitaxial high-temperature superconducting thin films

    International Nuclear Information System (INIS)

    Sandstrom, R.L.; Giess, E.A.; Gallagher, W.J.; Segmueller, A.; Cooper, E.I.; Chisholm, M.F.; Gupta, A.; Shinde, S.; Laibowitz, R.B.

    1988-01-01

    We demonstrate that lanthanum gallate (LaGaO 3 ) has considerable potential as an electronic substrate material for high-temperature superconducting films. It provides a good lattice and thermal expansion match to YBa 2 Cu 3 O/sub 7-//sub x/, can be grown in large crystal sizes, is compatible with high-temperature film processing, and has a reasonably low dielectric constant (ε≅25) and low dielectric losses. Epitaxial YBa 2 Cu 3 O/sub 7-//sub x/ films grown on LaGaO 3 single-crystal substrates by three techniques have zero resistance between 87 and 91 K

  13. Lanthanum gallate substrates for epitaxial high-temperature superconducting thin films

    Science.gov (United States)

    Sandstrom, R. L.; Giess, E. A.; Gallagher, W. J.; Segmuller, A.; Cooper, E. I.

    1988-11-01

    It is demonstrated that lanthanum gallate (LaGaO3) has considerable potential as an electronic substrate material for high-temperature superconducting films. It provides a good lattice and thermal expansion match to YBa2Cu3O(7-x), can be grown in large crystal sizes, is compatible with high-temperature film processing, and has a reasonably low dielectric constant and low dielectric losses. Epitaxial YBa2Cu3O(7-x) films grown on LaGaO3 single-crystal substrates by three techniques have zero resistance between 87 and 91 K.

  14. Influence of reversible epitactical stress on the electronic properties of thin superconducting films

    International Nuclear Information System (INIS)

    Trommler, Sascha

    2014-01-01

    In this thesis new stress techniques are applied on thin superconducting (La,Sr) 2 CuO 4 and BaFe 1.8 Co 0.2 As 2 films. At one hand piezoelectric substrates are applied, which make a biaxial stress of the thin film deposed there possible, whereby the lattice parameters of the substrate are altered by an electric field. At the other hand on the base of flexible substrates by means of a bending experiment a uniaxial lattice deformation of thin film is realized.

  15. Superconducting Film Flux Transformer for a Sensor of a Weak Magnetic Field

    International Nuclear Information System (INIS)

    Ichkitidze, L; Mironyuk, A

    2012-01-01

    The object of study is a superconducting film flux transformer in the form of a square shaped loop with the tapering operative strip used in a sensor of a weak magnetic field. The magnetosensitive film element based on the giant magnetoresistance effect is overlapped with the tapering operative strip of the flux transformer; it is separated from the latter by the insulator film. It is shown that the topological nanostructuring of the operative strip of the flux transformer increases its gain factor by one or more orders of magnitude, i.e. increases its efficiency, which leads to a significant improvement of important parameters of a magnetic-field sensor.

  16. Frustrated magnetic response of a superconducting Nb film with a square lattice of columnar defects

    Energy Technology Data Exchange (ETDEWEB)

    Zadorosny, R; Ortiz, W A [Grupo de Supercondutividade e Magnetismo, Departamento de Fisica, Universidade Federal de Sao Carlos, Sao Carlos, SP (Brazil); Lepienski, C M [Universidade Federal do Parana, Departamento de Fisica, Curitiba, PR (Brazil); Patino, E; Blamire, M G [Department of Materials Science, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom)], E-mail: rafazad@df.ufscar.br

    2008-02-01

    The magnetic response of a superconducting system presenting a frustrated state is investigated. The system is a superconducting film with mechanically pierced columns, cooled in a field which is then removed. Frustration originates from the competition between return flux of a dipole - created by flux trapped in the empty columns - and flux exclusion by the surrounding superconductor in the Meissner state. The system resolves the incompatibility among conflicting constraints, leading to frustration, by eliminating return flux, which is possibly assimilated by nearby columns, as manifested by a sudden reduction of the magnetic moment on the decreasing field branch of the hysteresis loop.

  17. Frustrated magnetic response of a superconducting Nb film with a square lattice of columnar defects

    International Nuclear Information System (INIS)

    Zadorosny, R; Ortiz, W A; Lepienski, C M; Patino, E; Blamire, M G

    2008-01-01

    The magnetic response of a superconducting system presenting a frustrated state is investigated. The system is a superconducting film with mechanically pierced columns, cooled in a field which is then removed. Frustration originates from the competition between return flux of a dipole - created by flux trapped in the empty columns - and flux exclusion by the surrounding superconductor in the Meissner state. The system resolves the incompatibility among conflicting constraints, leading to frustration, by eliminating return flux, which is possibly assimilated by nearby columns, as manifested by a sudden reduction of the magnetic moment on the decreasing field branch of the hysteresis loop

  18. Collective-pinning properties of superconducting a-NbxGe and a-MoxSi films

    International Nuclear Information System (INIS)

    Woerdenweber, R.

    1987-01-01

    This thesis describes a study of superconducting flux pinning in amorphous NbGe and MoSi films of various compositions and thickness. Amorphous NbGe and MoSi alloys belong to the weak-coupling type-II superconductors in the extreme dirty limit. This feature enables to determine several important superconducting parameters from well-known theoretical expressions. It is also responsible for the weak pinning, which is necessary to observe the two-dimensional collective pinning properties according to the Larkin-Ovchinnikov theory. (Auth.)

  19. Maximum permissible voltage of YBCO coated conductors

    Energy Technology Data Exchange (ETDEWEB)

    Wen, J.; Lin, B.; Sheng, J.; Xu, J.; Jin, Z. [Department of Electrical Engineering, Shanghai Jiao Tong University, Shanghai (China); Hong, Z., E-mail: zhiyong.hong@sjtu.edu.cn [Department of Electrical Engineering, Shanghai Jiao Tong University, Shanghai (China); Wang, D.; Zhou, H.; Shen, X.; Shen, C. [Qingpu Power Supply Company, State Grid Shanghai Municipal Electric Power Company, Shanghai (China)

    2014-06-15

    Highlights: • We examine three kinds of tapes’ maximum permissible voltage. • We examine the relationship between quenching duration and maximum permissible voltage. • Continuous I{sub c} degradations under repetitive quenching where tapes reaching maximum permissible voltage. • The relationship between maximum permissible voltage and resistance, temperature. - Abstract: Superconducting fault current limiter (SFCL) could reduce short circuit currents in electrical power system. One of the most important thing in developing SFCL is to find out the maximum permissible voltage of each limiting element. The maximum permissible voltage is defined as the maximum voltage per unit length at which the YBCO coated conductors (CC) do not suffer from critical current (I{sub c}) degradation or burnout. In this research, the time of quenching process is changed and voltage is raised until the I{sub c} degradation or burnout happens. YBCO coated conductors test in the experiment are from American superconductor (AMSC) and Shanghai Jiao Tong University (SJTU). Along with the quenching duration increasing, the maximum permissible voltage of CC decreases. When quenching duration is 100 ms, the maximum permissible of SJTU CC, 12 mm AMSC CC and 4 mm AMSC CC are 0.72 V/cm, 0.52 V/cm and 1.2 V/cm respectively. Based on the results of samples, the whole length of CCs used in the design of a SFCL can be determined.

  20. YBCO/manganite layered structures on NdGaO{sub 3} substrates

    Energy Technology Data Exchange (ETDEWEB)

    Nurgaliev, T [Institute of Electronics BAS, 72 Tsarigradsko Chaussee, 1784 Sofia (Bulgaria); Blagoev, B [Institute of Electronics BAS, 72 Tsarigradsko Chaussee, 1784 Sofia (Bulgaria); Donchev, T [Institute of Electronics BAS, 72 Tsarigradsko Chaussee, 1784 Sofia (Bulgaria); Miteva, S [Institute of Electronics BAS, 72 Tsarigradsko Chaussee, 1784 Sofia (Bulgaria); Mozhaev, P B [Institute of Physics and Technology RAS, Nakhimovsky ave. 36, 117218 Moscow (Russian Federation); Mozhaeva, J E [Institute of Physics and Technology RAS, Nakhimovsky ave. 36, 117218 Moscow (Russian Federation); Ovsyannikov, G A [Institute of Radio Engineering and Electronics RAS, Mokhovaya st.11, 103907 Moscow (Russian Federation); Kotelyanskii, I M [Institute of Radio Engineering and Electronics RAS, Mokhovaya st.11, 103907 Moscow (Russian Federation); Jacobsen, C [Technical University of Denmark, Building 307-309, DK-2800, Kgs.Lyngby, Denmark (Denmark)

    2006-06-01

    Results of deposition of YBa{sub 2}Cu{sub 3}O{sub 7-x}/CeO{sub 2}/(La{sub 0.7}Ca{sub 0.3}MnO{sub 3} or La{sub 0.7}Sr{sub 0.3}MnO{sub 3}) structures on the standard oriented and tilted ( 8{sup 0}) NdGaO{sub 3} substrates and results of investigation of electrical parameters of YBa{sub 2}Cu{sub 3}O{sub 7-x} (YBCO) films in such structures are presented. The YBCO component of the structure exhibits lower value of the critical parameters in comparison with those of single YBCO films. The contribution of the magnetic layer to the microwave losses of the YBCO film in the layered structure is evaluated.

  1. YBCO/manganite layered structures on NdGaO3 substrates

    International Nuclear Information System (INIS)

    Nurgaliev, T; Blagoev, B; Donchev, T; Miteva, S; Mozhaev, P B; Mozhaeva, J E; Ovsyannikov, G A; Kotelyanskii, I M; Jacobsen, C

    2006-01-01

    Results of deposition of YBa 2 Cu 3 O 7-x /CeO 2 /(La 0.7 Ca 0.3 MnO 3 or La 0.7 Sr 0.3 MnO 3 ) structures on the standard oriented and tilted ( 8 0 ) NdGaO 3 substrates and results of investigation of electrical parameters of YBa 2 Cu 3 O 7-x (YBCO) films in such structures are presented. The YBCO component of the structure exhibits lower value of the critical parameters in comparison with those of single YBCO films. The contribution of the magnetic layer to the microwave losses of the YBCO film in the layered structure is evaluated

  2. Vortex loops in the critical Casimir effect in superfluid and superconducting films

    International Nuclear Information System (INIS)

    Williams, Gary A.

    2004-01-01

    Vortex-loop renormalization techniques are used to calculate the magnitude of the critical Casimir forces in superfluid and superconducting thin films. The force is found to become appreciable when the size of the thermally excited vortex loops is comparable to the film thickness, and the results for T c are found to match very well with perturbative renormalization-group theories that can only be carried out for T>T c . In helium films the Casimir force leads to a change in the film thickness close to T c that has been observed experimentally. A similar effect is predicted to occur near the transition temperature of high-T c superconducting films, which is also a vortex-loop phase transition. In this case the Casimir force takes the form of a voltage difference that will appear at the junction between a thin film and a bulk sample. Estimates show that this voltage can be appreciable (tens of microvolts), and it may be possible to observe the effect by measuring the voltage across two Josephson tunnel junctions to the film and to the bulk, using a SQUID voltmeter

  3. Quasi-one-dimensional intermittent flux behavior in superconducting films

    DEFF Research Database (Denmark)

    Qviller, A. J.; Yurchenko, V. V.; Galperin, Y. M.

    2012-01-01

    Intermittent filamentary dynamics of the vortex matter in superconductors is found in films of YBa2Cu3O7-δ deposited on tilted substrates. Deposition of this material on such substrates creates parallel channels of easy flux penetration when a magnetic field is applied perpendicular to the film. ...

  4. Influence of ion beam mixing on the growth of high temperature oxide superconducting thin film

    International Nuclear Information System (INIS)

    Bordes, N.; Rollett, A.D.; Cohen, M.R.; Nastasi, M.

    1989-01-01

    The superconducting properties of high temperature superconductor thin films are dependent on the quality of the substrate used to grow these films. In order to maximize the lattice matching between the superconducting film and the substrate, we have used a YBa 2 Cu 3 O 7 thin film deposited on left-angle 100 right-angle SrTiO 3 as a template. The first film was prepared by coevaporation of Y, BaF 2 and Cu on left-angle 100 right-angle SrTiO 3 , followed by an anneal in ''wet'' oxygen at 850 degree C. This film showed a sharp transition at about 90 K. A thicker layer of about 5000 A was then deposited on top of this first 2000 angstrom film, using the same procedure. After the post anneal at 850 degree C, the transition took place at 80 K and no epitaxy of the second film was observed. Ion beam mixing at 400 degree C, using 400 keV O ions was done at the interface of the two films (the second one being not annealed). After the post anneal, the film displayed an improved Tc at 90K. Moreover, epitaxy was shown to take place from the interface SrTiO 3 -123 film towards the surface and was dependent of the dose. These results will be discussed from the data obtained from Rutherford backscattering spectroscopy (RBS) combined with channeling experiments, x-ray diffraction (XRD) and scanning electron microscopy (SEM) observations. 8 refs., 2 figs., 2 tabs

  5. Application of High-Temperature Superconducting Thin-Film Devices to Electro-Optical and Electronic Warfare Systems

    Science.gov (United States)

    1990-02-01

    superconducting dispersive (chirp) delay line. Bt currents (IB 1 and 1B 2) control states of write junctions (gates 1 and 2). (Counter) clockwise currents...Gavaler, and "S. A. Reihle, "Superconductive Convolver with June- A. I. Braginski, "Optical Response of Epitaxial Films tion Ring Nlixers," IELT Trans

  6. Anomalous magnetism of superconducting Mg-doped InN film

    Directory of Open Access Journals (Sweden)

    P. H. Chang

    2016-02-01

    Full Text Available We report on the Meissner effect of Mg-doped InN film with superconducting transition onset temperature Tc,onset of 5 K. Mg-doped InN is magnetically ordered and exhibits a simultaneous first-order magnetic and electric transition near 50 K. Its behavior is similar to that of iron-based superconductors. A strong correlation is proposed to exist between structural distortion and superconductivity when Mg is doped into InN. The suppression of magnetic ordering close to Tc by doping is further demonstrated by anisotropic magnetoresistance and M-H measurements. The findings suggest that the superconducting mechanism in the system may not be conventional BCS.

  7. Superconductivity of Rock-Salt Structure LaO Epitaxial Thin Film.

    Science.gov (United States)

    Kaminaga, Kenichi; Oka, Daichi; Hasegawa, Tetsuya; Fukumura, Tomoteru

    2018-06-06

    We report a superconducting transition in a LaO epitaxial thin film with the superconducting transition onset temperature ( T c ) at around 5 K. This T c is higher than those of other lanthanum monochalcogenides and opposite to their chemical trend: T c = 0.84, 1.02, and 1.48 K for LaX (X = S, Se, Te), respectively. The carrier control resulted in a dome-shaped T c as a function of electron carrier density. In addition, the T c was significantly sensitive to epitaxial strain in spite of the highly symmetric crystal structure. This rock-salt superconducting LaO could be a building block to design novel superlattice superconductors.

  8. Related electrical, superconducting and structural characteristics of low temperature indium films

    International Nuclear Information System (INIS)

    Belevtsev, B.I.; Pilipenko, V.V.; Yatsuk, L.Ya.

    1981-01-01

    Reported are results of a complex study of electrical, superconducting and structural properties of indium films vacuum evaporated onto a liquid helium-cooled substrate. Structural electron diffraction investigations gave a better insight into the general features of the annealing during the warming-up of cold-deposited films. It is found that the annealing of indium films to about 80 to 100 K entails an irreversible growth of interplanar separations due to decreasing inhomogeneous microstresses. As the films are warmed from 100 to 300 K, the principal annealing processes are determined by crystallite growth and development of dominating orientation. The changes in the residual resistance and in Tsub(c) with warming the cold-deported films are explained on the base of structural data obtained. In particular, a direct relationship is revealed between the crystallite size and Tsub(c) [ru

  9. Electro-physical properties of superconducting ceramic thick film prepared by partial melting method.

    Science.gov (United States)

    Lee, Sang Heon

    2013-05-01

    BiSrCaCuO superconductor thick films were prepared at several curing temperatures, and their electro-physical properties were determined to find an optimum fabrication conditions. Critical temperatures of the superconductors were decreased with increasing melting temperature, which was related to the amount of equilibrium phases of the superconducting materials with temperature. The critical temperature of BiSrCaCuO bulk and thick film superconductors were 107 K and 96 K, respectively. The variation of susceptibility of the superconductor thick film formed at 950 degrees C had multi-step-type curve for 70 G externally applied field, whereas, a superconductor thick film formed at 885 degrees C had a single step-type curve like a bulk BiSrCaCuO ceramic superconductor in the temperature-susceptibility curves. A partial melting at 865 degrees C is one of optimum conditions for making a superconductor thick film with a relatively homogeneous phase.

  10. Growth and applications of superconducting Y-Ba-Cu-O thin films

    International Nuclear Information System (INIS)

    Pinto, R.

    1991-01-01

    This paper attempt to highlight the important PVD techniques such as evaporation, sputtering, ion beam deposition and excimer laser ablation for the preparation of superconducting YBaCuO thin films. Since enormous amount of work has been published over the last few years, this review is not comprehensive even in PVD techniques. In the area of applications for electronics, thin film appear to be much more promising than bulk high T c superconductors. Already high J c values in the region of 4 x 10 6 A cm -2 have been realized in thin films. Resonators and transmission lines have been fabricated using 123 films showing a transmission loss significantly lower than that of copper at 77 degrees K at X-band frequencies. This review will discuss some of the important electronic applications feasible with 123 films

  11. Superconductivity

    CERN Document Server

    Poole, Charles P; Creswick, Richard J; Prozorov, Ruslan

    2014-01-01

    Superconductivity, Third Edition is an encyclopedic treatment of all aspects of the subject, from classic materials to fullerenes. Emphasis is on balanced coverage, with a comprehensive reference list and significant graphics from all areas of the published literature. Widely used theoretical approaches are explained in detail. Topics of special interest include high temperature superconductors, spectroscopy, critical states, transport properties, and tunneling. This book covers the whole field of superconductivity from both the theoretical and the experimental point of view. This third edition features extensive revisions throughout, and new chapters on second critical field and iron based superconductors.

  12. Direct growth of superconducting NdFeAs(O,F) thin films by MBE

    Energy Technology Data Exchange (ETDEWEB)

    Chihara, Masashi, E-mail: chihara@iku.xtal.nagoya-u.ac.jp [Department of Crystalline Materials Science, Nagoya University, Chikusa-ku, Nagoya 464-8603 (Japan); Sumiya, Naoki; Arai, Kenta [Department of Crystalline Materials Science, Nagoya University, Chikusa-ku, Nagoya 464-8603 (Japan); Ichinose, Ataru; Tsukada, Ichiro [Central Research Institute of Electric Power Industry, Yokosuka-shi, Kanagawa 240-0101 (Japan); Hatano, Takafumi; Iida, Kazumasa; Ikuta, Hiroshi [Department of Crystalline Materials Science, Nagoya University, Chikusa-ku, Nagoya 464-8603 (Japan)

    2015-11-15

    Highlights: • Highly textured NdFeAs(O,F) thin films were obtained by a direct growth method. • Enhancing the migration was crucial to realize the direct growth. • The critical current density exceeded 3 MA/cm{sup 2} at self-field and 1 MA/cm{sup 2} at 9 T. • A two-dimensional growth was confirmed by the observation of surface morphology. - Abstract: We report on the growth of NdFeAs(O,F) superconducting thin films by molecular beam epitaxy without having a NdOF secondary layer that was necessary for fluorine doping in our previous studies. The key to realizing the direct growth of a superconducting film was the enhancement of migration of the raw materials on the substrate, which was accomplished by two steps. Firstly, we increased the growth temperature that improved the crystalline quality of parent NdFeAsO thin films. Secondly, the atmosphere in the chamber during the growth was improved by changing the crucible material of the Fe source cell. Highly textured NdFeAs(O,F) thin films with critical temperatures up to 50 K were obtained, and terraces were observed by atomic force microscope, indicating a two-dimensional growth. However, precipitates were also found on the surface, which suggests that enhancing further the migration is necessary for obtaining a NdFeAs(O,F) thin film with a better quality.

  13. Quasi-one-dimensional intermittent flux behavior in superconducting films

    OpenAIRE

    Qviller, A. J.; Yurchenko, V. V.; Galperin, Y. M.; Vestgården, J. I.; Mozhaev, Peter; Hansen, Jørn Bindslev; Johansen, T. H.

    2012-01-01

    Intermittent filamentary dynamics of the vortex matter in superconductors is found in films of YBa_{2}Cu_{3}O_{7-δ} deposited on tilted substrates. Deposition of this material on such substrates creates parallel channels of easy flux penetration when a magnetic field is applied perpendicular to the film. As the applied field is gradually increased, magneto-optical imaging reveals that flux penetrates via numerous quasi-one-dimensional jumps. The distribution of flux avalanche sizes follows a ...

  14. Lead-doped electron-beam-deposited Bi-Sr-Ca-Cu-O superconducting thin films

    Energy Technology Data Exchange (ETDEWEB)

    Agnihotry, S.A.; Saini, K.K.; Kant, C.; Sharma, C.P.; Ekbote, S.N.; Asthana, P.; Nagpal, K.C.; Chandra, S. (National Physical Lab., New Delhi (India))

    1991-03-20

    Superconducting thin films of the lead-doped Bi-Sr-Ca-Cu-O system have been prepared on (100) single-crystal SrTiO{sub 3} substrates by an electron beam deposition technique using a single sintered pellet as the evaporation source. As-deposited films are amorphous and non-superconducting; post-deposition annealing at an optimized temperature in air has been found to result in crystalline and superconducting films. The superconducting characteristics of the films have been observed to be sensitive not only to the duration and temperature of post-deposition annealing but also to the lead content and the sintering parameters for the pellet to be used as the evaporation source. A pellet with nominal composition Bi{sub 3}Pb{sub 1}Sr{sub 3}Ca{sub 3}Cu{sub 4}O{sub y} that had been sintered for 200 h zero resistivity Tc{sup 0}=112 K. However, films deposited using such a pellet as the evaporation source had Tc{sup 0} {approx equal} 73-78 K, as had the films deposited from a pellet without any lead. We investigated systematically films deposited from pellets with more lead and sintered for different durations. It is evident from these investigations that pellets with nominal composition Bi{sub 3}Pb{sub 2}Sr{sub 3}Ca{sub 3}Cu{sub 4}O{sub y}, i.e. with an excess of lead, and sintered for about 75 h when used as the evaporation source yield films with Tc{sup 0} {approx equal} 100 K when annealed between 835 and 840deg C for an optimized long duration. The films are characterized by X-ray diffraction and energy-dispersive spectroscopy techniques and have been found to be highly c axis oriented. The effect of lead in promoting a high Tc{sup 0}=110 K phase seems to be similar to that in bulk ceramics. (orig.).

  15. Ultrasensitive interplay between ferromagnetism and superconductivity in NbGd composite thin films

    Science.gov (United States)

    Bawa, Ambika; Gupta, Anurag; Singh, Sandeep; Awana, V. P. S.; Sahoo, Sangeeta

    2016-01-01

    A model binary hybrid system composed of a randomly distributed rare-earth ferromagnetic (Gd) part embedded in an s-wave superconducting (Nb) matrix is being manufactured to study the interplay between competing superconducting and ferromagnetic order parameters. The normal metallic to superconducting phase transition appears to be very sensitive to the magnetic counterpart and the modulation of the superconducing properties follow closely to the Abrikosov-Gor’kov (AG) theory of magnetic impurity induced pair breaking mechanism. A critical concentration of Gd is obtained for the studied NbGd based composite films (CFs) above which superconductivity disappears. Besides, a magnetic ordering resembling the paramagnetic Meissner effect (PME) appears in DC magnetization measurements at temperatures close to the superconducting transition temperature. The positive magnetization related to the PME emerges upon doping Nb with Gd. The temperature dependent resistance measurements evolve in a similar fashion with the concentration of Gd as that with an external magnetic field and in both the cases, the transition curves accompany several intermediate features indicating the traces of magnetism originated either from Gd or from the external field. Finally, the signatures of magnetism appear evidently in the magnetization and transport measurements for the CFs with very low (<1 at.%) doping of Gd.

  16. LaNiO(3) Buffer Layers for High Critical Current Density YBa(2)Cu(3)O(7-delta) and Tl(2)Ba(2)CaCu(2)O(8-delta) Films

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, C.M.; Parilla, P.A.; Siegal, M.P.; Ginley, D.S.; Wang, Y.-T.; Blaugher, R.D.; Price, J.C.; Overmyer, D.L.; Venturini, E.L.

    1999-08-24

    We demonstrate high critical current density superconducting films of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} (YBCO) and Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub 8{minus}{delta}} (Tl-2212) using LaNiO{sub 3} (LNO) buffer layers. YBCO films grown on an LNO buffer layer have only a slightly lower J{sub c} (5K, H=0) than films grown directly on a bare LaAlO{sub 3} substrate. It is noteworthy that YBCO films grown on LNO buffer layers exhibit minor microstructural disorder and enhanced flux pinning. LNO-buffered Tl-2212 samples show large reductions in J{sub c} at all temperatures and fields compared to those grown on bare LaAlO{sub 3}, correlating to both a-axis grain and nonsuperconducting phase formation. With additional optimization, LNO could be a promising buffer layer for both YBCO and Tl-based superconducting films, perhaps ideally suited for coated conductor applications.

  17. Ultrathin NbN film superconducting single-photon detector array

    International Nuclear Information System (INIS)

    Smirnov, K; Korneev, A; Minaeva, O; Divochiy, A; Tarkhov, M; Ryabchun, S; Seleznev, V; Kaurova, N; Voronov, B; Gol'tsman, G; Polonsky, S

    2007-01-01

    We report on the fabrication process of the 2 x 2 superconducting single-photon detector (SSPD) array. The SSPD array is made from ultrathin NbN film and is operated at liquid helium temperatures. Each detector is a nanowire-based structure patterned by electron beam lithography process. The advances in fabrication technology allowed us to produce highly uniform strips and preserve superconducting properties of the unpatterned film. SSPD exhibit up to 30% quantum efficiency in near infrared and up to 1% at 5-μm wavelength. Due to 120 MHz counting rate and 18 ps jitter, the time-domain multiplexing read-out is proposed for large scale SSPD arrays. Single-pixel SSPD has already found a practical application in non-invasive testing of semiconductor very-large scale integrated circuits. The SSPD significantly outperformed traditional single-photon counting avalanche diodes

  18. Simulation of YBCO Tape and Coils in HTS Maglev System

    Directory of Open Access Journals (Sweden)

    Song Mengxiao

    2017-01-01

    Full Text Available In the process of running high temperature superconducting maglev train, the AC(Alternating Current loss of superconducting coil is directly related to its safe operation and operating cost. In this paper, the simulation model was built based on the finite element software COMSOL Multiphysics, and mainly simulated and calculated the AC losses of YBCO(Yttrium Barium Copper Oxide tape and coils. In this model, as the solving object, the singular and infinite long YBCO tape and coils model was solved with H-formulation and the nonlinear characteristic (E-J constitutive law and anisotrophy (B-J characteristic were taken into consideration as the theoretical foundation. Then on the basis of the model under maglev suspension system, AC losses under different amplitude and frequence AC currents were calculated. The results shows that under different frequencies and dynamic components, the local maximum AC loss of YBCO tape and coils occurs when the steady-state DC(Direct Current current is 30A. Then comparing with old maglev suspension system, the new system can greatly reduce the energy consumption and the material cost.

  19. Structure and superconducting properties of Nb-Zr alloy films made by a high-rate sputtering

    International Nuclear Information System (INIS)

    Sekine, Hisashi; Inoue, Kiyoshi; Tachikawa, Kyoji

    1978-01-01

    Superconducting Nb-Zr alloy films have been prepared by a continuous high-rate sputtering on tantalum substrates. A deposition rate of 330 nm/min has been attained. The compositional profile in the Nb-Zr film is quite uniform and the film has nearly the same composition as that of the target. The films deposited in a pure argon atmosphere show a columnar structure grown perpendicular to the substrate. The grain size strongly depends on the substrate temperature. The phase transformations in the Nb-Zr film become more apparent and the structure becomes closer to the equilibrium state as the film is deposited in higher atmosphere pressures and/or at lower target voltages. The superconducting transition temperature T sub(c) of the films is about the same as that of bulk samples. The dependence of T sub(c) on the substrate temperature is explainable on the phase transformations in the film. Critical current density J sub(c) and its anisotropy is closely related to the grain structure of the film. Grain boundaries seem to act as the most predominant flux pinning centers in the films. Effects of oxygen in the sputtering atmosphere on the structure and superconducting properties of the Nb-Zr films have been also investigated. Oxygen significantly decreases the grain size of the film. Oxygen increases J sub(c) but decreases T sub(c) of the film. (auth.)

  20. In-plane aligned YBCO tape on textured YSZ buffer layer deposited on stainless steel substrate by laser ablation only with O{sup +} ion beam assistance

    Energy Technology Data Exchange (ETDEWEB)

    Huang Xintang [Huazhong Univ. of Sci. and Technol., Wuhan (China). Nat. Lab. of Laser Technol.]|[Huazhong Normal Univ., Wuhan, HB (China). Dept. of Physics; Wang Youqing; Wang Qiuliang; Chen Qingming [Huazhong Univ. of Sci. and Technol., Wuhan (China). Nat. Lab. of Laser Technol.

    1999-08-16

    In this paper we have prepared YSZ buffer layers on stainless steel substrates by laser ablation only with O{sup +} ion beam assistance and YBCO films on YSZ/steel consequently. The relevant parameters of YSZ and YBCO film deposition are indicated. (orig.) 8 refs.

  1. In-plane aligned YBCO tape on textured YSZ buffer layer deposited on stainless steel substrate by laser ablation only with O+ ion beam assistance

    International Nuclear Information System (INIS)

    Huang Xintang; Huazhong Normal Univ., Wuhan, HB; Wang Youqing; Wang Qiuliang; Chen Qingming

    1999-01-01

    In this paper we have prepared YSZ buffer layers on stainless steel substrates by laser ablation only with O + ion beam assistance and YBCO films on YSZ/steel consequently. The relevant parameters of YSZ and YBCO film deposition are indicated. (orig.)

  2. Preparation and analysis of superconducting Nb-Ge films

    International Nuclear Information System (INIS)

    Testardi, L.R.; Meek, R.L.; Poate, J.M.; Royer, W.A.; Storm, A.R.; Wernick, J.H.

    1975-01-01

    The dependences of T/subc/, resistivity, resistance ratio, and structure on chemical composition and sputtering conditions for Nb-Ge films have been studied. The chemical composition, impurity content, and x-ray structure were obtained using Rutherford backscattering, nuclear techniques, and x-ray diffraction. Although T/subc/ varies with composition, it is not found to be critically dependent upon exact stoichiometry; the Nb/Ge ratios vary by approx. 13% (2.6 to 3) for films with approx. 23-K onsets and by approx. 40% (2.2 to 3.3) for films with approx. 20-K onsets. For compositions similar to the bulk, the films have comparitively much higher T/subc/'s and smaller lattice parameters. X-ray results show the films to contain predominately A-15 phase (except for Nb/Ge less-than or equal to 2.5) with lattice parameters varying from 5.15 A for Nb-rich low-T/subc/ films to 5.12 A for Ge-rich films. Several percent of oxygen and carbon occur in low-T/subc/ amorphous films deposited at 650 degreeC but this is considerably reduced in high-T/subc/ films made simultaneously at approx. 750 degreeC. No argon was found and the nitrogen content was generally less than 1%. No correlation of high T/subc/'s and impurities was found. The optimum deposition temperature and resistivity are lowest, and the resistance ratio highest for Nb/Ge ratios somewhat below 3/1. A simple correlation of T/subc/ and resistance ratio is reported which is largely independent of all sputtering conditions and composition and which suggests that slightly higher T/subc/'s may be possible. Negative bias was found to be detrimental to T/subc/ while positive bias had relatively little effect. Magnetic-field-assisted sputtering led to significant increases in the sputtering rate and the optimum deposition temperature

  3. Far-infrared electrodynamics of thin superconducting NbN film in magnetic fields

    Czech Academy of Sciences Publication Activity Database

    Šindler, Michal; Tesař, Roman; Koláček, Jan; Szabó, P.; Samuely, P.; Hašková, V.; Kadlec, Christelle; Kadlec, Filip; Kužel, Petr

    2014-01-01

    Roč. 27, č. 5 (2014), 1-8 ISSN 0953-2048 R&D Projects: GA ČR(CZ) GAP204/11/0015; GA MŠk(CZ) LD14060 Institutional support: RVO:68378271 Keywords : superconductivity * thin films * scanning tunneling spectroscopy * time-domain terahertz spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.325, year: 2014

  4. Superconductivity in volumetric and film ceramics Bi-Sr-Ca-Cu-O

    Energy Technology Data Exchange (ETDEWEB)

    Sukhanov, A A; Ozmanyan, Kh R; Sandomirskij, B B

    1988-07-10

    A superconducting transition with T/sub c0/=82-95 K and T/sub c/(R=0)=82-72 K was observed in volumetric and film Bi(Sr/sub 1-x/Ca/sub x/)/sub 2/Cu/sub 3/O/sub y/ samples obtained by solid-phase reaction. Temperature dependences of resistance critical current and magnetic susceptibility are measured.

  5. Influence of stabilizer thickness on over-current test of YBCO-coated conductors

    International Nuclear Information System (INIS)

    Kwon, N Y; Kim, H S; Kim, K L; Lee, H G; Yim, S W; Kim, H-R; Hyun, O-B; Kim, H M

    2009-01-01

    The increased use of distributed power generation has led to increasingly high fault current levels. A superconducting fault current limiter (SFCL) is a potential solution to prevent the problem of short-circuit currents. YBCO-coated conductors (CCs) are one of the most promising superconducting materials for SFCLs. Most YBCO CCs have stabilizers, which play a significant role in limiting the fault current in the SFCL. Therefore, the selection of the appropriate material and the thickness of the stabilizer of the CC used for the SFCL may affect its quench/recovery characteristics. In this paper, the quench/recovery characteristics of YBCO CC tapes having stabilizers with various thicknesses were investigated. The quench/recovery test results showed that, as the thickness of the stabilizer decreased, both the final approach temperature and the recovery time decreased.

  6. Depth profiling of transport properties of in-situ grown YBa_2Cu_3O_7-x films for coated conductor applications

    Science.gov (United States)

    Jo, William; Huh, J.-U.; Hammond, R. H.; Beasley, M. R.

    2003-03-01

    We report depth profiling of the local critical current density and resistivity of YBa_2Cu_3O_7-x (YBCO) films grown by in-situ electron beam evaporation. The method provides important information on the uniformity of the films, and therefore on the commonly observed property that the critical currents of coated conductor high temperature superconductor films do not scale linearly with thickness. Using a methodology of layer-by-layer etching, depth profiling of critical currents and resistivity of the films has been achieved. We use a Bromine methanol mixture to etch down YBCO films with an etch rate of 60 nm/min. At each step, we also observe surface morphology using high resolution scanning electron microscopy. In this talk, we report further study of the results found earlier that YBCO films deposited at high rates are composed of an upper layer of defected YBCO with a local Jc of 5 - 7 MA/cm^2 and a lower more perfect layer with no critical current capacity. The information derived may be useful in the characterization and optimization of superconducting thin films for electrical power and other applications.

  7. High current densities in superconducting films from magnetization

    International Nuclear Information System (INIS)

    McGuire, T.R.; Gupta, A.; Koren, G.; Gross, R.

    1990-01-01

    Epitaxial thin films of YBa 2 Cu 3 O 7-x made by laser ablation have the CuO planes parallel to the film surface. In the CuO planes critical currents of J C ∼40 x 10 6 amps/cm 2 are found at 5K in zero field. Multi-layered films with Gd replacing Y each .01μm in thickness have J C nearly 140 x 10 6 amps/cm 2 . This higher value is perhaps due to additional point defects. Perpendicular to the CuO planes magnetization studies indicate strong pinning effects attributed to the CuO planes acting as barriers to flux motion

  8. Effect of BaZrO3/Ag hybrid doping to the microstructure and performance of fluorine-free MOD method derived YBa2Cu3O7−x superconducting thin films

    DEFF Research Database (Denmark)

    Tang, Xiao; Yue, Zhao; Wu, W.

    2015-01-01

    It is known that BaZrO3 and Ag can improve the magnetic and transport performance of YBCO thin film through totally disparate ways. BaZrO3 plays the role of flux pinning centers and Ag improves the transparency of the YBCO grain boundaries. However, similar research is rare on the fluorine-free d...

  9. Model of vortex dynamics in superconducting films in two-coil measurements of the coherence length

    Science.gov (United States)

    Lemberger, Thomas; Loh, Yen Lee

    In two-coil measurements on superconducting films, a magnetic field from a small coil is applied to the center of the film. When the amplitude of the ac field is increased, the film undergoes a transition from the ``Meissner'' state to a state with vortices and antivortices. Ultimately, the vortex density matches the applied magnetic field and field screening is negligible. Experimentally, the field at the transition is related to the superconducting coherence length, although a full theory of the relationship is lacking. We show that the mutual inductance between drive and pickup coils, on opposite sides of the film, as a function of ac field amplitude is well-described by a phenomenological model in which vortices and antivortices appear together in the film at the radius where the induced supercurrent is strongest, and then they move through a landscape of moderately strong vortex pinning sites. Work at OSU supported by DOE-Basic Energy Sciences through Grant No. FG02-08ER46533.

  10. Depth profiling of superconducting thin films using rare gas ion sputtering with laser postionization

    International Nuclear Information System (INIS)

    Pallix, J.B.; Becker, C.H.; Missert, N.; Char, K.; Hammond, R.H.

    1988-01-01

    Surface analysis by laser ionization (SALI) has been used to examine a high-T/sub c/ superconducting thin film of nominal composition YBa 2 Cu 3 O 7 deposited on SrTiO 3 (100) by reactive magnetron sputtering. The main focus of this work was to probe the compositional uniformity and the impurity content throughout the 1800 A thick film having critical current densities of 1 to 2 x 10 6 A/cm 2 . SALI depth profiles show this film to be more uniform than thicker films (∼1 μm, prepared by electron beam codeposition) which were studied previously, yet the data show that some additional (non-superconducting) phases derived from Y, Ba, Cu, and O are still present. These additional phases are studied by monitoring the atomic and diatomic-oxide photoion profiles and also the depth profiles of various clusters (e.g. Y 2 O 2 + , Y 2 O 3 + , Y 3 O 4 + , Ba 2 O + , Ba 2 O 2 + , BaCu + , BaCuO + , YBaO 2 + , YSrO 2 + , etc.). A variety of impurities are observed to occur throughout the film including rather large concentrations of Sr. Hydroxides, F, Cl, and CO/sub x/ are evident particularly in the sample's near surface region (the top ∼100 A)

  11. Depth profiling of superconducting thin films using rare gas ion sputtering with laser postionization

    Science.gov (United States)

    Pallix, J. B.; Becker, C. H.; Missert, N.; Char, K.; Hammond, R. H.

    1988-02-01

    Surface analysis by laser ionization (SALI) has been used to examine a high-Tc superconducting thin film of nominal composition YBa2Cu3O7 deposited on SrTiO3 (100) by reactive magnetron sputtering. The main focus of this work was to probe the compositional uniformity and the impurity content throughout the 1800 Å thick film having critical current densities of 1 to 2×106 A/cm2. SALI depth profiles show this film to be more uniform than thicker films (˜1 μm, prepared by electron beam codeposition) which were studied previously, yet the data show that some additional (non-superconducting) phases derived from Y, Ba, Cu, and O are still present. These additional phases are studied by monitoring the atomic and diatomic-oxide photoion profiles and also the depth profiles of various clusters (e.g. Y2O2+, Y2O3+, Y3O4+, Ba2O+, Ba2O2+, BaCu+, BaCuO+, YBaO2+, YSrO2+, etc.). A variety of impurities are observed to occur throughout the film including rather large concentrations of Sr. Hydroxides, F, Cl, and COx are evident particularly in the sample's near surface region (the top ˜100 Å).

  12. Thin film metrology and microwave loss characterization of indium and aluminum/indium superconducting planar resonators

    Science.gov (United States)

    McRae, C. R. H.; Béjanin, J. H.; Earnest, C. T.; McConkey, T. G.; Rinehart, J. R.; Deimert, C.; Thomas, J. P.; Wasilewski, Z. R.; Mariantoni, M.

    2018-05-01

    Scalable architectures characterized by quantum bits (qubits) with low error rates are essential to the development of a practical quantum computer. In the superconducting quantum computing implementation, understanding and minimizing material losses are crucial to the improvement of qubit performance. A new material that has recently received particular attention is indium, a low-temperature superconductor that can be used to bond pairs of chips containing standard aluminum-based qubit circuitry. In this work, we characterize microwave loss in indium and aluminum/indium thin films on silicon substrates by measuring superconducting coplanar waveguide resonators and estimating the main loss parameters at powers down to the sub-photon regime and at temperatures between 10 and 450 mK. We compare films deposited by thermal evaporation, sputtering, and molecular beam epitaxy. We study the effects of heating in a vacuum and ambient atmospheric pressure as well as the effects of pre-deposition wafer cleaning using hydrofluoric acid. The microwave measurements are supported by thin film metrology including secondary-ion mass spectrometry. For thermally evaporated and sputtered films, we find that two-level state are the dominant loss mechanism at low photon number and temperature, with a loss tangent due to native indium oxide of ˜ 5 × 10 - 5 . The molecular beam epitaxial films show evidence of the formation of a substantial indium-silicon eutectic layer, which leads to a drastic degradation in resonator performance.

  13. Enhanced superconductivity and superconductor to insulator transition in nano-crystalline molybdenum thin films

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Shilpam; Amaladass, E.P. [Condensed Matter Physics Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Sharma, Neha [Surface & Nanoscience Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Harimohan, V. [Condensed Matter Physics Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Amirthapandian, S. [Materials Physics Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Mani, Awadhesh, E-mail: mani@igcar.gov.in [Condensed Matter Physics Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India)

    2017-06-01

    Disorder driven superconductor to insulator transition via intermediate metallic regime is reported in nano-crystalline thin films of molybdenum. The nano-structured thin films have been deposited at room temperature using DC magnetron sputtering at different argon pressures. The grain size has been tuned using deposition pressure as the sole control parameter. A variation of particle sizes, room temperature resistivity and superconducting transition has been studied as a function of deposition pressure. The nano-crystalline molybdenum thin films are found to have large carrier concentration but very low mobility and electronic mean free path. Hall and conductivity measurements have been used to understand the effect of disorder on the carrier density and mobilities. Ioffe-Regel parameter is shown to correlate with the continuous metal-insulator transition in our samples. - Highlights: • Thin films of molybdenum using DC sputtering have been deposited on glass. • Argon background pressure during sputtering was used to tune the crystallite sizes of films. • Correlation in deposition pressure, disorder and particle sizes has been observed. • Disorder tuned superconductor to insulator transition along with an intermediate metallic phase has been observed. • Enhancement of superconducting transition temperature and a dome shaped T{sub C} vs. deposition pressure phase diagram has been observed.

  14. Bi--Sr--Ca--Cu--O superconducting films fabricated using metal alkoxides

    International Nuclear Information System (INIS)

    Katayama, S.; Sekine, M.

    1991-01-01

    Superconducting films in the Bi--Sr--Ca--Cu--O systems were made using metal alkoxides. To prepare a dip-coating solution using a mixed alkoxide solution, insoluble Cu and Bi alkoxides were dissolved by modification with 2-dimethylaminoethanol and formation of a double alkoxide, respectively. Formation of the double alkoxides of Bi with Ca or Sr was confirmed using FT-IR and 1 H-NMR. Bi--Sr--Ca--Cu--O films on yttria-stabilized ZrO 2 and single crystal MgO(100) substrates were made using this solution. The films were closely oriented along the c-axis perpendicular to the substrate. The film on MgO(100) fired at 850 degree C for 48 h showed two resistance drops around 115 and 85 K, corresponding to the high-T c and low-T c phases, respectively, and zero resistance at 72 K

  15. Investigation on orientation, epitaxial growth and microstructure of a-axis-, c-axis-, (103)/(110)- and (113)-oriented YBa2Cu3O7-δ films prepared on (001), (110) and (111) SrTiO3 single crystal substrates by spray atomizing and coprecipitating laser chemical vapor deposition

    Science.gov (United States)

    Zhao, Pei; Wang, Ying; Huang, Zhi liang; Mao, Yangwu; Xu, Yuan Lai

    2015-04-01

    a-axis-, c-axis-, (103)/(110)- and (113)-oriented YBa2Cu3O7-δ (YBCO) films were pareared by spray atomizing and coprecipitating laser chemical vapor deposition. The surface of the a-axis-oriented YBCO film consisted of rectangular needle-like grains whose in-plane epitaxial growth relationship was YBCO [100] // STO [001] (YBCO [001] // STO [100]), and that of the c-axis-oriented YBCO film consisted of dense flat surface with epitaxial growth relationship of YBCO [001] // STO [001] (YBCO [100] //STO [100]). For the (103)/(110)-oriented and (113)-oriented YBCO film, they showed wedge-shaped and triangle-shaped grains, with corresponding in-plane epitaxial growth relationship of YBCO [110] // STO [110] (YBCO [010] // STO [010]) and YBCO [100] // STO [100] (YBCO [113] // STO [111], respectively.

  16. Thermal coupling effect on the vortex dynamics of superconducting thin films: time-dependent Ginzburg–Landau simulations

    Science.gov (United States)

    Jing, Ze; Yong, Huadong; Zhou, Youhe

    2018-05-01

    In this paper, vortex dynamics of superconducting thin films are numerically investigated by the generalized time-dependent Ginzburg–Landau (TDGL) theory. Interactions between vortex motion and the motion induced energy dissipation is considered by solving the coupled TDGL equation and the heat diffusion equation. It is found that thermal coupling has significant effects on the vortex dynamics of superconducting thin films. Branching in the vortex penetration path originates from the coupling between vortex motion and the motion induced energy dissipation. In addition, the environment temperature, the magnetic field ramp rate and the geometry of the superconducting film also greatly influence the vortex dynamic behaviors. Our results provide new insights into the dynamics of superconducting vortices, and give a mesoscopic understanding on the channeling and branching of vortex penetration paths during flux avalanches.

  17. Contactless determination of critical current density of superconducting films

    Czech Academy of Sciences Publication Activity Database

    Janů, Zdeněk; Švindrych, Zdeněk; Baničová, L.

    2012-01-01

    Roč. 22, č. 3 (2012), "9500804-1"-"9500804-4" ISSN 1051-8223 R&D Projects: GA MŠk(CZ) ME10069 Institutional research plan: CEZ:AV0Z10100520 Keywords : ac susceptibility * critical state * thin films Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.199, year: 2012

  18. Macroscopic Magnetic Coupling Effect: The Physical Origination of a High-Temperature Superconducting Flux Pump

    Science.gov (United States)

    Wang, Wei; Coombs, Tim

    2018-04-01

    We have uncovered at the macroscopic scale a magnetic coupling phenomenon in a superconducting YBa2Cu3O7 -δ (YBCO) film, which physically explains the mechanism of the high-temperature superconducting flux pump. The coupling occurs between the applied magnetic poles and clusters of vortices induced in the YBCO film, with each cluster containing millions of vortices. The coupling energy is verified to originate from the inhomogeneous field of the magnetic poles, which reshapes the vortex distribution, aggregates millions of vortices into a single cluster, and accordingly moves with the poles. A contrast study is designed to verify that, to provide the effective coupling energy, the applied wavelength must be short while the field amplitude must be strong, i.e., local-field inhomogeneity is the crucial factor. This finding broadens our understanding of the collective vortex behavior in an applied magnetic field with strong local inhomogeneity. Moreover, this phenomenon largely increases the controlled vortex flow rate by several orders of magnitude compared with existing methods, providing motivation for and physical support to a new branch of wireless superconducting dc power sources, i.e., the high-temperature superconducting flux pump.

  19. Superconductivity

    International Nuclear Information System (INIS)

    Narlikar, A.V.

    1993-01-01

    Amongst the numerous scientific discoveries that the 20th century has to its credit, superconductivity stands out as an exceptional example of having retained its original dynamism and excitement even for more than 80 years after its discovery. It has proved itself to be a rich field by continually offering frontal challenges in both research and applications. Indeed, one finds that a majority of internationally renowned condensed matter theorists, at some point of their career, have found excitement in working in this important area. Superconductivity presents a unique example of having fetched Nobel awards as many as four times to date, and yet, interestingly enough, the field still remains open for new insights and discoveries which could undeniably be of immense technological value. 1 fig

  20. Superconducting thin films of Bi-Sr-Ca-Cu-O by laser ablation

    International Nuclear Information System (INIS)

    Bedekar, M.M.

    1992-01-01

    The discovery of a new class of copper oxide superconductors has led to the development of three major systems that exhibit superconducting properties. The Bi-Sr-Ca-Cu-O superconductors offer intrinsic advantages due to the high T c , chemical inertness and tolerance for a range of compositions. However, thin film research on these materials has progressed more slowly than the other cuprate systems. This dissertation examines the film growth, by laser ablation, of the Bi-Sr-Ca-Cu-O superconductors and the effect of the deposition parameters such as the laser target interaction, substrate temperature, target to substrate distance, deposition and cooling pressure, target type and processing and the substrate type. CO 2 laser ablation was shown to give rise to a non-stoichiometric material transfer due to the low fluences and long pulse lengths. In situ superconducting thin films with T c(0) 's of 76 K could be deposited using the KrF laser at substrate temperatures of 5 degrees C to 20 degrees C below phases. Lower temperatures gave rise to a mixture of 2201 and glassy phases. An increase in the target to substrate distance led to a deterioration of the electrical and structural properties of the films due to a decrease in the energy for film formation. A maximum in T c(0) was observed at 450 mtorr as the deposition pressure was varied between 200 to 700 mtorr. Optimum oxygen incorporation could be achieved by cooling the films in high oxygen pressures and the best films were obtained with 700 torr cooling pressure. The oxygen deficiency of the hot pressed targets led to inferior properties compared to the conventionally sintered targets. The microwave surface resistance of the films measured at 35 GHz showed an onset at 80 K and dropped below that of copper at 30 K. The study of the laser ablation process in this system revealed the presence of a stoichiometric forward directed component and a diffuse evaporation component

  1. Upper critical magnetic field of superconducting films with magnetic impurities

    International Nuclear Information System (INIS)

    Lemberger, T.R.

    1978-01-01

    The upper critical magnetic field, H/sub c2/(T), of In-Mn and Pb-Mn alloy films was measured. H/sub c2/ was determined from the resistance of the films. The results were compared with the theory of Fulde and Maki. This theory assumes that the electron-phonon coupling is weak, and that the interaction between the impurity spins and the conduction electron spins is weak. The theory predicts that the pair-breaking effect of the magnetic impurities is temperature-independent, and that the pair-breaking effects of the magnetic impurities and the applied magnetic field are additive. Furthermore, it predicts explicitly the temperature dependence of H/sub c2/. The temperature dependence of H/sub c2/ for the In-Mn alloy films is well described by the Fulde-Maki theory, despite the moderately strong electron-phonon coupling and the strong interaction between the impurity spins and the conduction electron spins. The temperature dependence of H/sub c2/ for the Pb-Mn alloy films is not well described by the Fulde-Maki theory, probably due to the strong electron-phonon coupling in Pb. However, even without a quantitatively correct theory, one can conclude from the Pb-Mn data that the pair-breaking effect of the magnetic impurities is temperature independent, and that the pair-breaking effects of the magnetic impurities and the applied magnetic field are additive. For some of the Pb-Mn alloy films, there was a region of positive curvature in H/sub c2/(T) near the zero-field transition temperature. This positive curvature is not understood

  2. Superconductivity

    International Nuclear Information System (INIS)

    Anon.

    1988-01-01

    This book profiles the research activity of 42 companies in the superconductivity field, worldwide. It forms a unique and comprehensive directory to this emerging technology. For each research site, it details the various projects in progress, analyzes the level of activity, pinpoints applications and R and D areas, reviews strategies and provides complete contact information. It lists key individuals, offers international comparisons of government funding, reviews market forecasts and development timetables and features a bibliography of selected articles on the subject

  3. Microstructural and compositional analysis of YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} films grown by MOCVD before and after GCIB smoothing

    Energy Technology Data Exchange (ETDEWEB)

    Hatzistergos, M.S.; Efstathiadis, H.; Reeves, J.L.; Selvamanickam, V.; Allen, L.P.; Lifshin, E.; Haldar, P

    2004-06-15

    The microstructural and compositional evolution of thick (>1 {mu}m) high temperature superconducting YBa{sub 2}Cu{sub 3}O{sub 7-x} (YBCO) films grown on single crystal SrTiO{sub 3} substrates by the metal organic chemical vapor deposition (MOCVD) process was investigated by focused ion beam microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and atomic force microscopy. This study showed that as the MOCVD YBCO film thickness increased above 0.5 {mu}m, defects such as second phase particles, pores, and misaligned grains preferentially nucleated and grew at the YBCO surface. A portion of this defective top layer was eliminated from all the samples using a gas cluster ion beam (GCIB) process that first removed material with a focused argon cluster beam. Next, an oxygen cluster beam was used to smooth the surface and re-oxygenate the YBCO. Comparing the critical current (I{sub c}) measured before and after GCIB processing showed that the I{sub c} remained the same, and even improved, when part of the defective top layer was removed. This microstructural and electromagnetic 'dead layer' is believed to be responsible for the overall I{sub c} decrease of MOCVD YBCO films thicker than 0.5 {mu}m.

  4. Microstructural and compositional analysis of YBa2Cu3O7-δ films grown by MOCVD before and after GCIB smoothing

    International Nuclear Information System (INIS)

    Hatzistergos, M.S.; Efstathiadis, H.; Reeves, J.L.; Selvamanickam, V.; Allen, L.P.; Lifshin, E.; Haldar, P.

    2004-01-01

    The microstructural and compositional evolution of thick (>1 μm) high temperature superconducting YBa 2 Cu 3 O 7-x (YBCO) films grown on single crystal SrTiO 3 substrates by the metal organic chemical vapor deposition (MOCVD) process was investigated by focused ion beam microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and atomic force microscopy. This study showed that as the MOCVD YBCO film thickness increased above 0.5 μm, defects such as second phase particles, pores, and misaligned grains preferentially nucleated and grew at the YBCO surface. A portion of this defective top layer was eliminated from all the samples using a gas cluster ion beam (GCIB) process that first removed material with a focused argon cluster beam. Next, an oxygen cluster beam was used to smooth the surface and re-oxygenate the YBCO. Comparing the critical current (I c ) measured before and after GCIB processing showed that the I c remained the same, and even improved, when part of the defective top layer was removed. This microstructural and electromagnetic 'dead layer' is believed to be responsible for the overall I c decrease of MOCVD YBCO films thicker than 0.5 μm

  5. Superconductivity

    International Nuclear Information System (INIS)

    Buller, L.; Carrillo, F.; Dietert, R.; Kotziapashis, A.

    1989-01-01

    Superconductors are materials which combine the property of zero electric resistance with the capability to exclude any adjacent magnetic field. This leads to many large scale applications such as the much publicized levitating train, generation of magnetic fields in MHD electric generators, and special medical diagnostic equipment. On a smaller-scale, superconductive materials could replace existing resistive connectors and decrease signal delays by reducing the RLC time constants. Thus, a computer could operate at much higher speeds, and consequently at lower power levels which would reduce the need for heat removal and allow closer spacing of circuitry. Although technical advances and proposed applications are constantly being published, it should be recognized that superconductivity is a slowly developing technology. It has taken scientists almost eighty years to learn what they now know about this material and its function. The present paper provides an overview of the historical development of superconductivity and describes some of the potential applications for this new technology as it pertains to the electronics industry

  6. In-situ laser processing and microstructural characteristics of YBa2Cu3O7-δ thin films on Si with TiN buffer layer

    International Nuclear Information System (INIS)

    Tiwari, P.; Zheleva, T.; Narayan, J.

    1993-01-01

    The authors have prepared high-quality superconducting YBa 2 Cu 3 O 7 -δ (YBCO) thin films on Si(100) with TiN as a buffer layer using in-situ multitarget deposition system. Both TiN and YBCO thin films were deposited sequentially by KrF excimer laser ( | = 248 nm ) at substrate temperature of 650 C . Thin films were characterized using X-ray diffraction (XRD), four-point-probe ac resistivity, scanning electron microscopy (S E M), transmission electron microscopy (TEM), and Rutherford backscattering (RBS). The TiN buffer layer was epitaxial and the epitaxial relationship was found to be cube on cube with TiN parallel Si. YBCO thin films on Si with TiN buffer layer showed the transition temperature of 90-92K with T co (zero resistance temperature) of 84K. The authors have found that the quality of the buffer layer is very important in determining the superconducting transition temperature of the thin film. The effects of processing parameters and the correlation of microstructural features with superconducting properties are discussed in detail

  7. YBa{sub 2}Cu{sub 3}O{sub 7-x} thin films prepared by chemical solution deposition

    Energy Technology Data Exchange (ETDEWEB)

    Apetrii, Claudia

    2009-11-25

    The discovery of superconductivity in ceramic materials by Bednorz and Mueller in early 1987, immediately followed by Wu et al., who showed that YBa{sub 2}Cu{sub 3}O{sub 7-x} (YBCO) becomes superconducting (92 K) well above the boiling point of nitrogen (77 K) created a great excitement in superconductivity research. Potential applications of high T{sub c}-superconductors require large critical currents and high-applied magnetic fields. Effective ways to increase the critical current density at high magnetic fields in YBCO are the introduction of nanoparticles and chemical substitution of yttrium by other rare earth elements. Since low costs and environmental compatibility are essential conditions for the preparation of long length YBCO films, the cost effective chemical solution deposition (CSD) procedure was selected, given that no vacuum technology is required. To reveal the flexibility and the good optimization possibilities of the CSD approach two main processes were chosen for comparison: a fluorine-free method, namely the polymer-metal precursor technique, and a fluorine-based method, the metalorganic deposition (MOD) using the trifluoroacetates (TFA) technique. Sharp transition temperature widths {delta}T{sub c} of 1.1 K for the polymer metal method, 0.8 K for TFA method and critical current densities J{sub c} of {approx}3.5 MA/cm{sup 2} shows that high quality YBCO thin films can be produced using both techniques. Especially interesting is the magnetic field dependence of the critical current density J{sub c}(B) of the Y(Dy)BCO (80 %) films showing that for the lower magnetic fields the critical current density J{sub c}(B) is higher for a standard YBCO film, but at fields higher than 4.5 T the critical current density J{sub c}(B) of Y(Dy)BCO is larger than that for the YBCO. Above 8 T, J{sub c}(B) of the Y(Dy)BCO film is more than one order of magnitude higher than in pure YBCO film. (orig.)

  8. Thermal stability analysis of YBCO-coated conductors subject to over-currents

    Energy Technology Data Exchange (ETDEWEB)

    MartInez, E; Angurel, L A; Pelegrin, J [Instituto de Ciencia de Materiales de Aragon, CSIC-Universidad de Zaragoza, C/Maria de Luna 3, E-50018 Zaragoza (Spain); Xie, Y Y; Selvamanickam, V [SuperPower Incorporated, Schenectady, NY 12304 (United States)

    2010-02-15

    The thermal stability of superconducting YBCO-coated conductors subject to over-currents are analysed. We have studied the effect of DC and AC over-current pulses in Cu-stabilized and non-stabilized coated conductors by measuring the electric field and temperature profiles of these conductors immersed in liquid nitrogen. Current pulses of short duration of about 90 ms and long duration of a few seconds were applied to the samples. Three different cooling regimes of liquid nitrogen-convection, nucleate boiling and film boiling-were observed and their influence on the recovery time of superconductivity in the coated conductors after the over-current pulses has been analysed. We have studied the recovery behaviour under two different conditions, in which the current was set to zero and to the operating current after the current pulses. These experiments simulated the conditions during an over-current situation in different electric power applications with special attention given to the behaviour of these coated conductors acting as in-fault current limiters.

  9. Thermal stability analysis of YBCO-coated conductors subject to over-currents

    International Nuclear Information System (INIS)

    MartInez, E; Angurel, L A; Pelegrin, J; Xie, Y Y; Selvamanickam, V

    2010-01-01

    The thermal stability of superconducting YBCO-coated conductors subject to over-currents are analysed. We have studied the effect of DC and AC over-current pulses in Cu-stabilized and non-stabilized coated conductors by measuring the electric field and temperature profiles of these conductors immersed in liquid nitrogen. Current pulses of short duration of about 90 ms and long duration of a few seconds were applied to the samples. Three different cooling regimes of liquid nitrogen-convection, nucleate boiling and film boiling-were observed and their influence on the recovery time of superconductivity in the coated conductors after the over-current pulses has been analysed. We have studied the recovery behaviour under two different conditions, in which the current was set to zero and to the operating current after the current pulses. These experiments simulated the conditions during an over-current situation in different electric power applications with special attention given to the behaviour of these coated conductors acting as in-fault current limiters.

  10. Investigation of the epitaxial growth of Pb(Zr{sub 0,52}Ti{sub 0,48})O{sub 3} thin films and their application in ferroelectric superconducting field effect transistors; Untersuchung des epitaktischen Wachstums duenner Pb(Zr{sub 0,52}Ti{sub 0,48})O{sub 3}-Schichten und ihre Anwendung in ferroelektrischen supraleitenden Feldeffektransistoren

    Energy Technology Data Exchange (ETDEWEB)

    Aidam, R

    1999-02-01

    The influences of the polarization of ferroelectric Pb(Zr{sub 0.52}Ti{sub 0.48})O{sub 3} (PZT) films on the properties of YBa{sub 2}Cu{sub 3}O{sub x} (YBCO) films were investigated in ferroelectric superconducting field effect transistors (FSuFETs). First the epitaxial growth of PZT films deposited by reactive sputtering in an argon/oxygen atmosphere was investigated. SrTiO{sub 3} single crystals and YBCO thin films proved as suitable substrates. The lead content of the PZT films depended sensitively on the deposition temperature T{sub s} and the gas pressure. By using a high pressure of 0.26 mbar the correct stoichiometry could be achieved up to an maximum T{sub s} of 580 C. Above a minimum T{sub s} of 540 C the ferroelectric perovskite structure grew. In the optimum temperature range between 560 C and 580 C the films grew with a minimum mosaic spread of {delta}{omega} < 0.3 and a small amount of less than 1% of paraelectric phase. The best ferroelectric properties could be obtained for films with the highest degree of epitaxy and the correct stoichiometry. The maximum remanent polarization amounted P{sub r} = 61 {mu}C/cm{sup 2} and the coercive field E{sub C} was 150 kV/cm at 77 K. The breakdown field was four to five times larger than E{sub C}. Fatigue studies revealed a loss of switchable polarization of 30% after 10{sup 8} cycles at 77 K, whereas loss of retention and the effect of ageing were negligible. During the process of oxidation of the heterostructure at 400 C and an oxygen pressure of 800 mbar a reaction at the PZT/YBCO interface was observed, which lead to a degradation of the transport properties of the superconductor. This reaction could be avoided by a thin SrTiO{sub 3} buffer layer without disturbing the ferroelectric hysteresis essentially.

  11. Thin Film Technology of High-Critical-Temperature Superconducting Electronics.

    Science.gov (United States)

    1985-12-11

    ANALISIS OF THIN-FILM SUPERCONDUCTORS J. Talvacchio, M. A. Janocko, J. R. Gavaler, and A...in the areas of substrate preparation, niobum nitride, nlobium-tin, and molybdenum-rhenium. AN INTEGRATED DEPOSITION AND ANALISI - FACILITT The four...mobility low (64). The voids are separating 1-3 nm clusters of dense deposit. At low deposition temperatures this microstructure will persist near

  12. Fermion analogy for layered superconducting films in parallel magnetic field

    International Nuclear Information System (INIS)

    Rodriguez, J.P.

    1997-01-01

    The equivalence between the Lawrence-Doniach model for films of extreme type-II layered superconductors and a generalization of the back-scattering model for spin-(1/2) electrons in one dimension is demonstrated. This fermion analogy is then exploited to obtain an anomalous H parallel -1 tail for the parallel equilibrium magnetization of the minimal double-layer case in the limit of high parallel magnetic fields H parallel for temperatures in the critical regime. (orig.)

  13. LaNiO{sub 3} buffer layers for high critical current density YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} and Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub 8{minus}{delta}} films

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, C.M.; Parilla, P.A.; Siegal, M.P.; Ginley, D.S.; Wang, Y.; Blaugher, R.D.; Price, J.C.; Overmyer, D.L.; Venturini, E.L.

    1999-10-01

    We demonstrate high critical current density superconducting films of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} (YBCO) and Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub 8{minus}{delta}} (Tl-2212) using LaNiO{sub 3} (LNO) buffer layers. YBCO films grown on an LNO buffer layer have only a slightly lower J{sub c} (5 K, H=0) than films grown directly on a bare LaAlO{sub 3} substrate. YBCO films grown on LNO buffer layers exhibit minor microstructural disorder and enhanced flux pinning. LNO-buffered Tl-2212 samples show large reductions in J{sub c} at all temperatures and fields compared to those grown on bare LaAlO{sub 3}, correlating to both {ital a}-axis grain and nonsuperconducting phase formation. LNO could be a promising buffer layer for both YBCO and Tl-based superconducting films in coated conductor applications. {copyright} {ital 1999 American Institute of Physics.}

  14. Development of 1 m HTS conductor using YBCO on textured metal substrate

    International Nuclear Information System (INIS)

    Yagi, M.; Sakamoto, H.; Mukoyama, S.; Yamamoto, K.; Amemiya, N.; Nagaya, S.; Kashima, N.; Shiohara, Y.

    2009-01-01

    We fabricated 1 m high temperature superconducting conductor (HTS conductor) using YBa 2 Cu 3 O 7-x coated conductors (YBCO tapes) on textured metal substrates, which are expected to be lower in cost than YBCO tapes using ion-beam assisted deposition. Those substrate and intermediate layers were manufactured by Furukawa Electric, and YBCO and a protective layer were applied to the intermediate layer by Chubu Electric Power. Before fabricating the conductor, a 0.1 mm thick copper tape was soldered to the YBCO tape, and 10 mm wide YBCO tape was divided into three strips by a YAG laser. To have sufficient current capacity for 1 kA, a two-layer conductor was fabricated, and its critical current (I c ) was 1976 A, but the magnetic properties of the textured metal substrates affected the increase in AC loss. In a low current region, the AC loss in this conductor was much higher than the Norris strip model, but approached the Norris strip model in the high current region because the magnetization was almost saturated. Low AC loss of 0.144 W/m at 1 kA rms was achieved even though the conductor had a small outer diameter of 20 mm and was composed of YBCO tapes with magnetic substrates.

  15. Probing the local microwave properties of superconducting thin films by a scanning microwave near-field microscope

    CERN Document Server

    Wu, L Y; Wang, K L; Jiang, T; Kang, L; Yang, S Z; Wu, P H

    2002-01-01

    In this paper, we present our approach to probe the local microwave properties of superconducting thin films by using the microwave near-field scanning technique. We have employed a coaxial cavity together with a niobium tip as the probe and established a scanning sample stage cooled by liquid nitrogen to study thin film devices at low temperature in our scanning microwave near-field microscope. Nondestructive images have been obtained on the inhomogeneity of the YBaCuO superconducting thin films at microwave frequency. We believe that these results would be helpful in evaluating the microwave performance of the devices.

  16. Measurement of the magnetic penetration depth in p-doped superconducting diamond films

    Energy Technology Data Exchange (ETDEWEB)

    Fuchs, Lorenz; Brunner, Markus C.P.; Schneider, Ina; Kronfeldner, Klaus [University of Regensburg (Germany); Bousquet, Jessica; Bustarret, Etienne; Strunk, Christoph [Institut Neel, Grenoble (France)

    2016-07-01

    Boron-doped diamond becomes superconducting once a critical doping concentration of 4.5 x 10{sup 20} cm{sup -3} is reached. Mutual inductance measurements with a two-coil setup have been performed to determine the magnetic penetration depth λ(T), which is a measure for the superfluid stiffnes θ ∝ 1/λ{sup 2}(T). Two superconducting p-doped diamond films with thicknesses of 145 nm and 345 nm were investigated. At low temperatures these values agree reasonably with the values expected within BCS-theory using T{sub c}, carrier density and mean free path determined from electric transport measurements. Magnetic penetration depths of 3.7 μm for the thinner and 2.6 μm for the thicker film have been found. λ decreases and accordingly θ increases with increasing film thickness. On the other hand, the superfluid stiffness drops by a factor of 2 or even more at T{sub c}/2, i.e., much faster than expected from BCS-theory, but remains finite between T{sub c}/2 < T < T{sub c}. At present it is unclear, whether this behavior results from the proliferation of phase fluctuations already far below T{sub c} or from a spatial inhomogeneity of the films.

  17. Niobium thin film deposition studies on copper surfaces for superconducting radio frequency cavity applications

    Directory of Open Access Journals (Sweden)

    W. M. Roach

    2012-06-01

    Full Text Available Thin film coatings have the potential to increase both the thermal efficiency and accelerating gradient in superconducting radio frequency accelerator cavities. However, before this potential can be realized, systematic studies on structure-property correlations in these thin films need to be carried out since the reduced geometry, combined with specific growth parameters, can modify the physical properties of the materials when compared to their bulk form. Here, we present our systematic studies of Nb thin films deposited onto Cu surfaces to clarify possible reasons for the limited success that this process exhibited in previous attempts. We compare these films with Nb grown on other surfaces. In particular, we study the crystal structure and surface morphology and their effect on superconducting properties, such as critical temperature and lower critical field. We found that higher deposition temperature leads to a sharper critical temperature transition, but also to increased roughness indicating that there are competing mechanisms that must be considered for further optimization.

  18. Origin of photovoltaic effect in superconducting YBa2Cu3O6.96 ceramics

    Science.gov (United States)

    Yang, F.; Han, M. Y.; Chang, F. G.

    2015-01-01

    We report remarkable photovoltaic effect in YBa2Cu3O6.96 (YBCO) ceramic between 50 and 300 K induced by blue-laser illumination, which is directly related to the superconductivity of YBCO and the YBCO-metallic electrode interface. There is a polarity reversal for the open circuit voltage Voc and short circuit current Isc when YBCO undergoes a transition from superconducting to resistive state. We show that there exists an electrical potential across the superconductor-normal metal interface, which provides the separation force for the photo-induced electron-hole pairs. This interface potential directs from YBCO to the metal electrode when YBCO is superconducting and switches to the opposite direction when YBCO becomes nonsuperconducting. The origin of the potential may be readily associated with the proximity effect at metal-superconductor interface when YBCO is superconducting and its value is estimated to be ~10–8 mV at 50 K with a laser intensity of 502 mW/cm2. Combination of a p-type material YBCO at normal state with an n-type material Ag-paste forms a quasi-pn junction which is responsible for the photovoltaic behavior of YBCO ceramics at high temperatures. Our findings may pave the way to new applications of photon-electronic devices and shed further light on the proximity effect at the superconductor-metal interface. PMID:26099727

  19. Superconductivity in transparent zinc-doped In2O3 films having low carrier density

    Directory of Open Access Journals (Sweden)

    Kazumasa Makise, Nobuhito Kokubo, Satoshi Takada, Takashi Yamaguti, Syunsuke Ogura, Kazumasa Yamada, Bunjyu Shinozaki, Koki Yano, Kazuyoshi Inoue and Hiroaki Nakamura

    2008-01-01

    Full Text Available Thin polycrystalline zinc-doped indium oxide (In2O3–ZnO films were prepared by post-annealing amorphous films with various weight concentrations x of ZnO in the range 0≤x ≤0.06. We have studied the dependences of the resistivity ρ and Hall coefficient on temperature T and magnetic field H in the range 0.5≤T ≤300 K, H≤6 Tfor 350 nm films annealed in air. Films with 0≤x≤0.03 show the superconducting resistive transition. The transition temperature Tc is below 3.3 K and the carrier density n is about 1025–1026 m−3. The annealed In2O3–ZnO films were examined by transmission electron microscopy and x-ray diffraction analysis revealing that the crystallinity of the films depends on the annealing time. We studied the upper critical magnetic field Hc2 (T for the film with x = 0.01. From the slope of dHc2 /dT, we obtain the coherence length ξ (0 ≈ 10 nm at T = 0 K and a coefficient of electronic heat capacity that is small compared with those of other oxide materials.

  20. Characterization of the microwave properties of superconducting films with high transition temperature

    International Nuclear Information System (INIS)

    Richter, W.; Klinger, M.; Daginnus, M.

    1989-01-01

    In the meantime high quality Y-Ba-Cu-O thin films were produced. The latest results show, that its surface resistances are clearly lower than the values of copper, measured at a temperature of 77 K and up to frequencies of 86 GHz. This examination had the aim to produce high-T c films with a simple and low cost method, to use them as transmission lines at frequencies up to 30 GHz and above. A screen printing process was investigated, and high-T c thick films were fabricated on several substrates. Superconducting transition temperatures up to 80 K (dc zero resistance) were obtained. The films showed no complete magnetic shielding, and its microwave surface resistances were clearly higher than that ones for copper. The a. c. Josephson effect was proved with granular structures of bulk Y-Ba-Cu-O material and with screen printed thick films. Because of its high surface resistances, these thick films are unsuitable for the use as transmission lines at high frequencies. However, the a.c. Josephson effect can be used to manufacture microwave sensors in bulk Y-Ba-Cu-O and screen printed films of Y-Ba-Cu-O, which have a favourable geometric structure. (orig.) With 16 refs., 2 tabs., 24 figs [de

  1. Superconducting (YBa2Cu3O7-δ) and manganite (La0.7Sr0.3MnO3) oxide thin film based devices

    International Nuclear Information System (INIS)

    Mechin, Laurence

    2005-01-01

    This manuscript presents my research activity since my PhD thesis defended in 1993. I mainly worked on two types of oxides: YBCO et LSMO. I always kept in mind the development of devices as a whole, i.e. from the thin film to the device characterization. One part of my work has been devoted to the study of structural, electrical or magnetic properties of the thin films in order to optimize deposition conditions. Both YBCO and LSMO oxides present a perovskite structure and require similar deposition conditions (700 - 750 C in O 2 pressure). I used three deposition methods: pulsed laser deposition, on axis high pressure sputtering and RF off axis sputtering. (author)

  2. Development of YBCO Superconductor for Electric Systems: Cooperative Research and Development Final Report, CRADA Number CRD-04-150

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharya, R.

    2013-03-01

    The proposed project will be collaborative in exploration of high temperature superconductor oxide films between SuperPower, Inc. and the National Renewable Energy Laboratory. This CRADA will attempt to develop YBCO based high temperature oxide technology.

  3. PBCO/YBCO bilayer growth and optimization for the fabrication of buffered step-edge Josephson junctions

    CSIR Research Space (South Africa)

    Van Staden, WF

    2009-04-01

    Full Text Available Bilayers of PBCO and YBCO are grown epitaxially on MgO substrates using PLD. In this paper, researchers discuss the entire optimization process in detail, giving quantitative parameter values. Film characterization included XRD, AFM and susceptance...

  4. Bibliography of high-T/sub c/ superconducting films

    International Nuclear Information System (INIS)

    Talvacchio, J.

    1989-01-01

    This document represents an effort to make bibliographic information on high-T/sub c/ superconductor films available to those who cannot access the on-line database at the Westinghouse R and D Center. The database contains a growing list of references -- approaching 5000 -- each of which is identified by a set of two-letter keywords. The database is used the same way as as INSPEC's, but its fixed set of standard keywords enables the user to obtain a complete list of references on keyworded topics. Since a single keyword (or search term) such as ''sputtering'' creates a bibliography that is too long for practical use, the database is used most effectively by combining a series of keywords using Boolean algebra to identify a handful of relevant references. The structure of this document is intended to present the subset of papers concerning high-T/sub c/ films (725 papers) in a compact format as a substitute for on-line searches. Rather than listing separate bibliographies for each of the 185 keywords, a single list of all the references is contained in Section 6, and indices based on the keywords are contained in Sections 3--5. This report is a true bibliography and does not contain any informative text. 725 refs

  5. The effects of Fe2O3 nanoparticles on MgB2 superconducting thin films

    International Nuclear Information System (INIS)

    Koparan, E.T.; Sidorenko, A.; Yanmaz, E.

    2013-01-01

    Full text: Since the discovery of superconductivity in binary MgB 2 compounds, extensive studies have been carried out because of its excellent properties for technological applications, such as high transition temperature (T c = 39 K), high upper critical field (H c2 ), high critical current density (J c ). Thin films are important for fundamental research as well as technological applications of any functional materials. Technological applications primarily depend on critical current density. The strong field dependence of J c for MgB 2 necessitates an enhancement in flux pinning performance in order to improve values in high magnetic fields. An effective way to improve the flux pinning is to introduce flux pinning centers into MgB 2 through a dopant having size comparable to the coherence length of MgB 2 . In this study, MgB 2 film with a thickness of about 600 nm was deposited on the MgO (100) single crystal substrate using a 'two-step' synthesis technique. Firstly, deposition of boron thin film was carried out by rf magnetron sputtering on MgO substrates and followed by a post deposition annealing at 850 degrees Celsius in magnesium vapour. In order to investigate the effect of Fe 2 O 3 nanoparticles on the structural and magnetic properties of films, MgB 2 films were coated with different concentrations of Fe 2 O 3 nanoparticles by a spin coating process. The effects of different concentrations of ferromagnetic Fe 2 O 3 nanoparticles on superconducting properties of obtained films were carried out by using structural (XRD, SEM, AFM), electrical (R-T) and magnetization (M-H, M-T and AC Susceptibility) measurements. It was calculated that anisotropic coefficient was about γ = 1.2 and coherence length of 5 nm for the uncoated film. As a result of coherence length, the appropriate diameters of Fe 2 O 3 nanoparticles were found to be 10 nm, indicating that these nanoparticles served as the pinning centers. Based on the data obtained from this study, it can be

  6. Fiber optic quench detection via optimized Rayleigh Scattering in high-field YBCO accelerator magnets

    Energy Technology Data Exchange (ETDEWEB)

    Flanagan, Gene [North Carolina State Univ., Raleigh, NC (United States)

    2016-02-17

    Yttrium barium copper oxide (YBCO) coated conductors are known for their ability to operate in the superconducting state at relatively high temperatures, even above the boiling point of liquid nitrogen (77 K). When these same conductors are operated at lower temperatures, they are able to operate in much higher magnetic fields than traditional superconductors like NiTi or Nb3Sn. Thus, YBCO superconducting magnets are one of the primary options for generating the high magnetic fields needed for future high energy physics devices. Due to slow quench propagation, quench detection remains one of the primary limitations to YBCO magnets. Fiber optic sensing, based upon Rayleigh scattering, has the potential for spatial resolution approaching the wavelength of light, or very fast temporal resolution at low spatial resolution, and a continuum of combinations in between. This project has studied, theoretically and experimentally, YBCO magnets and Rayleigh scattering quench detection systems to demonstrate feasibility of the systems for YBCO quench protection systems. Under this grant an experimentally validated 3D quench propagation model was used to accurately define the acceptable range of spatial and temporal resolutions for effective quench detection in YBCO magnets and to evaluate present-day and potentially improved YBCO conductors. The data volume and speed requirements for quench detection via Rayleigh scattering required the development of a high performance fiber optic based quench detection/data acquisition system and its integration with an existing voltage tap/thermo-couple based system. In this project, optical fibers are tightly co-wound into YBCO magnet coils, with the fiber on top of the conductor as turn-to-turn insulation. Local changes in the temperature or strain of the conductor are sensed by the optical fiber, which is in close thermal and mechanical contact with the conductor. Intrinsic imperfections in the fiber reflect Rayleigh

  7. Compositional analysis of YBaCuO superconducting films with ion beam analysis techniques

    International Nuclear Information System (INIS)

    Jones, S.; Timmers, H.; Ophel, T.R.; Elliman, R.G.

    1999-01-01

    High-T c YBa x Cu y O 7-δ superconducting films are being developed for applications such as superconducting quantum interference devices. The carrier concentration, critical current density J c and critical temperature T c of these films depend sensitively on the oxygen content . Stoichiometry, uniformity with depth, homogeneity across the sample and film thickness are also important quantities for their characterisation. It has been shown, for example, that the stoichiometry of the metallic elements affects the growth characteristics and surface morphology of the films. With the deposit ion techniques used, reproducibility of film properties is difficult. The characterisation of YBa x Cu y O 7-δ films with ion beam analysis techniques is complex. Whereas the three metallic elements can be detected with helium beams and Rutherford Backscattering (RBS), the oxygen signal is generally obscured by that from substrate elements. It can be better detected using resonant backscattering with 3.04MeV 4 He ions or nuclear reaction analysis. Elastic Recoil Detection (ERD) with high-energetic (1MeV/amu), heavy beams (Z > 120), enables all elements to be detected and separated in a single experiment. It is well established that ion bombardment induces vacancies in the oxygen sub-lattice, driving the material to change from crystalline to amorphous, the latter phase having a reduced oxygen content. In previous heavy ion ERD measurements of YBa x Cu yO z films with 200MeV 127 I beams, the opaque films became transparent in the beam spot area, indicative of the amorphous phase. The accuracy of the oxygen measurement is therefore questionable. Indeed, using Raman spectroscopy, distortions of the crystalline structure above a fluence of 5 x 10 11 ion/cm 2 and for higher doses some signatures of a reduction in oxygen content have been observed for such beams. It appears therefore that a correct determination of the oxygen content requires either a drastic reduction in fluence or a

  8. Electron scattering rate in epitaxial YBa2Cu3O7 superconducting films

    Science.gov (United States)

    Flik, M. I.; Zhang, Z. M.; Goodson, K. E.; Siegal, M. P.; Phillips, Julia M.

    1992-09-01

    This work determines the electron scattering rate in the a-b plane of epitaxial YBa2Cu3O7 films using two techniques. Infrared spectroscopy yields the scattering rate at temperatures of 10, 78, and 300 K by fitting reflectance data using thin-film optics and a model for the free-carrier conductivity. The scattering rate is also obtained using kinetic theory and an extrapolation of normal-state electrical resistivity data to superconducting temperatures based on the Bloch theory for the phonon-limited electrical resistivity of metals. The scattering rates determined using both techniques are in agreement and show that the electron mean free path in the a-b plane of YBa2Cu3O7 superconducting films is three to four times the coherence length. Hence YBa2Cu3O7 is pure but not in the extreme pure limit. An average defect interaction range of 4 nm is obtained using the defect density resulting from flux-pinning considerations.

  9. Niobium Nitride Thin Films and Multilayers for Superconducting Radio Frequency Cavities

    Science.gov (United States)

    Roach, William; Beringer, Douglas; Li, Zhaozhu; Clavero, Cesar; Lukaszew, Rosa

    2013-03-01

    Niobium nitride in thin film form has been considered for a number of applications including multi-layered coatings onto superconducting radio frequency cavities which have been proposed to overcome the fundamental accelerating gradient limit of ~50 MV/m in niobium based accelerators. In order to fulfill the latter application, the selected superconductor's thermodynamic critical field, HC, must be larger than that of niobium and separated from the Nb surface by an insulating layer in order to shield the Nb cavity from field penetration and thus allow higher field gradients. Thus, for the successful implementation of such multilayered stack it is important to consider not just the materials inherent properties but also how these properties may be affected in thin film geometry and also by the specific deposition techniques used. Here, we show the results of our correlated study of structure and superconducting properties in niobium nitride thin films and discuss the shielding exhibited in NbN/MgO/Nb multilayer samples beyond the lower critical field of Nb for the first time. This work was funded by the Defense Threat Reduction Agency (HDTRA-10-1-0072).

  10. Magnetic force acting on a magnetic dipole over a superconducting thin film

    International Nuclear Information System (INIS)

    Wei, J.C.; Chen, J.L.; Horng, L.; Yang, T.J.

    1996-01-01

    The magnetostatic interaction energy and corresponding magnetic force acting on a magnetic point dipole placed above a type-II thin superconducting film in the mixed state with a single vortex are calculated using electromagnetics coupled with the London theory of superconductivity. If a vortex is trapped by a circular defect of radius b 1, where a is the separation between the dipole and the thin film, the only difference between two results is in the cutoff length, i.e., in the case of a circular defect the only difference in the critical position calculation is the cutoff at radius b rather than at coherence length ξ. The pinning force of a single vortex by a circular defect is also calculated. Further, we investigate the conditions of the vortex creation for various cases (including the first, second, and third vortices) for a free of pinning center in the examining region. It is found that the creation of a new single vortex in the thin film causes an abrupt change in vertical levitation force: the force changed discontinuously. copyright 1996 The American Physical Society

  11. Reactive diffusion and superconductivity of Nb3Al multilayer films

    International Nuclear Information System (INIS)

    Vandenberg, J.M.; Hong, M.; Hamm, R.A.; Gurvitch, M.

    1985-01-01

    Thin films of A15 Nb 3 Al have been prepared by reactive diffusion of sputter-deposited Nb/Al multilayers. The diffusion reactions were studied by in situ annealing x-ray diffraction in the temperature range 50--950 0 C. Initially the Nb and Al sublayers react to form the phase NbAl 3 . This interface reaction prevents the formation of the sigma-phase Nb 2 Al, frequently found as a second phase in A15 Nb 3 Al materials; NbAl 3 reacts with the remaining Nb to form the A15 phase. The highest T/sub c/, 16.2 K measured resistively and 15.2 K inductively, was found in a Nb/Al multilayer with an A15 cell parameter a 0 = 5.195 A which corresponds to approx.20 at. % Al. From a comparison with previous investigations of the T/sub c/ dependence on Al concentration and A15 cell parameter, it is concluded that a small amount of the A15 phase has a higher composition of 22--23 at. % Al

  12. Superconductivity in Na{sub 1-x}CoO{sub 2}.yH{sub 2}O thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hildebrandt, Sandra; Komissinkiy, Philipp; Alff, Lambert [Institute for Materials Science, TU Darmstadt (Germany); Fritsch, Ingo; Habermeier, Hanns-Ulrich [Max-Planck-Institute for Solid State Research, Stuttgart (Germany); Lemmens, Peter [Institute for Condensed Matter Physics, TU Braunschweig (Germany)

    2010-07-01

    Sodium cobaltate (Na{sub 1-x}CoO{sub 2}) is a novel material with thermoelectric behavior, charge and spin ordered states dependent on the sodium content in the composition. A superconducting phase was found in water intercalated sodium cobaltate (Na{sub 1-x}CoO{sub 2}.yH{sub 2}O) with x=0.65-0.7 and y=0.9-1.3. The pairing state is still under debate, but there are some indications for a spin-triplet or p-wave superconducting pairing state. First films of Na{sub 1-x}CoO{sub 2}.yH{sub 2}O with a superconducting transition temperature near 5 K have been successfully grown. Here we report on thin films of Na{sub 1-x}CoO{sub 2} grown by pulsed laser deposition technique. The deposition parameters, sodium deintercalation and water intercalation conditions are tuned in order to obtain the superconducting phase. The instability of this phase might be an indication for triplet superconductivity, which is known to be affected strongly by impurities and defects.This observation is in agreement with the fact that so far also no superconducting thin films of the most famous triplet superconductor Sr{sub 2}RuO{sub 4} have been reported.

  13. Equilibrium vortex structures of type-II/1 superconducting films with washboard pinning landscapes

    Science.gov (United States)

    Wei, C. A.; Xu, X. B.; Xu, X. N.; Wang, Z. H.; Gu, M.

    2018-05-01

    We numerically study the equilibrium vortex structures of type-II/1 superconducting films with a periodic quasi-one-dimensional corrugated substrate. We show as a function of substrate period and pinning strength that, the vortex system displays a variety of vortex phases including arrays consisted of vortex clumps with different morphologies, ordered vortex stripes parallel and perpendicular to pinning troughs, and ordered one-dimensional vortex chains. Our simulations are helpful in understanding the structural modulations for extensive systems with both competing interactions and competing periodicities.

  14. Energy gap and surface structure of superconducting diamond films probed by scanning tunneling microscopy

    International Nuclear Information System (INIS)

    Nishizaki, Terukazu; Takano, Yoshihiko; Nagao, Masanori; Takenouchi, Tomohiro; Kawarada, Hiroshi; Kobayashi, Norio

    2007-01-01

    We have performed scanning tunneling microscopy/spectroscopy (STM/STS) experiments on (1 1 1)-oriented epitaxial films of heavily boron-doped diamond at T = 0.47 K. The STM topography shows two kinds of atomic structures: a hydrogenated 1 x 1 structure, C(1 1 1)1 x 1:H, and an amorphous structure. On the C(1 1 1)1 x 1:H region, the tunneling spectra show superconducting property with the energy gap Δ = 0.83 meV. The obtained gap ratio 2Δ/k B T c = 3.57 is consistent with the weak-coupling BCS theory

  15. Commensurate vortex configurations in thin superconducting films nanostructured by square lattice of magnetic dots

    Energy Technology Data Exchange (ETDEWEB)

    Milosevic, M.V.; Peeters, F.M

    2004-05-01

    Within the phenomenological Ginzburg-Landau (GL) theory, we investigate the vortex structure of a thin superconducting film (SC) with a regular matrix of ferromagnetic dots (FD) deposited on top of it. The vortex pinning properties of such a magnetic lattice are studied, and the field polarity dependent votex pinning is observed. The exact vortex configuration depends on the size of the magnetic dots, their polarity, periodicity of the FD-rooster and the properties of the SC expressed through the effective Ginzburg-Landau parameter {kappa}*.

  16. Commensurate vortex configurations in thin superconducting films nanostructured by square lattice of magnetic dots

    International Nuclear Information System (INIS)

    Milosevic, M.V.; Peeters, F.M.

    2004-01-01

    Within the phenomenological Ginzburg-Landau (GL) theory, we investigate the vortex structure of a thin superconducting film (SC) with a regular matrix of ferromagnetic dots (FD) deposited on top of it. The vortex pinning properties of such a magnetic lattice are studied, and the field polarity dependent votex pinning is observed. The exact vortex configuration depends on the size of the magnetic dots, their polarity, periodicity of the FD-rooster and the properties of the SC expressed through the effective Ginzburg-Landau parameter κ*

  17. Critical region of a type II superconducting film near Hsub(c2): rational approximants

    International Nuclear Information System (INIS)

    Ruggeri, G.J.

    1979-01-01

    The high-temperature perturbative expansions for the thermal quantities of a type II superconducting film are extrapolated to the critical region near Hsub(c2) by means of new rational approximants of the Pade type. The new approximants are forced to reproduce the leading correction to the flux lattice contribution on the low-temperature side of the transition. Compared to those previously considered in the literature: (i) the mutual consistency of the approximants is improved; and (ii) they are nearer to the exact solution of the zero-dimensional Landau-Ginsburg model. (author)

  18. Growth of epitaxial Ba2YCu3O(7-delta) thin films and control of their superconducting properties

    International Nuclear Information System (INIS)

    Siegal, M.P.; Phillips, J.M.

    1992-01-01

    The relationship is experimentally defined between the superconducting behavior of Ba2YCu3O(7-delta) (BYCO) films and their structural characteristics. The BYCO films are grown on LaAlO3 100-plane by coevaporating BaF2, Y, and Cu followed by ex situ annealing, and the crystalline quality is tested by Rutherford backscattering ion channeling. SEM is employed to study film morphology, and several techniques are used to measure the transition temperature (Tc), critical current density (Jc), and the penetration length. It is found that point defects and dislocations decrease as the high-temperature stage (Ta) increases; crevices, pinholes, and microcracks are also noted which are related to specific values of Tc, Ta, and penetration length. The results of the present experiments indicate that the material properties of superconducting materials should be examined closely to distinguish between pure superconducting behavior and characteristics related to material structure. 21 refs

  19. Levitation force of melt-textured YBCO superconductors under non-quasi-static situation

    Science.gov (United States)

    Zhao, Z. M.; Xu, J. M.; Yuan, X. Y.; Zhang, C. P.

    2018-06-01

    The superconducting levitation force of a simple superconductor-magnet system under non-quasi-static situation is investigated experimentally. Two yttrium barium copper oxide (YBCO) samples with different performances are chosen from two small batches of samples prepared by the top-seeded melt-textured growth process. The residual carbon content of the precursor powders of the two batches is different due to different heat treatment processes. During the experimental process for measuring the levitation force, the value of the relative speed between the YBCO sample and the permanent magnet is higher than that in conventional studies. The variation characteristics of the superconducting levitation force are analyzed and a crossing phenomenon in the force-displacement hysteresis curves is observed. The results indicate that the superconducting levitation force is different due to the different residual carbon contents. As residual carbon contents reduce, the crossing phenomenon is more obvious accordingly.

  20. Effects of argon implantation and vacuum annealing of the superconducting properties of single-crystal niobium films

    International Nuclear Information System (INIS)

    Zakirov, R.M.; Kuznetsov, V.P.; Shermergor, T.D.

    1980-01-01

    Characteristics of superconducting transition (Tsub(K), Hsub(perpendicular)) of monocrystalline niobium films on sapphire, irradiated by 35 keV Ar ions within 0.62x10 15 -5.6x10 16 ion/cm 2 dose range, are investigated. Introduction of argon atoms results in Tsub(K) decrease of films and rhosub(n), Hsub(perpendicular 0) and dHsub(perpendicular)/dT increase due to reduction of free path length of electrons. Shown is an essential difference in the behaviour of superconducting parameters of irradiated monocrystalline niobium films and films with niobium, dassol ved in the niobium lattice. Introduction of oxygen has been carried out by annealing of films in vacuum after their heating in the air

  1. Characterization of 3-dimensional superconductive thin film components for gravitational experiments in space

    Energy Technology Data Exchange (ETDEWEB)

    Hechler, S.; Nawrodt, R.; Nietzsche, S.; Vodel, W.; Seidel, P. [Friedrich-Schiller-Univ. Jena (Germany). Inst. fuer Festkoerperphysik; Dittus, H. [ZARM, Univ. Bremen (Germany); Loeffler, F. [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany)

    2007-07-01

    Superconducting quantum interference devices (SQUIDs) are used for high precise gravitational experiments. One of the most impressive experiments is the satellite test of the equivalence principle (STEP) of NASA/ESA. The STEP mission aims to prove a possible violation of Einstein's equivalence principle at an extreme level of accuracy of 1 part in 10{sup 18} in space. In this contribution we present an automatically working measurement equipment to characterize 3-dimensional superconducting thin film components like i.e. pick-up coils and test masses for STEP. The characterization is done by measurements of the transition temperature between the normal and the superconducting state using a special built anti-cryostat. Above all the setup was designed for use in normal LHe transport Dewars. The sample chamber has a volume of 150 cm{sup 3} and can be fully temperature controlled over a range from 4.2 K to 300 K with a resolution of better then 100 mK. (orig.)

  2. Application of a phenomenological model for the surface impedance in high temperature superconducting films

    International Nuclear Information System (INIS)

    Mosquera, A.S.; Landinez Tellez, D.A.; Roa-Rojas, J.

    2007-01-01

    We report the application of a phenomenological model for the microwave surface impedance in high temperature superconducting films. This model is based on the modified two-fluid model, in which the real and imaginary parts of the surface impedance use the modelling parameter γ. This is responsible for the superconducting and normal charge carrier density and is used for the description of the temperature dependence of the London penetration depth λ L (T) including λ L (0). The relaxation time model also uses the γ parameter in combination with the residual resistance parameter α. The parameter δ 1 1 , γ, α, and δ 2 . The parameter δ 2 n (T) is a result of the competition between the increase of the relaxation time and the decrease of the normal charge-carrier density. We applied this model to analyze experimental results of MgB 2 , YBa 2 Cu 3 O 7-δ and GdBa 2 Cu 3 O 7-δ superconducting material. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Angular dependence of the irreversible magnetization of YBa2Cu3O7 superconducting thin films

    International Nuclear Information System (INIS)

    Thrane, B.P.; Schlenker, C.; Dumas, J.; Buder, R.

    1996-01-01

    YBa 2 Cu 3 O 7 superconducting thin films have been studied by magnetization measurements in oblique fields up to 0.8 T both at low temperature and at temperatures close to T c . Both components of magnetization parallel and perpendicular to the applied field could be measured with two pairs of crossed detection coils. In all cases the magnetization is found to be perpendicular to the film plane. This is due to the self-field effects related to the thin-film geometry which force the critical currents to circulate along the film plane. At low temperature the properties are found to depend only on the component of the applied magnetic field perpendicular to this plane, as expected in the situation where demagnetizing field effects are dominant. However, at temperatures close to T c the critical currents and therefore the pinning are found to increase when the applied field approaches the film plane. This is attributed to the effect of intrinsic pinning which may be related to the kink structure of the vortices in oblique fields. copyright 1996 The American Physical Society

  4. Construction of sputtering system and preparation of high temperature superconducting thin films

    International Nuclear Information System (INIS)

    Kaynak, E.

    2000-01-01

    The preparation of high T c superconducting thin film is important both for the understanding of fundamental behaviours of these materials and for the investigations on the usefulness of technological applications. High quality thin films can be prepared by various kinds of techniques being used today. Among these, sputtering is the most preferred one. The primary aim of this work is the construction of a r. f. and c. magnetron sputtering system. For this goal, a magnetron sputtering system was designed and constructed having powers up to 500W (r.f.) and 1KW (d.c.) that enables to deposit thin films of various kinds of materials: metals, ceramics and magnetic materials. The temperature dependence of the electrical resistance of the films was investigated by using four-point probe method. The zero resistance and the transition with of the films were measured as 80-85 K, and 2-9 K, respectively. The A.C. susceptibility experiments were done by utilising the system that was designed and constructed. The applied field dependence of the real and imaginary components of the susceptibility that were measured between the 77-120 K temperature interval and at a fixed frequency was investigated

  5. A low energy muon spin rotation and point contact tunneling study of niobium films prepared for superconducting cavities

    Science.gov (United States)

    Junginger, Tobias; Calatroni, S.; Sublet, A.; Terenziani, G.; Prokscha, T.; Salman, Z.; Suter, A.; Proslier, T.; Zasadzinski, J.

    2017-12-01

    Point contact tunneling and low energy muon spin rotation are used to probe, on the same samples, the surface superconducting properties of micrometer thick niobium films deposited onto copper substrates using different sputtering techniques: diode, dc magnetron and HIPIMS. The combined results are compared to radio-frequency tests performances of RF cavities made with the same processes. Degraded surface superconducting properties are found to correlate to lower quality factors and stronger Q-slope. In addition, both techniques find evidence for surface paramagnetism on all samples and particularly on Nb films prepared by HIPIMS.

  6. A rapid process of Yba2Cu3O7-δ thin film fabrication using trifluoroacetate metal-organic deposition with polyethylene glycol additive

    DEFF Research Database (Denmark)

    Wu, Wei; Feng, Feng; Shi, Kai

    2013-01-01

    Trifluoroacetate metal-organic deposition (TFA-MOD) is a promising technique to fabricate YBa2Cu3O7-δ (YBCO) superconducting films. However, its slow pyrolysis process, which usually takes more than 10 h, constitutes a barrier for industrial production. In this study, polyethylene glycol (PEG......) was utilized to reduce the stress generation inside the coated films when the strong pyrolysis reactions happen. With the addition of 30 wt% PEG2000 to the precursor solution, a smooth film surface could be obtained through a rapid pyrolysis process of 15 min. After the optimizations of the crystallization...... and oxygenation processes, mass percentage and molecular weight of PEG additive, YBCO thin films with Jc of about 4.5 MA cm-2 (77 K, self-field) could be routinely fabricated using (20-30) wt% PEG(1000-2000) additive with a total treatment time of about 2 h including the 15 min pyrolysis process time. The effects...

  7. Superconducting Bi-Sr-Ca-Cu-O thin films from metallo-organic complexes

    International Nuclear Information System (INIS)

    Gruber, H.; Krautz, E.; Fritzer, H.P.; Popitsch, A.

    1991-01-01

    Thin films in the Bi-Sr-Ca-Cu-O system are produced by decomposition of organic precursor compounds containing different metallo-organic complexes. The superconducting phase identified is Bi 2 Sr 2 CaCu 2 O 8+x on (100)-MgO single crystal substrates, polycrystalline Au- and Ag-ribbons and Bi 2 Sr 2 Ca 2 Cu 3 O 10+x on Ag-ribbons. For the 2212-phase a zero resistance temperature of 79 K is found. The 2223-samples on Ag-ribbons show a broad transition at 110 K with a zero resistance at 85 K. SEM and EDX are used for the detection of the microstructure and composition of the prepared films. (orig.)

  8. Magnetofingerprints of superconducting films: Vortex dynamics and mesoscopic-scale disorder

    International Nuclear Information System (INIS)

    Nowak, E.R.; Israeloff, N.E.; Goldman, A.M.

    1994-01-01

    The variations of voltage and voltage noise with magnetic field in c-axis-oriented DyBa 2 Cu 3 O 7-δ thin films exhibit reproducible, microstructure-dependent ''magnetofingerprints'' (MF's). The MF's can be scrambled with the reversal of the direction of the Lorentz force on field-induced vortices. Analysis of the noise suggests a strong dependence of the local free-energy landscape on vortex density similar to global frustration effects found in periodic superconducting networks. Above fields which roughly match vortex separation with mesoscopic-scale disorder in the films the noise and the fine structure of the MF's are suppressed, suggesting a crossover to a more weakly pinned vortex-liquid regime

  9. Specific heat measurement set-up for quench condensed thin superconducting films.

    Science.gov (United States)

    Poran, Shachaf; Molina-Ruiz, Manel; Gérardin, Anne; Frydman, Aviad; Bourgeois, Olivier

    2014-05-01

    We present a set-up designed for the measurement of specific heat of very thin or ultra-thin quench condensed superconducting films. In an ultra-high vacuum chamber, materials of interest can be thermally evaporated directly on a silicon membrane regulated in temperature from 1.4 K to 10 K. On this membrane, a heater and a thermometer are lithographically fabricated, allowing the measurement of heat capacity of the quench condensed layers. This apparatus permits the simultaneous thermal and electrical characterization of successively deposited layers in situ without exposing the deposited materials to room temperature or atmospheric conditions, both being irreversibly harmful to the samples. This system can be used to study specific heat signatures of phase transitions through the superconductor to insulator transition of quench condensed films.

  10. Ginzburg-Landau theory and the superconducting transition in thin, amorphous bismuth films

    International Nuclear Information System (INIS)

    Van Vechten, D.

    1979-01-01

    The Aslamasov-Larkin (AL) theory can be derived from a classical treatment of the conductivity due to short-lived statistical fluctuations into the superconducting state if one truncates the Ginzburg-Landau free energy density expression to read F[psi] = α 0 vertical barpsi vertical bar 2 + c 0 vertical bar del psi vertical bar 2 , where psi is the superconducting order parameter. The next largest term in the GL free energy is (b/2) (vertical bar psi vertical bar 2 ) 2 and is conventionally interpreted as representing the energy associated with interactions between the fluctuations. My dissertation consists of the calculation of the effect of this term on the fluctuation conductivity in three different approximations and the comparison of my predictions to the data of R.E. Glover III and M.K. Chien on thin amorphous bismuth films. The first approximation calculates the contribution to the fluctuations' self energy of the ''tadpole'' diagrams. This approximation yields a 4 parameter equation. Its fits were particularly outstanding for the films deposited on quartz or roughened glass substrates and only for two smooth glass substrates were there non-isolated data points that were not fit at the lowest temperatures measured. (The equation runs into trouble for these films at approximately R(T)/R/sub o/ =.08.) The values of the theoretical equation's fitting parameters were determined by a least squares method and turns out to depend on film thickness in the manner predicted by the theory. The next calculation improves the self energy approximation by including all the ''ring'' diagrams

  11. Superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Batistoni, Paola; De Marco, Francesco; Pieroni, Leonardo [ed.

    2005-07-01

    Research on superconductivity at ENEA is mainly devoted to projects related to the ITER magnet system. In this framework, ENEA has been strongly involved in the design, manufacturing and test campaigns of the ITER toroidal field model coil (TFMC), which reached a world record in operating current (up to 80 kA). Further to this result, the activities in 2004 were devoted to optimising the ITER conductor performance. ENEA participated in the tasks launched by EFDA to define and produce industrial-scale advanced Nb3Sn strand to be used in manufacturing the ITER high-field central solenoid (CS) and toroidal field (TF) magnets. As well as contributing to the design of the new strand and the final conductor layout, ENEA will also perform characterisation tests, addressing in particular the influence of mechanical stress on the Nb3Sn performance. As a member of the international ITER-magnet testing group, ENEA plays a central role in the measurement campaigns and data analyses for each ITER-related conductor and coil. The next phase in the R and D of the ITER magnets will be their mechanical characterisation in order to define the fabrication route of the coils and structures. During 2004 the cryogenic measurement campaign on the Large Hadron Collider (LHC) by-pass diode stacks was completed. As the diode-test activity was the only LHC contract to be finished on schedule, the 'Centre Europeenne pour la Recherche Nucleaire' (CERN) asked ENEA to participate in an international tender for the cold check of the current leads for the LHC magnets. The contract was obtained, and during 2004, the experimental setup was designed and realised and the data acquisition system was developed. The measurement campaign was successfully started at the end of 2004 and will be completed in 2006.

  12. Stability of Tl-Ba-Ca-Cu-O Superconducting Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Siegal, M.P.; Overmyer, D.L.; Venturini, E.L.; Padilla, R.R.; Provencio, P.N.

    1999-08-23

    We report the stability of TlBa{sub 2}CaCu{sub 2}O{sub 7} (Tl-1212) and Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub 8} (T1-2212) thin films and by inference, the stability of TlBa{sub 2}Ca{sub 2}Cu{sub 3}O{sub 9} (Tl-1223) and Tl{sub 2}Ba{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10} (Tl-2223) thin films, under a variety of conditions. In general, we observe that the stability behavior of the single Tl-O layer materials (Tl-1212 and Tl-1223)are similar and the double Tl-O layer materials (Tl-2212 and Tl-2223) are similar. All films are stable with repeated thermal cycling to cryogenic temperatures. Films are also stable in acetone and methanol. Moisture degrades film quality rapidly, especially in the form of vapor. Tl-1212 is more sensitive to vapor than Tl-2212. These materials are stable to high temperatures in either N{sub 2}, similar to vacuum for the cuprates, and O{sub 2} ambients. While total degradation of properties (superconducting and structural) occur at the same temperatures for all phases, 600 C in N{sub 2} and 700 C in O{sub 2}, the onset of degradation occurs at somewhat lower temperatures for Tl-1212 than for Tl-2212 films. In all cases, sample degradation is associated with Tl depletion from the films.

  13. Nanoscale wedge polishing of superconducting thin films-an easy way to obtain depth dependent information by surface analysis techniques

    International Nuclear Information System (INIS)

    Shapoval, T; Engel, S; Gruendlich, M; Meier, D; Backen, E; Neu, V; Holzapfel, B; Schultz, L

    2008-01-01

    A mechanical wedge polishing procedure that offers a simple, cost-effective and rapid way to look into the depth of a thin film with different surface-sensitive scanning techniques has been developed. As an example of its wide applicability, this method was utilized for the investigation of two differently prepared superconducting YBa 2 Cu 3 O 7-δ thin films: an Hf-doped film prepared by chemical solution deposition and an undoped film grown by pulsed laser deposition. Upon polishing, the roughness of the samples was reduced to less than 5 nm (peak-to-valley) without influencing the superconducting properties of the films. Thus, nanoscale polishing opens up a unique possibility for microscopic studies with various surface-sensitive techniques. We demonstrate the successful imaging of flux lines by low temperature magnetic force microscopy after polishing a formerly rough as-prepared film. By applying the wedge polishing procedure to the Hf-doped sample, high resolution electron backscattering diffraction investigations reveal the homogeneous distribution of non-superconducting BaHfO 3 nanoparticles in the whole volume of the film

  14. Microstructure imaging of the YBCO thin film/MgO substrate interface: HRTEM and Fourier analysis of the Moire fringe pattern

    International Nuclear Information System (INIS)

    Auzary, S.; Pailloux, F.; Denanot, M.F.; Gaboriaud, R.J.

    1998-01-01

    Detailed microstructural aspects of the interface between YBaCuO thin films and MgO substrate are studied by means of a Fourier analysis of Moire fringe pattern obtained from HRTEM investigations of plan view samples. The main features of the observations are large, well oriented crystallographic domains surrounded by wide boundaries. HRTEM investigations together with the Fourier analysis show evidence of both orthorhombic and pseudo-tetragonal structure in the YBaCuO film. An accommodation mechanism is suggested from the Fourier analysis of the Moire fringe pattern. (orig.)

  15. An evaluation of phase separated, self-assembled LaMnO3-MgO nanocomposite films directly on IBAD-MgO as buffer layers for flux pinning enhancements in YBa2YCu3O7-& coated conductors

    Energy Technology Data Exchange (ETDEWEB)

    Polat, Ozgur [ORNL; Aytug, Tolga [ORNL; Paranthaman, Mariappan Parans [ORNL; Leonard, Keith J [ORNL; Lupini, Andrew R [ORNL; Pennycook, Stephen J [ORNL; Meyer III, Harry M [ORNL; Kim, Kyunghoon [ORNL; Qiu, Xiaofeng [ORNL; Cook, Sylvester W [ORNL; Thompson, James R [ORNL; Christen, David K [ORNL; Goyal, Amit [ORNL; Selvamanickam, V. [SuperPower Incorporated, Schenectady, New York; Xiong, X. [SuperPower Incorporated, Schenectady, New York

    2010-01-01

    Technological applications of high temperature superconductors (HTS) require high critical current density, Jc, under operation at high magnetic field strengths. This requires effective flux pinning by introducing artificial defects through creative processing. In this work, we evaluated the feasibility of mixed-phase LaMnO3:MgO (LMO:MgO) films as a potential cap buffer layer for the epitaxial growth and enhanced performance of YBa2Cu3O7-d (YBCO) films. Such composite films were sputter deposited directly on IBAD-MgO templates (with no additional homo-epitaxial MgO layer) and revealed the formation of two phase-separated, but at the same time vertically aligned, self-assembled composite nanostructures that extend throughout the entire thickness of the film. The YBCO coatings deposited on these nanostructured cap layers showed correlated c-axis pinning and improved in-field Jc performance compared to those of YBCO films fabricated on standard LMO buffers. Microstructural characterization revealed additional extended disorder in the YBCO matrix. The present results demonstrate the feasibility of novel and potentially practical approaches in the pursuit of more efficient, economical, and high performance superconducting devices.

  16. Development of a fluorine-free chemical solution deposition route for rare-earth cuprate superconducting tapes and its application to reel-to-reel processing

    DEFF Research Database (Denmark)

    Tang, Xiao

    temperature, REBCO (RE= rare earth) has some evident advantages compared to other high-temperature superconductors in retaining high current densities under strong magnetic fields, thus REBCO high temperature superconducto rs have significant potential for high field engineering applications. Compared...... to Pulsed Laser Deposition (PLD) and Chemical Vapor Deposition (CVD), the trifluoroacetate metal-organic deposition (TFA-MOD) route is more promising for producing REBCO superconducting films, owing to the high-Jc, high reproducibility, and low cost of this technique, which doesn't require any high vacuum...... on the microstructure and performance of FF-MOD derived YBCO films was investigated. Chapter 9 is the summary of the thesis....

  17. Control of Flux Pinning in MOD YBCO Coated Conductor

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, W. [American Superconductor Corporation, Westborough, MA; Huang, Y. [American Superconductor Corporation, Westborough, MA; Li, X. [American Superconductor Corporation, Westborough, MA; Kodenkandath, Thomas [American Superconductor Corporation, Westborough, MA; Rupich, Marty [American Superconductor Corporation, Westborough, MA; Schoop, U. [American Superconductor Corporation, Westborough, MA; Verebelyi, D. T. [American Superconductor Corporation, Westborough, MA; Thieme, C. L. H. [American Superconductor Corporation, Westborough, MA; Siegal, E. E. [American Superconductor Corporation, Westborough, MA; Holesinger, T. G. [Los Alamos National Laboratory (LANL); Maiorov, B. [Los Alamos National Laboratory (LANL); Miller, D. J. [Argonne National Laboratory (ANL); Maroni, V. A. [Argonne National Laboratory (ANL); Goyal, Amit [ORNL; Specht, Eliot D [ORNL; Paranthaman, Mariappan Parans [ORNL

    2007-01-01

    Two different types of defect structures have been identified to be responsible for the enhanced pinning in metal organic deposited YBCO films. Rare earth additions result in the formation of nanodots in the YBCO matrix, which form uncorrelated pinning centers, increasing pinning in all magnetic field orientations. 124-type intergrowths, which form as laminar structures parallel to the ab-plane, are responsible for the large current enhancement when the magnetic field is oriented in the ab-plane. TEM studies showed that the intergrowths emanate from cuprous containing secondary phase particles, whose density is partially controlled by the rare earth doping level. Critical process parameters have been identified to control this phase formation, and therefore, control the f 24 intergrowth formation. This work has shown that through process control and proper conductor design, either by adjusting the composition or by multiple coatings of different functional layers, the desired angular dependence can be achieved.

  18. Control of flux pinning in MOD YBCO coated conductor.

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, W.; Huang, Y.; Li, X.; Kodenkandath, T.; Rupich, M. W.; Schoop, U.; Verebelyi, D. T.; Thieme, C. L. H.; Siegal, E.; Holesinger, T. G.; Maiorov, B.; Civale, L.; Miller, D. J.; Maroni, V. A.; Li, J.; Martin, P. M.; Specht, E. D.; Goyal, A.; Paranthaman, M. P.; American Superconductor Corp.; LANL; ORNL

    2007-06-01

    NTwo different types of defect structures have been identified to be responsible for the enhanced pinning in metal organic deposited YBCO films. Rare earth additions result in the formation of nanodots in the YBCO matrix, which form uncorrelated pinning centers, increasing pinning in all magnetic field orientations. 124-type intergrowths, which form as laminar structures parallel to the ab-plane, are responsible for the large current enhancement when the magnetic field is oriented in the ab-plane. TEM studies showed that the intergrowths emanate from cuprous containing secondary phase particles, whose density is partially controlled by the rare earth doping level. Critical process parameters have been identified to control this phase formation, and therefore, control the f 24 intergrowth formation. This work has shown that through process control and proper conductor design, either by adjusting the composition or by multiple coatings of different functional layers, the desired angular dependence can be achieved.

  19. Zone refining of sintered, microwave-derived YBCO superconductors

    International Nuclear Information System (INIS)

    Warrier, K.G.K.; Varma, H.K.; Mani, T.V.; Damodaran, A.D.; Balachandran, U.

    1993-07-01

    Post-sintering treatments such as zone melting under thermal gradient has been conducted on sintered YBCO tape cast films. YBCO precursor powder was derived through decomposition of a mixture of nitrates of cations in a microwave oven for ∼4 min. The resulting powder was characterized and made into thin sheets by tape casting and then sintered at 945 C for 5 h. The sintered tapes were subjected to repeated zone refining operations at relatively high speeds of ∼30 mm/h. A microstructure having uniformly oriented grains in the a-b plane throughout the bulk of the sample was obtained by three repeated zone refining operations. Details of precursor preparation, microwave processing and its advantages, zone refining conditions, and microstructural features are presented in this paper

  20. New method of synthesis and physical properties of thick superconducting Er-123 films

    International Nuclear Information System (INIS)

    Muralidhar, M.; Sakai, N.; Machi, T.; Miyajiri, T.; Hirabayashi, I.; Tanaka, S.

    2008-01-01

    We have developed a low-cost, short time manufacturing process using a novel method, starting from a mixture of Er 2 BaO 4 , BaCuO 2 , and CuO, with an excess of Er at expense of Ba. Several micrometers thick films were prepared by the screen-printing technique, spreading the mixture paste on silver substrates, processed then in Ar-1% O 2 atmosphere. Using a double-step annealing process, we obtained good quality Er-123 thick films on silver substrates, with T c (onset) 92 K. Formation of large flat grains was observed by scanning electron microscope. According to XRD analysis, the films were preferentially c-axis oriented. The magnetic (induced), self-field J c measured at 77 K was above 32 kA/cm 2 . We observed a strong dependence of the transport current, I c , on the grain size. The maximum I c at 77 K as high as 10 A was observed in the sample with the average grain size around 40 μm. The present results indicate that our technology, enabling preparation of large-area superconducting thick films on Ag-based substrates in short processing times, is relatively cheap and appropriate for utilization in long-length RE-123 silver sheath wire production for commercial applications

  1. Quasi-two-dimensional superconductivity in wurtzite-structured InN films

    International Nuclear Information System (INIS)

    Ling, D.C.; Cheng, J.H.; Lo, Y.Y.; Du, C.H.; Chiu, A.P.; Chang, P.H.; Chang, C.A.

    2007-01-01

    C-axis oriented InN films with wurtzite structure were grown on sapphire(0001) substrate by MOCVD method. Superconductivity with transition onset temperature T c,onset around 3.5 K has been characterized by magnetotransport measurements in fields up to 9 Tesla for films with carrier concentration in the range of 1 x 10 19 cm -3 to 7 x 10 20 cm -3 . Among them, the film with a nitridation buffer layer has the highest zero-resistance temperature T c0 of 2 K. The normal-state magnetoresistance follows Kohler's rule ΔR/R∝(H/R) 2 , indicating that there is a single species of charge carrier with single scattering time at all points on the Fermi surface. The extrapolated value of zero-temperature upper critical field H c2 ab (0) and H c2 c (0) is estimated to be 5900 G and 2800 G, respectively, giving rise to the anisotropy parameter γ about 2.1. The angular dependence of the upper critical field is in good agreement with the behavior predicted by Lawrence-Doniach model in the two-dimensional (2D) limit strongly suggesting that the InN film is a quasi-2D superconductor. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. YBa2Cu3O7-δ thin films deposited by MOCVD vertical reactor with a flow guide

    International Nuclear Information System (INIS)

    Sujiono, E.H.; Negeri Makassar; Sani, R.A.; Saragi, T.; Arifin, P.; Barmawi, M.

    2001-01-01

    The effect of a flow guide in a vertical MOCVD reactor on the deposition uniformity and growth rate of thin YBCO films has been studied. Without the flow guide the growth rates are low, have a poor uniformity and the film composition is not stoichiometric. The growth rate of the films grown using a reactor with the flow guide was approximately twice that without the flow guide. Using this flow guide the growth rates were 0.4-0.7 μm/h for growth temperatures varying between 600 and 750 C, and the crystalline quality as well as the surface morphology of YBCO films on MgO substrates is improved. For films grown at temperatures above 650 C the composition of Y:Ba:Cu is 1:2:3, as confirmed by EDAX spectra. Films deposited without and with the flow guide at 700 C have critical temperatures around 85 and 88 K, respectively. The reduction in ΔT c (T c,zero -T c,onset ) also shows an improvement of the superconducting properties of YBCO thin films deposited with a flow guide. (orig.)

  3. Roughness analysis applied to niobium thin films grown on MgO(001) surfaces for superconducting radio frequency cavity applications

    OpenAIRE

    D. B. Beringer; W. M. Roach; C. Clavero; C. E. Reece; R. A. Lukaszew

    2013-01-01

    This paper describes surface studies to address roughness issues inherent to thin film coatings deposited onto superconducting radio frequency (SRF) cavities. This is particularly relevant for multilayered thin film coatings that are being considered as a possible scheme to overcome technical issues and to surpass the fundamental limit of ∼50  MV/m accelerating gradient achievable with bulk niobium. In 2006, a model by Gurevich [Appl. Phys. Lett. 88, 012511 (2006)APPLAB0003-695110.1063/1.2162...

  4. Femtosecond optical detection of quasiparticle dynamics in high-Tc YBa2Cu3O7-δ superconducting thin films

    International Nuclear Information System (INIS)

    Han, S.G.; Vardeny, Z.V.; Wong, K.S.; Symko, O.G.; Koren, G.

    1990-01-01

    Femtosecond dynamics of photogenerated quasiparticles in YBa 2 Cu 3 O 7-δ superconducting thin films shows, at T≤T c , two main electronic processes: (i) quasiparticle avalanche production during hot-carrier thermalization, which takes about 300 fsec; (ii) recombination of quasiparticles to form Cooper pairs, which is completed within 5 psec. In contrastr, nonsuperconducting epitaxial films such as PrBa 2 Cu 2 O 7 and YBa 2 Cu 3 O 6 show regular picosecond electronic response

  5. Dynamics of vortex matter in YBCO sub-micron bridges

    Energy Technology Data Exchange (ETDEWEB)

    Papari, G., E-mail: papari@fisica.unina.it [Dipartimento di Fisica, Università degli Studi di Napoli Federico II, I-80126 Napoli (Italy); Carillo, F. [NEST, CNR-NANO and Scuola Normale Superiore, Piazza San Silvestro 12, 56127 Pisa (Italy); Stornaiuolo, D.; Massarotti, D. [Dipartimento di Fisica, Università degli Studi di Napoli Federico II, I-80126 Napoli (Italy); CNR-SPIN UOS Napoli, Complesso Universitario di Monte SantAngelo, via Cinthia, 80126 Napoli (Italy); Longobardi, L. [American Physical Society, 1 Research Road, Ridge, NY 11961 (United States); Beltram, F. [NEST, CNR-NANO and Scuola Normale Superiore, Piazza San Silvestro 12, 56127 Pisa (Italy); Tafuri, F. [CNR-SPIN UOS Napoli, Complesso Universitario di Monte SantAngelo, via Cinthia, 80126 Napoli (Italy); Dipartimento di Ingegneria Industriale e dell' informazione, Seconda Universit‘a di Napoli, via Roma 29, 81031 Aversa (CE) (Italy)

    2014-11-15

    Highlights: • Superconducting properties of YBCO nanowires in the width range ξYBCO nanowires displaying robust superconductivity at widths w as low as 160 nm. We can modify the process in order to maintain a Au protective layer. This allows us to scale our nanowires even further to widths as low as 50 nm. We have studied how the presence of vortices and the occurrence of phase slips affect the transport properties of nanowires in the width range ξ

  6. Y1Ba2Cu3O(7-delta) thin film dc SQUIDs (superconducting quantum interference device)

    Science.gov (United States)

    Racah, Daniel

    1991-03-01

    Direct current superconducting quantum interferometers (SQUIDs) based on HTSC thin films have been measured and characterized. The thin films used were of different quality: (1) Granular films on Sapphire substrates, prepared either by e-gun evaporation, by laser ablation or by MOCVD (metal oxide chemical vapor deposition), (2) Epitaxial films on MgO substrates. Modulations of the voltage on the SQUIDs as a function of the applied flux have been observed in a wide range of temperatures. The nature of the modulation was found to be strongly dependent on the morphology of the film and on its critical current. The SQUIDs based on granular films were relatively noisy, hysteretic and with a complicated V-phi shape. Those devices based on low quality (lowIc) granular films could be measured only at low temperatures (much lower than 77 K). While those of higher quality (granular films with high Ic) could be measured near to the superconductive transition. The SQUID based on high quality epitaxial film was measured near Tc and showed an anomalous, time dependent behavior.

  7. Laser writing of superconducting patterns on YBa2Cu3Ox films

    International Nuclear Information System (INIS)

    Dye, R.C.; Muenchausen, R.E.; Nogar, N.S.; Mukherjee, A.; Brueck, S.R.J.

    1990-01-01

    A novel process for the direct laser writing of thin-film high T c patterns is demonstrated. The process consists of deposition of a high quality film (308 nm laser ablation from a YBa 2 Cu 3 O x target with a 750 degree C substrate temperature and a 150 mTorr O 2 ambient), annealing in an inert atmosphere (Ar at 400 degree C for 5--20 min) to reduce the oxygen content and depress or eliminate the superconducting transition temperature, and direct-write laser heating (1.06 μm at ∼0.5 kW/cm 2 for ∼5 min) in an oxygen atmosphere at ∼590 Torr to selectively regenerate the high T c material. rf eddy current and four-point resistivity probe results confirm this process for both SrTiO 3 and LaAlO 3 substrates. Scanning electron micrographs indicate that this is a very mild processing sequence with no observable changes in film morphology

  8. Study of the surface resistance of superconducting niobium films at 1.5 GHz

    CERN Document Server

    Benvenuti, Cristoforo; Campisi, I E; Darriulat, Pierre; Peck, M A; Russo, R; Valente, A M

    1999-01-01

    A systematic study of superconducting properties of niobium films sputtered on the inner wall of radiofrequency cavities is presented. The measured quantities include in particular the response to 1.5 GHz microwaves, the critical temperature, the penetration depth and the magnetic penetration field. In addition to films grown in different gas discharges (Xe, Kr, Ar and Ar/Ne mixtures) and to films grown on substrates prepared under different conditions, the study also includes bulk niobium cavities. The surface resistance is analysed in terms of its dependence on temperature, on RF field and, when relevant, on the density of trapped fluxons. A simple parameterisation is found to give a good fit to the data. Once allowance for the presence of impurities and defects is made by means of a single parameter, the electron mean free path, good agreement with BCS theory is observed. The fluxon-induced losses are studied in detail and their dependence on RF field, on temperature and on the density of trapped fluxons i...

  9. A study on the superconducting properties of YBa2Cu9-xNbxOy thin films

    International Nuclear Information System (INIS)

    Srinivas, S.; Bhatnagar, A.K.; Pinto, R.

    1994-01-01

    Effect of niobium substitution at the copper site in YBa 2 Cu 9 O 7-x was studied in thin film form. The films were deposited by laser ablation technique using the targets of the YBa 2 Cu 3-x Nb x O y where x = 0.0, 0.025, 0.05, 0.1, 0.2, 0.4, 0.8 and 1.0 under identical deposition conditions on SrTiO 9 substrates. Films were characterized by XRD, resistivity, I-V and J c measurements. Films made from x = 0.025 and 0.05 concentrations of Nb substituted targets showed relatively improved superconducting properties compared to that of undoped films. The best 7 realized for x = 0.025 Nb concentration was 1.8 x 10 σ A/cm 2 and for 0.05 Nb concentration it was 3.2x10 σ A/cm 2 at 77K. However, degradation of the superconducting properties, with the increase of x ≥ 0.1 Nb concentration and drastic suppression and complete loss of superconductivity was noticed for x ≥ 0.4. The growth of impurity phase YBa 2 NbO 6 for x = 0.1 and above of Nb concentration was noticed from XRD patterns. However, the site occupancy of Nb could not be confirmed from these studies

  10. Composite vortex ordering in superconducting films with arrays of blind holes

    International Nuclear Information System (INIS)

    Berdiyorov, G R; Milosevic, M V; Peeters, F M

    2009-01-01

    The pinning properties of a superconducting thin film with a square array of blind holes are studied using the nonlinear Ginzburg-Landau theory. Although blind holes provide a weaker pinning potential than holes (also called antidots), several novel vortex structures are predicted for different size and thickness of the blind holes. Orientational dimer and trimer vortex states as well as concentric vortex shells can nucleate in the blind holes. In addition, we predict the stabilization of giant vortices that may be located both in the pinning centers and/or at the interstitial sites, as well as the combination of giant vortices with sets of individual vortices. For large blind holes, local vortex shell structures inside the blind holes may transfer their symmetry to interstitial vortices as well. The subtle interplay of shell formation and traditional Abrikosov vortex lattices inside the blind holes is also studied for different numbers of trapped vortices.

  11. Vortex lattice in effective type-I superconducting films with periodic arrays of submicron holes

    International Nuclear Information System (INIS)

    Berdiyorov, G.R.; Milosevic, M.V.; Peeters, F.M.

    2006-01-01

    The vortex matter and related phenomena in superconducting films with periodic arrays of microholes (antidots) are studied within the nonlinear Ginzburg-Landau (GL) theory. By varying the GL parameter κ, the vortex-vortex interaction is fine tuned, from repulsive to attractive behavior. This interaction is of crucial importance for equilibrium vortex structures, the saturation number of the antidots, and the related quantities, such as critical current. Due to vortex attraction in effectively type-I samples, the giant-vortex state becomes energetically favorable (contrary to the type-II behavior). For the same reason, the number of vortices which can be captured by antidots, increases with decreasing κ. As a result, for given magnetic field, the critical current is larger for effectively type-I superconductors than in conventional type-II cases

  12. Anisotropic behaviour of transmission through thin superconducting NbN film in parallel magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Šindler, M., E-mail: sindler@fzu.cz [Institute of Physics ASCR, v. v. i., Cukrovarnická 10, CZ-162 53 Praha 6 (Czech Republic); Tesař, R. [Institute of Physics ASCR, v. v. i., Cukrovarnická 10, CZ-162 53 Praha 6 (Czech Republic); Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3, CZ-121 16 Praha (Czech Republic); Koláček, J. [Institute of Physics ASCR, v. v. i., Cukrovarnická 10, CZ-162 53 Praha 6 (Czech Republic); Skrbek, L. [Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3, CZ-121 16 Praha (Czech Republic)

    2017-02-15

    Highlights: • Transmission through thin NbN film in parallel magnetic field exhibits strong anisotropic behaviour in the terahertz range. • Response for a polarisation parallel with the applied field is given as weighted sum of superconducting and normal state contributions. • Effective medium approach fails to describe response for linear polarisation perpendicular to the applied magnetic field. - Abstract: Transmission of terahertz waves through a thin layer of the superconductor NbN deposited on an anisotropic R-cut sapphire substrate is studied as a function of temperature in a magnetic field oriented parallel with the sample. A significant difference is found between transmitted intensities of beams linearly polarised parallel with and perpendicular to the direction of applied magnetic field.

  13. Microwave surface resistance of YBa2Cu3O/sub 6.9/ superconducting films

    International Nuclear Information System (INIS)

    Martens, J.S.; Beyer, J.B.; Ginley, D.S.

    1988-01-01

    The microwave surface resistance of an YBa 2 Cu 3 O/sub 6.9/ superconducting thick film was measured over the range 7.0--16.7 GHz at 77 K. This was done by placing a sample in a TE 01 /sub n/ wavemeter cavity and observing the change in selectivity of the cavity. The material's surface resistance is of the same order of magnitude as that of silver at 77 K from 8 to 12 GHz and improves about another order at 4.2 K. The power-law behavior of surface resistance with frequency is probably close to quadratic. This is similar to the behavior of low critical temperature superconductors

  14. Anisotropic response of the moving vortex lattice in superconducting Mo(1-x)Gex amorphous films

    International Nuclear Information System (INIS)

    Dolz, M.I.; Shalóm, D.E.; Pastoriza, H.; López, D.O.

    2012-01-01

    We have performed magnetic susceptibility measurements in Mo 1-x Ge x amorphous thin films biased with an electrical current using anisotropic coils. We tested the symmetry of the vortex response changing the relative orientation between the bias current and the susceptibility coils. We found a region in the DC current-temperature phase diagram where the dynamical vortex structures behave anisotropically. In this region the shielding capability of the superconducting currents measured by the susceptibility coils is less effective along the direction of vortex motion compared to the transverse direction. This anisotropic response is found in the same region where the peak effect in the critical current is developed. On rising temperature the isotropic behavior is recovered.

  15. Electron mean free path dependence of the critical currents and the pair-breaking limit in superconducting films

    International Nuclear Information System (INIS)

    Fedorov, N.; Rinderer, L.

    1977-01-01

    We have studied the current-induced breakdown of superconductivity in wide (100--980 μm) and thin (0.25--0.98 μm) films of tin. It is shown that the current at which the resistance of the sample begins to rise rapidly in the process of the destruction of superconductivity by a current can be fairly well associated with the theoretical value of the pair-breaking current in the Ginzburg-Landau phenomenological approach (I/sub c//sup G L/). This effect is observed over a rather wide temperature region (up to ΔTapprox.0.7 K), depending on the electron mean free path in the films. The values of the critical currents outside the above-mentioned region correlate qualitatively with those determined by inhomogeneities of the films as proposed by Larkin and Ovchinnikov

  16. Transport in reversibly laser-modified YBa2Cu3O/sub 7-//sub x/ superconducting thin films

    International Nuclear Information System (INIS)

    Krchnavek, R.R.; Chan, S.; Rogers, C.T.; De Rosa, F.; Kelly, M.K.; Miceli, P.F.; Allen, S.J.

    1989-01-01

    A focused argon ion laser beam in a controlled ambient is used to modify the transport properties of superconducting YBa 2 Cu 3 O/sub 7-//sub x/ thin films. The laser-modified region shows a sharp transition temperature (T/sub c/≅76 K) that is reduced from the unmodified regions of the film (T/sub c/≅87 K). In situ monitoring of the room-temperature electrical resistance is used to control the laser processing and prevent formation of the semiconducting phase. The original properties of the superconducting film can be recovered by plasma oxidation indicating that the laser-induced phase is oxygen deficient

  17. AFM studies on heavy ion irradiated YBCO single crystals

    International Nuclear Information System (INIS)

    Lakhani, Archana; Marhas, M.K.; Saravanan, P.; Ganesan, V.; Srinivasan, R.; Kanjilal, D.; Mehta, G.K.; Elizabeth, Suja; Bhat, H.L.

    2000-01-01

    Atomic Force Microscopy (AFM) is extensively used to characterise the surface morphology of high energy ion irradiated single crystals of high temperature superconductor - YBCO. Our earlier systematic studies on thin films of YBCO under high energy and heavy ion irradiation shows clear evidence of ion induced sputtering or erosion, even though the effect is more on the grain boundaries. These earlier results were supported by electrical resistance measurements. In order to understand more clearly, the nature of surface modification at these high energies, AFM studies were carried out on single crystals of YBCO. Single crystals were chosen in order to see the effect on crystallites alone without interference from grain boundaries. 200 MeV gold ions were used for investigation using the facilities available at Nuclear Science Centre, New Delhi. The type of ion and the range of energies were chosen to meet the threshold for electronically mediated defect production. The results are in conformity with our earlier studies and will be described in detail in the context of electronic energy loss mediated sputtering or erosion. (author)

  18. Quantum and superconducting fluctuations effects in disordered Nb 1- xTa x thin films above Tc

    Science.gov (United States)

    Giannouri, M.; Papastaikoudis, C.

    1999-05-01

    Disordered Nb 1- xTa x thin films are prepared with e-gun coevaporation. The influence of the β-phase of tantalum in the critical temperature Tc is observed as a function of the substrate temperature. The measurements of transverse magnetoresistance at various isothermals are interpreted in terms of weak-localization and superconducting fluctuations. From the fitting procedure, the phase breaking rate τφ-1 and the Larkin parameter βL are estimated as a function of temperature. Conclusions about the dominant inelastic scattering mechanisms at various temperature regions as well as for the dominant mechanism of superconducting fluctuations near the transition temperature are extracted.

  19. Estimation of magnetic relaxation property for CVD processed YBCO-coated conductors

    International Nuclear Information System (INIS)

    Takahashi, Y.; Kiuchi, M.; Otabe, E.S.; Matsushita, T.; Shikimachi, K.; Watanabe, T.; Kashima, N.; Nagaya, S.

    2010-01-01

    Ion Beam Assist Deposition/Chemical Vapor Deposition(IBAD/CVD)-processed YBCO-coated conductors with high critical current density J c at high magnetic fields are expected to be applied to superconducting equipments such as superconducting magnetic energy storage (SMES). For application to superconducting magnet in SMES one of the most important properties for superconductors is the relaxation property of superconducting current. In this paper, the relaxation property is investigated for IBAD/CVD-processed YBCO-coated conductors of the superconducting layer in the range of 0.18-0.90 μm. This property can be quantitatively characterized by the apparent pinning potential, U 0 *. It is found that U 0 * takes a smaller value due to the two-dimensional pinning mechanism at high magnetic fields for conductor with thinner superconducting layer. Although U 0 * decreases with increasing thickness at low magnetic fields at 20 K, it increases at high magnetic fields. The results are theoretically explained by the model of the flux creep and flow based on the dimensionality of flux pinning. Scaling analysis is examined for the dependence of U 0 * on the magnetic field, temperature and the layer thickness.

  20. Surface characterization of superconductive Nd1Ba2Cu3Oy thin films using scanning probe microscopes

    International Nuclear Information System (INIS)

    Ting, W.; Badaye, M.; Itti, R.; Morishita, T.; Koshizuka, N.; Tanaka, S.

    1996-01-01

    Recently, superconductive Nd 1 Ba 2 Cu 3 O y (Nd123) thin films with high superconducting transition temperature (T c ) have been successfully fabricated at the authors institute employing the standard laser ablation method. In this paper, they report parts of the results of surface characterization of the Nd123 thin films using an ultrahigh vacuum scanning tunneling microscope/spectroscopy (UHV-STM/STS) and an atomic force microscope (AFM) system operated in air. Clear spiral pattern is observed on the surfaces of Nd123 thin films by STM and AFM, suggesting that films are formed by two-dimensional island growth mode at the final growing stage. Contour plots of the spirals show that the step heights of the spirals are not always the integer or half integer numbers of the c-axis parameter of the structure. This implies that the surface natural termination layer of the films may not be unique. Surface atomic images of the as-prepared Nd123 thin films are obtained employing both STM and AFM. STS measurements show that most of the surfaces are semiconductive, or sometimes even metallic. The results of STS measurements together with the fact that they are able to see the surface atomic images using scanning probe microscopes suggest that exposure to air does not cause serious degradation to the as-prepared surfaces of Nd123 thin films

  1. Numerical simulation and analysis of single grain YBCO processed from graded precursor powders

    OpenAIRE

    Zou, J; Ainslie, Mark Douglas; Hu, D; Zhai, W; Kumar, N Devendra; Durrell, John Hay; Shi, Yunhua; Cardwell, David Anthony

    2015-01-01

    Large single-grain bulk high-temperature superconducting materials can trap high magnetic fields in comparison with conventional permanent magnets, making them ideal candidates to develop more compact and efficient devices, such as actuators, magnetic levitation systems, flywheel energy storage systems and electric machines. However, macro-segregation of Y-211 inclusions in melt processed Y–Ba–Cu–O (YBCO) limits the macroscopic critical current density Jc of such bulk supercond...

  2. Parallel critical magnetic fields of superconducting hyperthin films of vanadium and technetium

    International Nuclear Information System (INIS)

    Teplov, A.A.; Mikheeva, M.N.

    1980-01-01

    The nature of limiting parallel magnetic fields Hsub(c parallel) destroying a superconducting state in films of vanadium and technetium is found out. A dependence of Hsub(c parallel) on the thickness of films up to d approximately 60 A is studied. The |dHsub(c parallel)sup(2)/dT|sub(Tsub(c)) derivative, which increases in the region of large d with the increase of 1/d and achieves the maximum va;ue at d approximately 100 A, was determined, using the experimental data. For the most thin films this derivative tends to drop (the value of the derivative changes from 16 up to 20.00 kOe 2 /k and for technetium and from 4 up to 2100 kOe 2 /k for vanadium). Such stop at |dHsub(c11)sup(2)/ dT|sub(Tsub(c)) growth during the decrease of d is not explained in the framework of the theory taking into account only orbital effects. An account of the additional paramagnetic effect (spin effects) leads to a good agreement of the experiment with the theory in the whole range of thicknesses for vanadium. For technetium films in the d range <=110 A the value of Hsub(c parallel) exceeds several times Hsub(c parallel) calculated with provision of spin effects. For d approximately 80 A and d approximately 55 A this increase achieves the triple value. This effect is explained qualitatively by the spin-orbital scattering appearing with the increase of the atomic number

  3. Two concepts of introducing thin-film superconductivity in Ge and Si by use of Ga-ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Skrotzki, Richard [Dresden High Magnetic Field Laboratory (HLD) and Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden (Germany); Department of Chemistry and Food Chemistry, TU Dresden (Germany); Herrmannsdoerfer, Thomas; Fiedler, Jan; Heera, Viton; Voelskow, Matthias; Muecklich, Arndt; Schmidt, Bernd; Skorupa, Wolfgang; Helm, Manfred; Wosnitza, Joachim [Dresden High Magnetic Field Laboratory (HLD) and Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden (Germany)

    2012-07-01

    We report on two unconventional routes of embedding superconducting nanolayers in a semiconducting environment. Ion implantation and subsequent annealing have been used for preparation of superconducting thin-films of Ga-doped germanium (Ge:Ga) as well as 10 nm thin amorphous Ga-rich layers in silicon (Si:Ga). Structural investigations by means of XTEM, EDX, RBS/C, and SIMS have been performed in addition to low-temperature electrical transport and magnetization measurements. Regarding Ge:Ga, we unravel the evolution of T{sub c} with charge-carrier concentration while for Si:Ga recently implemented microstructuring renders critical-current densities or more than 50 kA/cm{sup 2}. Combined with a superconducting onset at around 10 K, this calls for on-chip application in novel heterostructured devices.

  4. Topological Magnon Bands and Unconventional Superconductivity in Pyrochlore Iridate Thin Films

    Science.gov (United States)

    Laurell, Pontus; Fiete, Gregory A.

    2017-04-01

    We theoretically study the magnetic properties of pyrochlore iridate bilayer and trilayer thin films grown along the [111] direction using a strong coupling approach. We find the ground state magnetic configurations on a mean field level and carry out a spin-wave analysis about them. In the trilayer case the ground state is found to be the all-in-all-out (AIAO) state, whereas the bilayer has a deformed AIAO state. For all parameters of the spin-orbit coupled Hamiltonian we study, the lowest magnon band in the trilayer case has a nonzero Chern number. In the bilayer case we also find a parameter range with nonzero Chern numbers. We calculate the magnon Hall response for both geometries, finding a striking sign change as a function of temperature. Using a slave-boson mean-field theory we study the doping of the trilayer system and discover an unconventional time-reversal symmetry broken d +i d superconducting state. Our study complements prior work in the weak coupling limit and suggests that the [111] grown thin film pyrochlore iridates are a promising candidate for topological properties and unconventional orders.

  5. Topological Magnon Bands and Unconventional Superconductivity in Pyrochlore Iridate Thin Films.

    Science.gov (United States)

    Laurell, Pontus; Fiete, Gregory A

    2017-04-28

    We theoretically study the magnetic properties of pyrochlore iridate bilayer and trilayer thin films grown along the [111] direction using a strong coupling approach. We find the ground state magnetic configurations on a mean field level and carry out a spin-wave analysis about them. In the trilayer case the ground state is found to be the all-in-all-out (AIAO) state, whereas the bilayer has a deformed AIAO state. For all parameters of the spin-orbit coupled Hamiltonian we study, the lowest magnon band in the trilayer case has a nonzero Chern number. In the bilayer case we also find a parameter range with nonzero Chern numbers. We calculate the magnon Hall response for both geometries, finding a striking sign change as a function of temperature. Using a slave-boson mean-field theory we study the doping of the trilayer system and discover an unconventional time-reversal symmetry broken d+id superconducting state. Our study complements prior work in the weak coupling limit and suggests that the [111] grown thin film pyrochlore iridates are a promising candidate for topological properties and unconventional orders.

  6. Influence of annealing atmosphere on structural and superconducting properties of MgB{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Gregor, M., E-mail: gregor@fmph.uniba.sk; Plecenik, T.; Sobota, R.; Brndiarova, J.; Roch, T.; Satrapinskyy, L.; Kus, P.; Plecenik, A.

    2014-09-01

    Highlights: • Superconducting MgB{sub 2} thin film were deposited by co-deposition using the thermal and e-beam evaporation. • Ex situ annealing process was done using various atmospheres. • Influence of annealing atmosphere and temperature on superconducting and structural properties were studied. • Possible mechanisms of the formation and crystallization of MgB{sub 2} thin film are discussed. - Abstract: Influence of an ex situ annealing temperature and atmosphere on chemical composition and structural and superconducting properties of MgB{sub 2} thin films deposited by vacuum evaporation has been investigated. The annealing has been done in Ar, N{sub 2} and Ar + 5%H{sub 2} atmospheres at pressure of 700 Pa and temperature varying from 700 to 800 °C. It has been shown that annealing in Ar and N{sub 2} atmosphere at 700–800 °C produces relatively thick MgO layer on the surface of the films, while creation of such layer is highly reduced if the annealing is done in reducing Ar + 5%H{sub 2} atmosphere. The XPS and XRD results suggest that the MgO layer prevents out-diffusion of Mg from the film during the annealing, what assures better stoichiometry of the films as well as creation of larger MgB{sub 2} grains. The films with the highest amount of MgO on the surface, annealed in nitrogen atmosphere, thus paradoxically exhibited the highest critical temperature of T{sub c0} = 34.8 K with very sharp transition width of 0.1 K.

  7. Solderability study of RABiTS-based YBCO coated conductors

    International Nuclear Information System (INIS)

    Zhang Yifei; Duckworth, Robert C.; Ha, Tam T.; Gouge, Michael J.

    2011-01-01

    Study examines the implication of solder and flux selection in YBCO splice joints. Focus is on commercially available RABiTS-based YBCO coated conductors. Solderability varied with solder and flux for three different stabilizations tested. Resistivity of stabilizer was dominant factor in splice joint resistance. Solder materials affected splice joint resistance when solderability was poor. The solderability of commercially available YBa 2 Cu 3 O 7-x (YBCO) coated conductors that were made from Rolling Assisted Biaxially Textured Substrates (RABiTS)-based templates was studied. The coated conductors, also known as second-generation (2G) high temperature superconductor (HTS) wires (in the geometry of flat tapes about 4 mm wide), were laminated with copper, brass, or stainless steel strips as stabilizers. To understand the factors that influence their solderability, surface profilometry and scanning electron microscopy were used to characterize the wire surfaces. The solderability of three solders, 52In48Sn, 67Bi33In, and 100In (wt.%), was evaluated using a standard test (IPC/ECA J-STD-002) and with two different commercial fluxes. It was found that the solderability varied with the solder and flux but the three different wires showed similar solderability for a fixed combination of solder and flux. Solder joints of the 2G wires were fabricated using the tools and the procedures recommended by the HTS wire manufacturer. The solder joints were made in a lap-joint geometry and with the superconducting sides of the two wires face-to-face. The electrical resistances of the solder joints were measured at 77 K, and the results were analyzed to qualify the soldering materials and evaluate the soldering process. It was concluded that although the selection of soldering materials affected the resistance of a solder joint, the resistivity of the stabilizer was the dominant factor.

  8. Critical current in nonhomogeneous YBCO coated conductors

    International Nuclear Information System (INIS)

    Rostila, L; Mikkonen, R; Lehtonen, J

    2008-01-01

    The critical current of an YBCO tape is determined by the magnetic field inside the YBCO layer and the quality of YBCO material. In thick YBCO layers the average critical current density is reduced by the self-field and decreased material quality. In this paper the combined influence of the material nonhomogeneities and self-field on the critical current of YBCO tapes is scrutinised. First, the zero field critical current density was assumed to decrease along the YBCO thickness. Secondly, the possible defects created in the cutting of YBCO tapes were modelled as a function of lowered critical current density near the tape edges. In both cases the critical current was computed numerically with integral element method. The results suggest that the variation of zero field critical current density, J c0 , along the tape thickness does not effect on the critical current if the mean value of J c0 is kept constant. However, if J c0 is varied along the tape width the critical current can change due to the variated self-field. The computations can be used to determine when it is possible to evaluate the average zero field critical current density from a voltage-current measurement with an appropriate accuracy

  9. High-Tc film development for electronic applications

    International Nuclear Information System (INIS)

    Talvacchio, J.; Wagner, G.R.

    1990-01-01

    In this paper, the authors describe the requirements and status of high-T c superconductor (HTS) films for the development of electronic applications with an emphasis on passive microwave devices. One of the most general requirements, a low rf Surface resistance relative to Cu, has been achieved in films of several different HTS compounds. However the best films, made of YBa 2 Cu 3 O 7 (YBCO) by any one of several techniques, have in common a residual surface resistance that is much greater than predicted by conventional superconductivity theory. Improvement in films is also limited by the current size and selection of single-crystal substrate materials. Other issues that must be resolved to develop a full integrated circuit technology for HTS are substrate heating during film deposition, deposited epitaxial insulators, and determination of which interfaces in a multilevel circuit must be formed in situ

  10. Superconducting Fluctuations above T c and pair breaking parameters of two dimensional Niobium Nitride Films

    Science.gov (United States)

    Shinozaki, B.; Ezaki, S.; Odou, T.; Makise, K.; Asano, T.

    2018-03-01

    Transport properties have been investigated for the epitaxial superconducting NbN thin films. We analysed the excess conductance σ’ ≡ σ(T) - σN by the sum of the Aslamazov-Larkin (AL) and Maki-Thompson (MT) terms for thermal fluctuations above T c, where the σN ≡1/R sq N is the normal state sheet conductance. We have found that the theoretical expression σ’theo (T) = σ’AL (T) + σ’MT (T,δ) can be well fitted to σ’exp (T) with use of the suitable value of the pair breaking parameter δ in the MT term relating to the inelastic scattering rate 1/τin(T) as δ = πħ/8k B Tτin. The rate 1/τin(T) given by the sum of 1/τfluc(T), 1/τe-e(T) and 1/τe-ph (T) is determined from the analysis of the magneto-conductance Δσ = σ(H) – σ(0) by the sum of AL, MT and the localization terms, where the first, second and third terms correspond to the rate due to the superconducting fluctuation effect, electron-electron and electron-phonon interactions, respectively. The R sq N dependence of δ is expressed by δ = δ0 + αR sq N, where the first term δ0 due to 1/τe-ph (T) and the second term due to the sum of 1/τfluc(T) and 1/τe-e(T). Although we obtained a reasonable value of Debye temperature ΘD ≈630 K from the δ0, the magnitude of the α is about 5 times larger than the theoretical value.

  11. Imaging the electron-boson coupling in superconducting FeSe films using a scanning tunneling microscope.

    Science.gov (United States)

    Song, Can-Li; Wang, Yi-Lin; Jiang, Ye-Ping; Li, Zhi; Wang, Lili; He, Ke; Chen, Xi; Hoffman, Jennifer E; Ma, Xu-Cun; Xue, Qi-Kun

    2014-02-07

    Scanning tunneling spectroscopy has been used to reveal signatures of a bosonic mode in the local quasiparticle density of states of superconducting FeSe films. The mode appears below Tc as a "dip-hump" feature at energy Ω∼4.7kBTc beyond the superconducting gap Δ. Spectra on strained regions of the FeSe films reveal simultaneous decreases in Δ and Ω. This contrasts with all previous reports on other high-Tc superconductors, where Δ locally anticorrelates with Ω. A local strong coupling model is found to reconcile the discrepancy well, and to provide a unified picture of the electron-boson coupling in unconventional superconductors.

  12. The fabrication of YBCO superconductor polycrystalline powder by CCSO

    International Nuclear Information System (INIS)

    Martirosyan, K S; Luss, D; Galstyan, E; Xue, Y Y

    2008-01-01

    We present a novel, cost-effective and simple method to produce polycrystalline superconductor YBa 2 Cu 3 O 7-δ (YBCO) powder by a self-sustaining one-step process called carbon combustion synthesis of oxides (CCSO). In this process the exothermic oxidation of carbon nanoparticles generates a thermal wave that propagates at a velocity of about 1 mm s -1 through the solid yttrium, barium, and copper precursors, converting them rapidly (in the order of seconds) to polycrystalline YBCO. The carbon is not incorporated in the product and is emitted as carbon dioxide (CO 2 ) from the sample, generating a highly porous (∼70%) and friable product. Most of the grains have a plate-like shape, are well connected, and have a size of between 1 and 3 μm. The concentration of the residual carbon was less than 0.06 wt%. The magnetization of as-synthesized samples (without external post-annealing in oxygen), as determined by a SQUID magnetometer, showed an onset of the superconducting (SC) transition at ∼91 K, with a 44% shielding fraction of the -1/(4π) value

  13. Plasma-assisted MOCVD growth of superconducting NbN thin films using Nb dialkylamide and Nb alkylimide precursors

    International Nuclear Information System (INIS)

    Liu Xiang; Ott, A.W.; Chang, R.P.H.; Babcok, J.R.; Belot, J.A.; Metz, M.V.; Marks, T.J.; Lane, M.A.; Kannewurf, C.R.

    2001-01-01

    The first example of the use of metal-organic precursors for depositing NbN superconducting thin films is described. The study, which employed niobium(IV) and niobium(V) pulsed source precursors and hydrazine plasma as the nitrogen source, indicates that T c is highly dependent on the lattice parameters and level of oxygen impurities, which are in turn governed by growth and post-deposition annealing temperatures. (orig.)

  14. Interpretation of transmission through type II superconducting thin film on dielectric substrate as observed by laser thermal spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Šindler, Michal; Tesař, Roman; Koláček, Jan; Skrbek, L.

    2012-01-01

    Roč. 483, DEC (2012), s. 127-135 ISSN 0921-4534 R&D Projects: GA ČR(CZ) GAP204/11/0015 Grant - others:European Science Foundation(XE) NES, 2007 - 2012 Institutional research plan: CEZ:AV0Z10100521 Keywords : far- infrared transmission * NbN * superconducting film * vortices * terahertz waves Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.718, year: 2012

  15. Study by Hall probe mapping of the trapped flux modification produced by local heating in YBCO HTS bulks for different surface/volume ratios

    International Nuclear Information System (INIS)

    Laurent, Ph; Mathieu, J-P; Mattivi, B; Fagnard, J-F; Meslin, S; Noudem, J G; Ausloos, M; Cloots, R; Vanderbemden, Ph

    2005-01-01

    The aim of this report is to compare the trapped field distribution under a local heating created at the sample edge for different sample morphologies. Hall probe mappings of the magnetic induction trapped in YBCO bulk samples maintained out of thermal equilibrium were performed on YBCO bulk single domains, YBCO single domains with regularly spaced hole arrays, and YBCO superconducting foams. The capability of heat draining was quantified by two criteria: the average induction decay and the size of the thermally affected zone caused by a local heating of the sample. Among the three investigated sample shapes, the drilled single domain displays a trapped induction which is weakly affected by the local heating while displaying a high trapped field. Finally, a simple numerical modelling of the heat flux spreading into a drilled sample is used to suggest some design rules about the hole configuration and their size

  16. Research on resistance characteristics of YBCO tape under short-time DC large current impact

    Science.gov (United States)

    Zhang, Zhifeng; Yang, Jiabin; Qiu, Qingquan; Zhang, Guomin; Lin, Liangzhen

    2017-06-01

    Research of the resistance characteristics of YBCO tape under short-time DC large current impact is the foundation of the developing DC superconducting fault current limiter (SFCL) for voltage source converter-based high voltage direct current system (VSC-HVDC), which is one of the valid approaches to solve the problems of renewable energy integration. SFCL can limit DC short-circuit and enhance the interrupting capabilities of DC circuit breakers. In this paper, under short-time DC large current impacts, the resistance features of naked tape of YBCO tape are studied to find the resistance - temperature change rule and the maximum impact current. The influence of insulation for the resistance - temperature characteristics of YBCO tape is studied by comparison tests with naked tape and insulating tape in 77 K. The influence of operating temperature on the tape is also studied under subcooled liquid nitrogen condition. For the current impact security of YBCO tape, the critical current degradation and top temperature are analyzed and worked as judgment standards. The testing results is helpful for in developing SFCL in VSC-HVDC.

  17. Preparation of Superconductor YBCO-123/Ag Composite Through Urea Molten Salt

    International Nuclear Information System (INIS)

    Yustinus, P.; Indra-Gunawan; Wuryanto

    1996-01-01

    Superconductor YBCO-123/Ag composite has been prepared through Urea molten salt by mixing salt nitrate of Yttrium, Barium, Copper and Silver. The weight of Silver content varied from 0 % - 50 %. After pyrolysis process the powder was subjected to calcination at 300, 500 and 700 o C subsequently for 1 hour. The calcined powders was pelletized into a disk of 1.0 cm in diameter and thickness of 2-3 mm. Sintering of pellet samples was done at 900 o C for 16 hours. Meissner effect on all samples displayed superconductivity phenomena. Samples were examined by XRD, SEM, measurement of critical temperature by using susceptibility magnet vs temperature, and critical current density measurement by using four point probe. Based on orthorhombic structure of YBCO-123 the result of the lattice crystal calculation were is a = 3.8167 - 3.8241 A o ; b = 3.8561 - 3.8895 A o and c = 11.6518 - 11.7104 A o , this showed that silver did not influence the structure of YBCO. Superconductor YBCO-123/Ag composite was prepared. This was proved by critical current density. Jc data which showed increased with increasing of silver content and the highest result was 9.71 x 10 5 Amp/m 2

  18. Layer-by-layer deposition of superconducting Sr-Ca-Cu-O films by the spray pyrolysis technique

    International Nuclear Information System (INIS)

    Pawar, S.H.; Pawaskar, P.N.; Ubale, M.J.; Kulkarni, S.B.

    1995-01-01

    Layer-by-layer deposition of Sr-Ca-Cu-O films has been carried out using the spray pyrolysis technique. Reagent-grade nitrates of strontium, calcium and copper were used to prepare starting solutions for spray pyrolysis. A two-step procedure was used for every layer of the constituents in the sequence Sr-Cu-Ca-Cu-Sr: first, deposition onto silver substrate at 350 C, then firing at T≥450 C, both at atmospheric pressure. The films were 2-3 μm thick and showed adequate adhesion to the substrate. The films were then characterised by studying their electron micrographs, X-ray diffraction patterns and electrical resistivity. The films showed superconductivity below 104 K. ((orig.))

  19. Magnetic-field dependence of electrothermal conductivity in YBCO

    Energy Technology Data Exchange (ETDEWEB)

    Marino, A.; Uribe, R. [Universidad del Tolima, Ibague (Colombia); Grupo de Superconductividad y Nuevos Materiales, Universidad Nacional de Colombia, Bogota (Colombia)

    2008-11-15

    Experimental measurements of the electrothermal conductivity (P) near T{sub c}, as a function of external magnetic field were carried out in undoped YBCO (123) superconducting samples. The electrothermal conductivity which relates electrical and thermal currents, depends on the applied magnetic field in high T{sub c} materials, contrary to conventional low T{sub c} superconductors where P is nearly independent of the magnetic field. The experimental P(B,T) data determined from resistivity and thermopower measurements were analyzed in terms of theoretical models and showed a behavior consistent with an order-parameter symmetry (OPS) of d{sub x{sup 2}-y{sup 2}}-wave type. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  20. Pinning Mechanisms in YBCO Tapes

    CERN Document Server

    Spera, Marcello; Ballarino, Amalia

    2015-01-01

    In this thesis work, a study on flux pinning mechanisms of commercial YBCO tapes is presented. This study has been performed via critical current characterization using transport (via direct I-V curves) and magnetization (via a Vibrating Sample Magnetometer) measurements. The latter ones turned out to be better concerning the comprehension of the pinning landscape of the provided samples, as a wider range of magnetic fields and temperatures is available for those measurements in the setup I used. The comparison of the experimental data with existing theoretical models allowed me to draw a picture of the pinning mechanisms underlying in each sample, and they turned out to be quite different one another. Moreover, for high-performance research tapes, another interesting feature has been found: the counterplay between the self-field critical current and the in-field one. Very well engineered artificial pinning structures limit the self-field critical current density due to the hi...

  1. Probing the phase diagram of cuprates with YBa2Cu3O7 -δ thin films and nanowires

    Science.gov (United States)

    Arpaia, Riccardo; Andersson, Eric; Trabaldo, Edoardo; Bauch, Thilo; Lombardi, Floriana

    2018-02-01

    We have grown and characterized 30-nm-thick YBa2Cu3O7 -δ (YBCO) films, deposited by pulsed laser deposition on both MgO (110) and SrTiO3 (001) substrates, which induce opposite strain to the superconducting layer. By carefully tuning the in situ post-annealing oxygen pressure, we achieved, in a reproducible way, films at different oxygen doping, spanning from the slightly overdoped down to the strongly underdoped region of the phase diagram. The transport properties of the films, investigated through resistance versus temperature measurements, are in perfect qualitative agreement with single crystals. Starting from these films, we have also successfully fabricated nanowires with widths down to 65 nm, at different oxygen doping. The nanostructures exhibit characteristic temperatures (as the critical temperature Tc and the pseudogap temperature T*) similar to those of the as-grown films and carry critical current densities Jc close to the critical depairing value, limited by vortex entry. This implies that the superconducting and the normal state properties of underdoped YBCO are preserved in our films, and they can be studied as a function of the dimensionality of the system, down to the nanoscale.

  2. Superconducting properties of YBa2Cu3O7−δ films deposited on commercial tape substrates, decorated with Pd or Ta nano-islands

    International Nuclear Information System (INIS)

    Polat, Ö; Thompson, J R; Leonard, K J; Wee, S H; Christen, D K; Ertuğrul, M; Sinclair, J W; Zuev, Y L; Paranthaman, M P; Aytuğ, T; Xiong, X; Selvamanickam, V

    2012-01-01

    To obtain an engineered surface for deposition of high-T c superconductors, nanoscale modulations of the surface of the underlying LaMnO 3 (LMO) cap layer is a potential source for generating microstructural defects in YBa 2 Cu 3 O 7−δ (YBCO) films. These defects may improve the flux pinning and consequently increase the critical current density, J c . To provide such nanoscale modulation via a practical and scalable process, palladium (Pd) or tantalum (Ta) nano-islands were deposited using dc-magnetron sputtering on the surface of the cap layer of commercial metal tape templates for second-generation wires. The size and density of these nano-islands can be controlled by changing sputtering conditions such as the power and deposition time. Compared to the reference sample grown on an untreated LMO cap layer, the YBCO films grown on the LMO cap layers with Pd or Ta nano-islands exhibited improved in-field J c performance. Atomic force microscopy and transmission electron microscopy were used to assess the evolving size and density of the nano-islands. (paper)

  3. Low-frequency noise in high-Tc superconducting thick films

    International Nuclear Information System (INIS)

    Aponte, J.M.; Gutierrez, G.; Octavio, M.

    1990-01-01

    In this paper experimental results on the resistance noise in thick films of YBa 2 Cu 3 O 7-δ in the vicinity of the superconducting transition are reported. The measurements were performed in samples with broad resistive transitions and in the frequency range from 1Hz to 100 Hz. The power spectral density S v /V 2 of the excess noise is obtained by subtracting the current-independent background noise from the total measured noise. The authors observed that at the transition, the magnitude of S v /V 2 rises above its level at room temperature exhibiting peaks at the same temperatures at which R -1 dR/dT has maxima. The authors performed measurements of S v /V 2 as a function of the current through the sample and the authors found that it diverges as the critical current is approached from above and that it is zero below the critical current. This transition is found to be described quite well by a percolation model

  4. Quantum dynamics of small Josephson junctions: an application to superconductivity in granular films

    International Nuclear Information System (INIS)

    Fisher, M.P.A.

    1986-01-01

    This thesis is devoted to a study of the quantum dynamics of small Josephson junctions. Of interest are those features of the junction's behavior which depend explicitly on the quantum mechanical nature of the phase difference phi between the superconductors. In Chapters I and II several calculations are described which focus on the junction's DC resistance. A fully quantum mechanical Hamiltonian is employed that incorporates the dissipative effects due to the unpaired electrons by coupling to a bath of harmonic oscillators. It is shown that the model exhibits a novel zero temperature phase transition as a function of the strength of the dissipation. In the low dissipation regime the phase is free to tunnel quantum mechanically and the junction's resistance is finite; in response to an external current, tunnelling induces successive 2π phase slips leading to a finite voltage state. In contrast, in the high dissipation regime, tunnelling is suppressed and the junction behaves as a superconductor carrying current with no resistive losses. In Chapters III and IV, these results are applied in an attempt to explain the recent observation that in ultra thin Sn films there is apparently a universal normal state sheet resistance above which superconductivity cannot be established

  5. Phonon-induced enhancement of the energy gap and critical current of superconducting aluminum films

    International Nuclear Information System (INIS)

    Seligson, D.; Clarke, J.

    1983-01-01

    Enhancements of the energy gap Δ and the critical current I/sub c/ have been induced in thin superconducting aluminum films near the transition temperature T/sub c/ by pulses of phonons at approximately 9 GHz. In terms of the change in temperature Vertical BardeltaT/T/sub c/Vertical Bar necessary to produce the same enhancement in equilibrium, the gap enhancement increased smoothly with phonon power at fixed temperature and decreasing temperature at fixed phonon power; however, very close to T/sub c/ the enhancement rolled off. At relatively low phonon powers, the data were in good agreement with the theory of Eckern, Schmid, Schmutz, and Schoen, but at higher power levels the data fell markedly below the predictions of the theory. The critical-current enhancements in terms of Vertical BardeltaT/T/sub c/Vertical Bar were always larger than the gap enhancements at the same temperature and phonon power. At fixed phonon power the critical-current enhancements were nearly independent of temperature, except very close to T/sub c/ where the enhancement became small. The inclusion of the nonequilibrium quasiparticle distribution and the kinetic energy of the supercurrent in the theory relating the critical-current enhancement to the gap enhancement did not resolve the discrepancies between the two enhancements. It appears likely that there is an additional mechanism for critical-current enhancement that has not yet been identified

  6. Mixed pinning landscape in nanoparticle-introduced YGdBa2Cu3Oy films grown by metal organic deposition

    Science.gov (United States)

    Miura, M.; Maiorov, B.; Baily, S. A.; Haberkorn, N.; Willis, J. O.; Marken, K.; Izumi, T.; Shiohara, Y.; Civale, L.

    2011-05-01

    We study the field (H) and temperature (T) dependence of the critical current density (Jc) and irreversibility field (Hirr) at different field orientations in Y0.77Gd0.23Ba2Cu3Oy with randomly distributed BaZrO3 nanoparticles (YGdBCO+BZO) and YBa2Cu3Oy (YBCO) films. Both MOD films have large RE2Cu2O5 (225) nanoparticles (˜80 nm in diameter) and a high density of twin boundaries (TB). In addition, YGdBCO+BZO films have a high density of BZO nanoparticles (˜25 nm in diameter). At high temperatures (T > 40 K), the superconducting properties, such as Jc, Hirr, and flux creep rates, are greatly affected by the BZO nanoparticles, while at low temperatures the superconducting properties of both the YBCO and YGdBCO+BZO films show similar field and temperature dependencies. In particular, while the Jc of YBCO films follow a power-law dependence (∝H-α) at all measured T, this dependence is only followed at low T for YGdBCO+BZO films. As a function of T, the YGdBCO+BZO film shows Jc(T,0.01T)~[1-(T/Tc)2]n with n ˜ 1.24 ± 0.05, which points to “δTc pinning.” We analyze the role of different types of defects in the different temperature regimes and find that the strong pinning of the BZO nanoparticles yields a higher Hirr and improved Jc along the c axis and at intermediate orientations at high T. The mixed pinning landscapes due to the presence of disorder of various dimensionalities have an important role in the improvement of in-field properties.

  7. Transport ac loss studies of YBCO coated conductors with nickel alloy substrates

    International Nuclear Information System (INIS)

    Duckworth, R C; Thompson, J R; Gouge, M J; Lue, J W; Ijaduola, A O; Yu, D; Verebelyi, D T

    2003-01-01

    Transport alternating current (ac) loss measurements were performed on a series of rolling-assisted biaxially textured substrate (RABiTS) processed YBa 2 Cu 3 O x (YBCO) coated conductors at 77 K. While each sample possessed a 1 μm layer of YBCO and a 3 μm silver cap layer, two different nickel alloy substrates were used and their impact on the ac loss was examined. Both substrates possessed a 75 μm Ni-5 at%W base, but one substrate also had a 2 μm nickel overlayer as part of the buffer layer architecture. The ac losses, which were determined by thermal and electrical measurements, contained two dominant contributions: superconductive hysteresis in the YBCO and ferromagnetic hysteresis in the substrates. The superconductive component followed the Norris elliptic model for the substrate with the nickel overlayer and the Norris thin strip model for the substrate without the nickel overlayer. The substrates' ferromagnetic loss was determined separately through magnetization measurements, which showed that this loss contribution was independent of the presence of the nickel overlayer for effective ac currents less than 50 A. While the overall loss was lower for the thin-strip-like conductor with no nickel overlayer, further research is necessary to strengthen this connection

  8. Magnetic levitation and its application for education devices based on YBCO bulk superconductors

    International Nuclear Information System (INIS)

    Yang, W.M.; Chao, X.X.; Guo, F.X.; Li, J.W.; Chen, S.L.

    2013-01-01

    Highlights: • A small superconducting maglev propeller system has been designed and constructed based on YBCO bulk superconductors. • Several small maglev vehicle models have been designed and constructed based on YBCO bulk superconductors. • The models can be used as experimental or demonstration devices for the magnetic levitation applications. -- Abstract: A small superconducting maglev propeller system, a small spacecraft model suspending and moving around a terrestrial globe, several small maglev vehicle models and a magnetic circuit converter have been designed and constructed. The track was paved by NdFeB magnets, the arrangement of the magnets made us easy to get a uniform distribution of magnetic field along the length direction of the track and a high magnetic field gradient in the lateral direction. When the YBCO bulks mounted inside the vehicle models or spacecraft model was field cooled to LN 2 temperature at a certain distance away from the track, they could be automatically floating over and moving along the track without any obvious friction. The models can be used as experimental or demonstration devices for the magnetic levitation applications

  9. Magnetic levitation and its application for education devices based on YBCO bulk superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Yang, W.M., E-mail: yangwm@snnu.edu.cn; Chao, X.X.; Guo, F.X.; Li, J.W.; Chen, S.L.

    2013-10-15

    Highlights: • A small superconducting maglev propeller system has been designed and constructed based on YBCO bulk superconductors. • Several small maglev vehicle models have been designed and constructed based on YBCO bulk superconductors. • The models can be used as experimental or demonstration devices for the magnetic levitation applications. -- Abstract: A small superconducting maglev propeller system, a small spacecraft model suspending and moving around a terrestrial globe, several small maglev vehicle models and a magnetic circuit converter have been designed and constructed. The track was paved by NdFeB magnets, the arrangement of the magnets made us easy to get a uniform distribution of magnetic field along the length direction of the track and a high magnetic field gradient in the lateral direction. When the YBCO bulks mounted inside the vehicle models or spacecraft model was field cooled to LN{sub 2} temperature at a certain distance away from the track, they could be automatically floating over and moving along the track without any obvious friction. The models can be used as experimental or demonstration devices for the magnetic levitation applications.

  10. Depairing critical current achieved in superconducting thin films with through-thickness arrays of artificial pinning centers

    International Nuclear Information System (INIS)

    Dinner, Rafael B; Wimbush, Stuart C; MacManus-Driscoll, Judith L; Blamire, Mark G; Robinson, Adam P

    2011-01-01

    Large area arrays of through-thickness nanoscale pores have been milled into superconducting Nb thin films via a process utilizing anodized aluminum oxide thin film templates. These pores act as artificial flux pinning centers, increasing the superconducting critical current, J c , of the Nb films. By optimizing the process conditions including anodization time, pore size and milling time, J c values approaching and in some cases matching the Ginzburg-Landau depairing current of 30 MA cm -2 at 5 K have been achieved-a J c enhancement over as-deposited films of more than 50 times. In the field dependence of J c , a matching field corresponding to the areal pore density has also been clearly observed. The effect of backfilling the pores with magnetic material has then been investigated. While backfilling with Co has been successfully achieved, the effect of the magnetic material on J c has been found to be largely detrimental compared to voids, although a distinct influence of the magnetic material in producing a hysteretic J c versus applied field behavior has been observed. This behavior has been tested for compatibility with currently proposed models of magnetic pinning and found to be most closely explained by a model describing the magnetic attraction between the flux vortices and the magnetic inclusions.

  11. Roughness analysis applied to niobium thin films grown on MgO(001) surfaces for superconducting radio frequency cavity applications

    Science.gov (United States)

    Beringer, D. B.; Roach, W. M.; Clavero, C.; Reece, C. E.; Lukaszew, R. A.

    2013-02-01

    This paper describes surface studies to address roughness issues inherent to thin film coatings deposited onto superconducting radio frequency (SRF) cavities. This is particularly relevant for multilayered thin film coatings that are being considered as a possible scheme to overcome technical issues and to surpass the fundamental limit of ˜50MV/m accelerating gradient achievable with bulk niobium. In 2006, a model by Gurevich [Appl. Phys. Lett. 88, 012511 (2006)APPLAB0003-695110.1063/1.2162264] was proposed to overcome this limit that involves coating superconducting layers separated by insulating ones onto the inner walls of the cavities. Thus, we have undertaken a systematic effort to understand the dynamic evolution of the Nb surface under specific deposition thin film conditions onto an insulating surface in order to explore the feasibility of the proposed model. We examine and compare the morphology from two distinct Nb/MgO series, each with its own epitaxial registry, at very low growth rates and closely examine the dynamical scaling of the surface features during growth. Further, we apply analysis techniques such as power spectral density to the specific problem of thin film growth and roughness evolution to qualify the set of deposition conditions that lead to successful SRF coatings.

  12. Roughness analysis applied to niobium thin films grown on MgO(001 surfaces for superconducting radio frequency cavity applications

    Directory of Open Access Journals (Sweden)

    D. B. Beringer

    2013-02-01

    Full Text Available This paper describes surface studies to address roughness issues inherent to thin film coatings deposited onto superconducting radio frequency (SRF cavities. This is particularly relevant for multilayered thin film coatings that are being considered as a possible scheme to overcome technical issues and to surpass the fundamental limit of ∼50  MV/m accelerating gradient achievable with bulk niobium. In 2006, a model by Gurevich [Appl. Phys. Lett. 88, 012511 (2006APPLAB0003-695110.1063/1.2162264] was proposed to overcome this limit that involves coating superconducting layers separated by insulating ones onto the inner walls of the cavities. Thus, we have undertaken a systematic effort to understand the dynamic evolution of the Nb surface under specific deposition thin film conditions onto an insulating surface in order to explore the feasibility of the proposed model. We examine and compare the morphology from two distinct Nb/MgO series, each with its own epitaxial registry, at very low growth rates and closely examine the dynamical scaling of the surface features during growth. Further, we apply analysis techniques such as power spectral density to the specific problem of thin film growth and roughness evolution to qualify the set of deposition conditions that lead to successful SRF coatings.

  13. Roughness analysis applied to niobium thin films grown on MgO(001) surfaces for superconducting radio frequency cavity applications

    Energy Technology Data Exchange (ETDEWEB)

    Beringer, D. B. [College of William and Mary, Williamsburg, VA (United States). Dept. of Physics; Roach, W. M. [College of William and Mary, Williamsburg, VA (United States). Dept. of Applied Science; Clavero, C. [College of William and Mary, Williamsburg, VA (United States). Dept. of Applied Science; Reece, C. E. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Lukaszew, R. A. [College of William and Mary, Williamsburg, VA (United States). Dept. of Physics; College of William and Mary, Williamsburg, VA (United States). Dept. of Applied Science

    2013-02-05

    This paper describes surface studies to address roughness issues inherent to thin film coatings deposited onto superconducting radio frequency (SRF) cavities. This is particularly relevant for multilayered thin film coatings that are being considered as a possible scheme to overcome technical issues and to surpass the fundamental limit of ~500 MV/m accelerating gradient achievable with bulk niobium. In 2006, a model by Gurevich [ Appl. Phys. Lett. 88 012511 (2006)] was proposed to overcome this limit that involves coating superconducting layers separated by insulating ones onto the inner walls of the cavities. Thus, we have undertaken a systematic effort to understand the dynamic evolution of the Nb surface under specific deposition thin film conditions onto an insulating surface in order to explore the feasibility of the proposed model. We examine and compare the morphology from two distinct Nb/MgO series, each with its own epitaxial registry, at very low growth rates and closely examine the dynamical scaling of the surface features during growth. Further, we apply analysis techniques such as power spectral density to the specific problem of thin film growth and roughness evolution to qualify the set of deposition conditions that lead to successful SRF coatings.

  14. Optimization of cathodic arc deposition and pulsed plasma melting techniques for growing smooth superconducting Pb photoemissive films for SRF injectors

    Science.gov (United States)

    Nietubyć, Robert; Lorkiewicz, Jerzy; Sekutowicz, Jacek; Smedley, John; Kosińska, Anna

    2018-05-01

    Superconducting photoinjectors have a potential to be the optimal solution for moderate and high current cw operating free electron lasers. For this application, a superconducting lead (Pb) cathode has been proposed to simplify the cathode integration into a 1.3 GHz, TESLA-type, 1.6-cell long purely superconducting gun cavity. In the proposed design, a lead film several micrometres thick is deposited onto a niobium plug attached to the cavity back wall. Traditional lead deposition techniques usually produce very non-uniform emission surfaces and often result in a poor adhesion of the layer. A pulsed plasma melting procedure reducing the non-uniformity of the lead photocathodes is presented. In order to determine the parameters optimal for this procedure, heat transfer from plasma to the film was first modelled to evaluate melting front penetration range and liquid state duration. The obtained results were verified by surface inspection of witness samples. The optimal procedure was used to prepare a photocathode plug, which was then tested in an electron gun. The quantum efficiency and the value of cavity quality factor have been found to satisfy the requirements for an injector of the European-XFEL facility.

  15. Vortex pinning vs superconducting wire network: origin of periodic oscillations induced by applied magnetic fields in superconducting films with arrays of nanomagnets

    International Nuclear Information System (INIS)

    Gomez, A; Del Valle, J; Gonzalez, E M; Vicent, J L; Chiliotte, C E; Carreira, S J; Bekeris, V; Prieto, J L; Schuller, Ivan K

    2014-01-01

    Hybrid magnetic arrays embedded in superconducting films are ideal systems to study the competition between different physical (such as the coherence length) and structural length scales such as are available in artificially produced structures. This interplay leads to oscillation in many magnetically dependent superconducting properties such as the critical currents, resistivity and magnetization. These effects are generally analyzed using two distinct models based on vortex pinning or wire network. In this work, we show that for magnetic dot arrays, as opposed to antidot (i.e. holes) arrays, vortex pinning is the main mechanism for field induced oscillations in resistance R(H), critical current I c (H), magnetization M(H) and ac-susceptibility χ ac (H) in a broad temperature range. Due to the coherence length divergence at T c , a crossover to wire network behaviour is experimentally found. While pinning occurs in a wide temperature range up to T c , wire network behaviour is only present in a very narrow temperature window close to T c . In this temperature interval, contributions from both mechanisms are operational but can be experimentally distinguished. (papers)

  16. Development of a 20kA current feedthrough using YBCO bulk conductors

    International Nuclear Information System (INIS)

    Maehata, Keisuke; Ishibashi, Kenji; Shintomi, Takakazu; Iwamoto, Akifumi; Maekawa, Ryuji; Mito, Toshiyuki

    2004-01-01

    In the phase II experiment of the Large Helical Device (LHD) of the National Institute for Fusion Science (NIFS), it is planned to operate the helical coils at 1.8 K by employing pressurized superfluid cooling to raise the magnetic field to 4 T with 17.3 kA. It is important to develop a 20kA-class current feedthrough into the 1.8 K region, but it must have a high current capacity and low heat leakage in the maximum magnetic leakage field of 1 T. Rectangle-shaped YBCO bulk conductors measuring 20 mm wide, 140 mm long and 10 mm thick were manufactured from square-pillar-shaped YBCO bulk materials for a 20 kA current. To check the quality of the bulk conductors, internal defects or cracks were detected by carrying out a precise survey of trapped magnetic flux. An assembled 20 kA current feedthrough was mounted in the λ-plate of a pressurized superfluid cooling cryostat. Experiments of current feeding into the 1.8 K region were carried out by operating the 20 kA current feedthrough. In the experiments, the transport current was kept at 20 kA for longer than 1,200 s. During the 20 kA operation, the current transport section of the YBCO bulk conductors remained in the superconducting state and the voltage drop between the YBCO bulk conductors and the copper electrode was observed to be constant. A contact resistance and the Joule heat generation in the joint region between the YBCO bulk conductors and the copper electrode were obtained as 1.45 nΩ and 0.72 W, respectively in the 20 kA operation. We have demonstrated the feasibility of using a 20 kA current feedthrough for the phase II experiment of the LHD. (author)

  17. Study of microstructure and electrical properties of bulk YBCO prepared by melt textured growth technique

    International Nuclear Information System (INIS)

    Gonal, M. R.; Krishnan, Madangopal; Tewari, R.; Tyagi, A. K.; Gyore, A.; Vajda, I.

    2015-01-01

    Bulk YBCO components were prepared using Melt Texture Growth (MTG) technique. Components were fabricated using MTG by addition of Y 2 BaCuO 5 (Y211) and Ag to YBCO, which leads to improved grain size without affecting superconducting properties. Green compacts prepared by cold isostatic pressing were pre-sintered at 930°C before subjecting melt texturing. Cooling rates lower than 1 °C.h −1 was used, in between (peritectic) temperature of about 995 and 1025°C, to obtain large grained components. Microstructure studies in details were carried out by Scanning Electron Microscope (SEM), Electron Probe Micro Analysis (EPMA), Orientation Imaging Microscope (OIM) and TEM correlated with electrical properties like Critical current density (J c )

  18. Static Test for a Gravitational Force Coupled to Type 2 YBCO Superconductors

    Science.gov (United States)

    Li, Ning; Noever, David; Robertson, Tony; Koczor, Ron; Brantley, Whitt

    1997-01-01

    As a Bose condensate, superconductors provide novel conditions for revisiting previously proposed couplings between electromagnetism and gravity. Strong variations in Cooper pair density, large conductivity and low magnetic permeability define superconductive and degenerate condensates without the traditional density limits imposed by the Fermi energy (approx. 10(exp -6) g cc. Recent experiments have reported anomalous weight loss for a test mass suspended above a rotating type II, YBCO superconductor, with the percentage change (0.05 - 2.1 %) independent of the test mass' chemical composition and diamagnetic properties. A variation of 5 parts per 10' was reported above a stationary (non-rotating) superconductor. In experiments using a sensitive gravimeter, bulk YBCO superconductors were stably levitated in a DC magnetic field. Changes in acceleration were measured to be less than 2 parts in 108 of the normal gravitational acceleration. This result puts new limits on the strength and range of the proposed coupling between static superconductors and gravity.

  19. Soft X-ray angle-resolved photoemission spectroscopy of heavily boron-doped superconducting diamond films

    Directory of Open Access Journals (Sweden)

    T. Yokoya, T. Nakamura, T. Matushita, T. Muro, H. Okazaki, M. Arita, K. Shimada, H. Namatame, M. Taniguchi, Y. Takano, M. Nagao, T. Takenouchi, H. Kawarada and T. Oguchi

    2006-01-01

    Full Text Available We have performed soft X-ray angle-resolved photoemission spectroscopy (SXARPES of microwave plasma-assisted chemical vapor deposition diamond films with different B concentrations in order to study the origin of the metallic behavior of superconducting diamond. SXARPES results clearly show valence band dispersions with a bandwidth of ~23 eV and with a top of the valence band at gamma point in the Brillouin zone, which are consistent with the calculated valence band dispersions of pure diamond. Boron concentration-dependent band dispersions near the Fermi level (EF exhibit a systematic shift of EF, indicating depopulation of electrons due to hole doping. These SXARPES results indicate that diamond bands retain for heavy boron doping and holes in the diamond band are responsible for the metallic states leading to superconductivity at low temperature. A high-resolution photoemission spectroscopy spectrum near EF of a heavily boron-doped diamond superconductor is also presented.

  20. Dopant rearrangement and superconductivity in Bi2Sr2-xLaxCuO6 thin films under annealing

    International Nuclear Information System (INIS)

    Cancellieri, C; Lin, P H; Ariosa, D; Pavuna, D

    2007-01-01

    By combining x-ray diffraction (XRD), x-ray photoemission spectroscopy (XPS) and AC susceptibility measurements we investigate the evolution of structural and superconducting properties of La-doped Bi-2201 thin films grown by pulsed laser deposition (PLD) under different annealing conditions. We find that the main effect of oxygen annealing is to improve the crystal coherence by enabling La cation migration to the Sr sites. This activates the desired hole doping. Short-time Ar annealing removes the interstitial oxygen between the BiO layers, fine adjusting the effective hole doping. The superconducting critical temperature is consequently enhanced. However, longer annealings result in phase separation and segregation of the homologous compound Bi-1201. We attribute this effect to the loss of Bi during the annealing