A5088344024- Physics of Superconductivity and Magnetism
- Advanced Condensed Matter Physics
- Superconductivity in MgB2 and Alloys
- Magnetic and transport properties of perovskites and related materials
- Iron-based superconductors research
- Superconducting Materials and Applications
- Theoretical and Computational Physics
- Magnetic properties of thin films
- Rare-earth and actinide compounds
- ZnO doping and properties
- Multiferroics and related materials
- Magnetic confinement fusion research
- High-pressure geophysics and materials
- Particle accelerators and beam dynamics
- Magnetic Properties and Applications
- HVDC Systems and Fault Protection
- Electronic and Structural Properties of Oxides
- Semiconductor materials and devices
- Magnetic Properties of Alloys
- Copper Interconnects and Reliability
- Metal and Thin Film Mechanics
- Inorganic Chemistry and Materials
- Magnetic Properties and Synthesis of Ferrites
- Ferroelectric and Piezoelectric Materials
- Crystallization and Solubility Studies
Los Alamos National Laboratory
2014-2023
The University of Tokyo
2014
Brookhaven National Laboratory
2012
Los Alamos Medical Center
2010
Physical Sciences (United States)
2008
Bariloche Atomic Centre
1995-2007
Balseiro Institute
1988-2004
Leonardo (United Kingdom)
2002-2004
Comisión Nacional de Energía Atómica
1983-2002
Universidad Nacional de Cuyo
1983-2000
We report the realization of a microstructure which leads to very strong high-temperature flux pinning in ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$ crystals. Aligned discontinuous columns damaged material, about 50 \AA{} diameter and more than 15 \ensuremath{\mu}m long, are produced by 580-MeV Sn-ion irradiation. The enhancement is largest when applied magnetic field aligned with these tracks. At high temperatures fields much greater that random point defects, causes...
Flux pinning in Y-Ba-Cu-O crystals is studied as a function of fluence 3-MeV protons, which create random local defects. Order-of-magnitude increases the critical current density are deduced from magnetic hysteresis loops, with values up to 2\ifmmode\times\else\texttimes\fi{}${10}^{5}$ A/${\mathrm{cm}}^{2}$ observed at 77 K and 1 T. However, irreversibility line field-temperature plane potentials flux-creep studies hardly changed. These results compared melting models.
A simple theoretical model is proposed for the reversible magnetization of type-II superconductors as a function applied field H entire region between ${\mathit{H}}_{\mathit{c}1}$ and ${\mathit{H}}_{\mathit{c}2}$. For H\ensuremath{\simeq}${\mathit{H}}_{\mathit{c}1}$, theory reduces to variational model, from which can be accurately computed in Ginzburg-Landau regime. In calculating free energy, we include, addition supercurrent kinetic energy magnetic-field kinetic-energy condensation-energy...
We construct a ``phase diagram'' of the vortex-solid phase Y-Ba-Cu-O single crystals by making first overall connection shape magnetic hysteresis M(H,T) with single-vortex (1D) and collective (3D) pinning regimes. The crossovers between different regimes are visualized drawing contours constant critical current density ${\mathit{J}}_{\mathit{c}}$ in H-T plane. identify transition from 1D to 3D pinning, nonlocal into local behavior vortex bundles regime. A direct correlation M(H)...
We present a comparative study of the angular dependent critical current density in YBa2Cu3O7 films deposited on IBAD MgO and single crystal SrTiO3 substrates. identify three regimes where pinning is dominated by different types correlated uncorrelated defects. show that those are all cases, indicating mechanisms same, but their extension characteristics sample dependent, reflecting quantitative differences texture defect density. In particular, more defective nature turns into an advantage...
Columnar defects introduced by irradiation with very energetic heavy ions are the most effective pinning centres for flux lines in high-temperature superconductors. This correlated disorder generates large increases critical current densities and expansion of irreversible regime various Bi- Tl-based compounds. In single crystals thin films, enhancement is strongly angular-dependent, maximizes when applied magnetic field parallel to amorphous latent tracks. contrast, much more anisotropic Tl-...
Remarkable progress has been made in the development of YBa2Cu3O7−δ (YBCO)-based coated conductors, and problems continuous processing commercially viable tape lengths are being rapidly solved by companies around world. However, current carried these tapes is presently limited to about 100A for a 1-cm-wide tape, this due rapid decrease critical density (Jc) as coating thickness increased. We have now overcome problem separating relatively thin YBCO layers with very CeO2. Using multilayer...
Large enhancements in the critical current density Jc were produced single crystals of high-temperature superconductor Bi2Sr2Ca1Cu2O8 by irradiation with high energy Sn ions. In addition, irreversibility line was moved to considerably higher magnetic fields. contrast analogous studies on Y1Ba2Cu3O7, there little, if any, selective pinning when magnetizing field applied parallel linear, ion-damage-produced tracks.
Abstract High critical current densities ( J c ) in thick films of the Y 1 Ba 2 Cu 3 O 7–δ (YBCO, T ≈ 92 K) superconductor directly depend upon types nanoscale defects and their within films. A major challenge for developing a viable wire technology is to introduce defect structures into YBCO grains film suitable flux pinning tailoring superconducting properties specific, application‐dependent, temperature magnetic field conditions. Concurrently, needs be integrated macroscopically...
We report a sharp melting transition of the Bose glass in YBaCuO crystals with columnar defects installed by irradiation 1 GeV Au ions. The ${\mathit{B}}_{\mathrm{BG}}$(T) is tracked at low fields irreversibility line, which undergoes remarkable abrupt crossover field ${\mathit{B}}_{\mathrm{cr}}$ for vortices aligned columns along c axis. Below ${\mathit{B}}_{\mathrm{cr}}$, upward curvature...
The critical current density (Jc) of hot isostatic pressed (HIPed) MgB2 wires, measured by d.c. transport and magnetization, is compared with that similar wires annealed at ambient pressure. HIPed have a higher Jc than the especially high temperatures magnetic fields, irreversibility field (Hirr). are promising for applications, Jc>106 A/cm2 5 K zero >104 1.5 T 26.5 K, Hirr ~ 17 4 K. improvement attributed to structural defects, which likely source vortex pinning. These observed...
We map a pinning boundary in ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$ crystals with columnar defects via (i) finite large drop of the persistent current J(T), (ii) maximum thermal relaxation rate S(T), and (iii) onset 1/H field dependence J(H). This is consistent ``accommodation'' ${\mathit{B}}^{\mathrm{?}}$(T) proposed by Nelson Vinokur, separating regime vortices well localized on pins from interaction-dominated collective...
Enhanced in-field critical current densities (Jc’s) have been obtained in epitaxial superconducting (RE1,RE2)Ba2Cu3O7−x (RE1=rare-earthion 1, and RE2=rare earth ion 2) films grown on both single crystal buffered metallic substrates. For a constant average RE ionic radius (equal to that of yttrium), there is systematic dependence the Jc size variance, with small, but nonzero, variance being optimum. Compared standard YBa2Cu3O7−x composition, factor two improvement Jc(75.5K) reproducibly...
Temperature-dependent critical current density and normalized flux-creep rate, together with the dependence of vortex pinning energy, were studied in as-grown proton-irradiated Y-Ba-Cu-O crystals. A consistent interpretation is found within collective-pinning or vortex-glass models.
We study the field (H) and temperature ($T$) dependence of critical current density (${J}_{c}$) irreversibility (${H}_{\mathrm{irr}}$) at different orientations in ${\mathrm{Y}}_{0.77}$Gd${}_{0.23}$Ba${}_{2}$Cu${}_{3}$O${}_{y}$ with randomly distributed BaZrO${}_{3}$ nanoparticles (YGdBCO$+$BZO) YBa${}_{2}$Cu${}_{3}$O${}_{y}$ (YBCO) films. Both MOD films have large RE${}_{2}$Cu${}_{2}$O${}_{5}$ (225) (\ensuremath{\sim}80 nm diameter) a high twin boundaries (TB). In addition, YGdBCO$+$BZO BZO...
Second-generation (2G) HTS wires are now being produced routinely in kilometer lengths using Metal Organic Chemical Vapor Deposition (MOCVD) process with critical currents of 300 A/cm. While this achievement is enabling several prototype devices, order to reach a substantial commercial market, the cost-performance metrics 2G need be significantly improved device operating conditions. Zr-doping has been found an effective approach improve in-field current performance MOCVD-based wires. In...
We demonstrate that 3.5-MeV oxygen irradiation can markedly enhance the in-field critical current of commercial 2nd generation superconducting tapes with an exposure time just one second per 0.8 cm2. The speed demonstrated here is now at level required for industrial reel-to-reel post-processing. made on production line samples through protective silver coating and does not require any modification growth process. From TEM imaging, we identify small clusters as main source increased vortex pinning.
A strategy to boost the current-carrying capacity of cuprate superconductors beyond levels attainable with parallel columnar defects was recently proposed. It consists enforcement vortex entanglement by controlled splay columns. We demonstrate validity this suggestion in ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{2}$ single crystals using difference naturally occurring irradiations two ions differing mass and energy. The terminal dispersion columns produced 0.58-GeV...
The angular-dependent critical current density J/sub c/ in YBa/sub 2/Cu/sub 3/O/sub 7/ films grown by pulsed laser deposition exhibit a sharp peak for magnetic field orientations near the ab plane, which arises from combined effects of intrinsic pinning and extended defects parallel to planes. An analysis temperature dependence height width this allows us distinguish both contributions. We find that, film on single crystal substrate, at low fields is due primarily defects, but high it...
The performance of Second Generation (2G) high temperature superconducting wire manufactured by continuous reel-to-reel processes is nearing the 300 A/cm-width (77 K, self field) threshold for commercial power cable applications. 2G manufacturing approach under development at American Superconductor based on combination RABiTS substrate-buffer technology with metal organic deposition (MOD) YBCO layer. capability this process has been demonstrated in multiple 10 meter lengths critical...
We have studied the pinning force ${\mathit{F}}_{\mathit{p}}$(B,T) in ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$ crystals as a function of fluence 3-MeV protons. For given ion-damage level, we could reduce all ${\mathit{F}}_{\mathit{p}}$ data to single reduced field b=B/${\mathit{B}}^{\mathrm{*}}$, where scaling ${\mathit{B}}^{\mathrm{*}}$(T)\ensuremath{\ll}${\mathit{H}}_{\mathit{c}2}$(T) is related irreversibility line. This result rules out possibility matching effects...