High-T C superconductor-normal metal-superconductor Josephson microbridges with high-resistance normal metal linksApplied Physics Letters - Tập 59 Số 9 - Trang 1126-1128 - 1991
R.H. Ono, J. A. Beall, M. W. Cromar, Todd E. Harvey, M.E. Johansson, C. D. Reintsema, D. A. Rudman
We have developed an in situ process for fabricating high transition temperature superconductor-normal metal-superconductor microbridges using a step edge to define the normal metal length. Critical current-normal resistance products over 1 mV have been measured at low temperature in devices with high-resistivity Ag-Au alloy bridges. Results on samples with Ag bridges are compared with the...... hiện toàn bộ
Focused ion beam high T c superconductor dc SQUIDsApplied Physics Letters - Tập 59 Số 2 - Trang 234-236 - 1991
Maurizio Zani, J.A. Luine, R. W. Simon, R.A. Davidheiser
Light-ion irradiation can controllably reduce the critical current density of high-temperature superconductor thin films. Reported here is the behavior of ErBa2Cu3O7 films patterned into microbridge dc superconducting quantum interference device (SQUID) structures and irradiated with a rastered high-energy focused ion beam of 70 nm diameter. The resultant SQUIDs have demonstrated up to 51%...... hiện toàn bộ
High quality YBa2Cu3O7 Josephson junctions made by direct electron beam writingApplied Physics Letters - Tập 63 Số 12 - Trang 1696-1698 - 1993
Sergey K. Tolpygo, S. Shokhor, B. Nadgorny, J.-Y. Lin, M. Gurvitch, A. J. Bourdillon, S. Y. Hou, Julia M. Phillips
High-Tc Josephson junctions have been fabricated by direct electron beam writing over YBa2Cu3O7 thin-film microbridges, using scanning transmission electron microscope (STEM) with an accelerating voltage of 80–120 kV. Annealing at 330–380 K increases Tc and Ic of the junctions and makes them more stable. In the operating range of a few degrees below Tc, the junctions show 100% magnetic fie...... hiện toàn bộ
Optimization of the surface morphology of magnetron-sputtered Y1Ba2Cu3O7−x filmsApplied Physics Letters - Tập 64 Số 23 - Trang 3166-3168 - 1994
J. Auge, Margit Jansen, Hartmut G. Roskos, H. Kurz
We demonstrate that the surface morphology of 20–200-nm-thick magnetron-sputtered Y1Ba2Cu3O7 films can be optimized by careful control of the plasma current. The optimization can be performed at different substrate temperatures allowing us to maximize the transition temperature Tc and the homogeneity of the films independently from the optimization of the surface morphology. This sequence ...... hiện toàn bộ
Substrate step-edge YBa2Cu3O7 rf SQUIDsApplied Physics Letters - Tập 58 Số 5 - Trang 543-545 - 1991
K.P. Daly, W. D. Dozier, J.F. Burch, S.B. Coons, R. Hu, C. E. Platt, R. W. Simon
We have developed a technique which permits high-yield fabrication of microbridges and low noise YBa2Cu3O7 superconducting quantum interference devices (SQUIDs) in epitaxial thin films. These SQUIDs operate over a wide temperature range extending from 4 K to close to the superconducting transition temperature. Measurements of an rf SQUID operating at 77 K give a peak-to-peak flux sensitivi...... hiện toàn bộ
All a-axis oriented YBa2Cu3O7−y-PrBa2Cu3O7−z-YBa2Cu3O7−y Josephson devices operating at 80 KApplied Physics Letters - Tập 59 Số 6 - Trang 742-744 - 1991
J. B. Barner, Charles T. Rogers, A. Inam, R. Ramesh, S. Bersey
We have demonstrated the controllable, reproducible fabrication of nonhysteretic Josephson devices with excess-current weak-link characteristics at temperatures up to 80 K. The devices are patterned from in situ deposited a-axis oriented YBa2Cu3O7−y-PrBa2Cu3O7−z-YBa2Cu3O7−y trilayers grown on SrTiO3(001) substrates. Control of the critical current density and resistance is achieved by vary...... hiện toàn bộ
Practical high T c Josephson junctions and dc SQUIDs operating above 85 KApplied Physics Letters - Tập 58 Số 22 - Trang 2552-2554 - 1991
M. S. Di Iorio, S. Yoshizumi, Keedong Yang, J. Zhang, M. Maung
Reproducible high Tc YBa2Cu3O7/Ag/YBa2Cu3O7 Josephson junctions have been fabricated using an entirely in situ step-edge technique. The junction process requires the deposition of a single high Tc film and the patterning is performed using standard photolithography and ion-beam etching. The junctions exhibit a well-defined supercurrent from 4.2 to 87 K and the ac Josephson effect is observ...... hiện toàn bộ
All high T c edge-geometry weak links utilizing Y-Ba-Cu-O barrier layersApplied Physics Letters - Tập 59 Số 8 - Trang 982-984 - 1991
B. D. Hunt, M. C. Foote, Louis J. Bajuk
High quality YBa2Cu3O7−x/normal-metal/YBa2Cu3O7−x edge-geometry weak links have been fabricated using nonsuperconducting Y-Ba-Cu-O barrier layers deposited by laser ablation at reduced growth temperatures. Devices incorporating 25–100 Å thick barrier layers exhibit current-voltage characteristics consistent with the resistively shunted junction model, with strong microwave and magnetic fie...... hiện toàn bộ
Scaling behavior of YBa2Cu3O7−δ thin-film weak linksApplied Physics Letters - Tập 57 Số 11 - Trang 1155-1157 - 1990
S. E. Russek, D. K. Lathrop, B. H. Moeckly, R. A. Buhrman, Dong Hyuk Shin, J. Silcox
The superconductive weak link properties of microbridges formed in c-axis normal YBa2Cu3O7−δ polycrystalline thin films containing a variable amount of large angle tilt boundaries have been studied. In the low critical current density limit these weak links have current-voltage (I-V) characteristics that are accurately modeled by the resistively shunted junction model. The I-V’s are found ...... hiện toàn bộ
Extension of the bi-epitaxial Josephson junction process to various substratesApplied Physics Letters - Tập 59 Số 17 - Trang 2177-2179 - 1991
K. Char, M. S. Colclough, L. P. Lee, G. Zaharchuk
We report an extension of the bi-epitaxial Josephson junction process that permits the use of a variety of substrate materials and allows junctions to be placed at any level of a multilayer structure. The new materials, SrTiO3, MgO, and CeO2, serve as a base layer, a seed layer, and a buffer layer, respectively, and replace Al2O3, MgO, and SrTiO3 in the original bi-epitaxial process. This ...... hiện toàn bộ