A5102707583- Physics of Superconductivity and Magnetism
- Magnetic properties of thin films
- Advanced Condensed Matter Physics
- ZnO doping and properties
- Magneto-Optical Properties and Applications
- Semiconductor materials and devices
- Advanced Electrical Measurement Techniques
- Terahertz technology and applications
- Quantum, superfluid, helium dynamics
- Copper Interconnects and Reliability
- Theoretical and Computational Physics
- Magnetic and transport properties of perovskites and related materials
- Surface and Thin Film Phenomena
- Radiation Detection and Scintillator Technologies
- Particle physics theoretical and experimental studies
- Superconductivity in MgB2 and Alloys
- Molecular Junctions and Nanostructures
- Spectroscopy and Quantum Chemical Studies
- Quantum and electron transport phenomena
- Atomic and Subatomic Physics Research
- Advanced Chemical Physics Studies
- Particle Detector Development and Performance
- Diamond and Carbon-based Materials Research
- Electronic and Structural Properties of Oxides
- Spectroscopy and Laser Applications
Jilin University
2023
Alcatel Lucent (Germany)
1993-1996
AT&T (United States)
1992-1996
National Sun Yat-sen University
1996
State University of New York
1996
Nokia (United States)
1992-1994
Yale University
1994
Stanford University
1993
Hewlett-Packard (United States)
1993
The temperature dependence of the magnetic penetration depth ${\mathrm{Bi}}_{2}$${\mathrm{Sr}}_{2}$${\mathrm{CaCu}}_{2}$${\mathrm{O}}_{8}$ single crystals and ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$ thin films has been measured with a parallel plate resonator technique at microwave frequencies. Both materials show ${\mathit{T}}^{2}$ between 10 25 K, systematic deviations towards flatter below K. We have also calculated real...
High-Tc Josephson junctions have been fabricated by direct electron beam writing over YBa2Cu3O7 thin-film microbridges, using scanning transmission microscope (STEM) with an accelerating voltage of 80–120 kV. Annealing at 330–380 K increases Tc and Ic the makes them more stable. In operating range a few degrees below Tc, show 100% magnetic field modulation critical current, microwave-induced Shapiro steps oscillating according to resistively shunted junction (RSJ) model, RSJ current-voltage...
Ordered arrays of columnar defects have been fabricated by direct electron-beam writing on ${c}_{\ensuremath{\perp}}$-oriented $\mathrm{Ya}{\mathrm{Ba}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7\ensuremath{-}\ensuremath{\delta}}(\mathrm{YBCO})$ thin films. Serving as strong pinning sites, cause a 70% enhancement critical current density ${J}_{c}$ at $T=77$ K in magnetic fields parallel to the $c$ axis. The matching effect force has observed, due commensurability between flux lines and defects....
We have measured the magnetotransmission of thin film samples YB${\mathrm{a}}_{2}$C${\mathrm{u}}_{3}$${\mathrm{O}}_{7}$ in normal state using circularly polarized light at frequencies from 15 to $180{\mathrm{cm}}^{\ensuremath{-}1}$. The magneto-optical signal is consistent with ac Hall effect holes a reduced scattering rate and an enhanced mass compared zero-field transport parameters. This result agrees simple high-frequency extension models which been developed explain anomalous dc high-...
Recent measurements at microwave, terahertz (THz), and infrared frequencies have revealed a peak in ${\mathrm{\ensuremath{\sigma}}}_{1}$ below ${\mathit{T}}_{\mathit{c}}$. Based on our THz measurements, which were performed high quality, single crystal films of YBCO (900 500 \AA{}), we found that features increases amplitude shifts to lower temperatures as frequency changes from 1.2 0.4 THz. Although the quasiparticle relaxation time extracted these results using two-fluid Drude model...
We report heteroepitaxial growth of SrTiO3 on YBa2Cu3O7−x/LaAlO3 substrates by plasma-enhanced metalorganic chemical vapor deposition. X-ray diffraction results indicated that films were epitaxially grown a (001) YBa2Cu3O7−x surface with [100] orientation perpendicular to the surface. The film composition, Sr/Ti molar ratio in range 0.9 1.1, was determined Rutherford backscattering spectrometry and energy dispersive spectroscopy. thickness is 0.1–0.2 μm. epitaxial further evidenced...
Electronic device applications of high-temperature superconducting cuprates require the production patterned thin films that are stable and inert in various processing operating environments; however, rare-earth barium have been shown to decompose water degrade properties a humid atmosphere. The thermodynamics forms driving force for degradation is reviewed. Protective coatings or removable protective can realize many facilitate devices. Diamondlike carbon as well amorphous investigated...
We have studied the precipitates in YBa2Cu3O7−δ(YBCO) thin films grown by BaF2 process pO2=4 Torr and 700 °C. While stoichiometric result BaCuO2 surface precipitates, we found Y2Cu2O5 embedded matrix of same film. Off with Ba/Y<1.5 a precipitate-free but higher abundance film matrix. The estimated densities two favor YBCO This behavior is not explainable terms phase equilibria attributed to kinetic effects. electrical properties degrade as Ba/Y ratio deviates from 2.00.
Pulsed terahertz spectroscopy is used to determine the superfluid response of a YBa2Cu3O7−δ film under both thermal and optical stimulation. The coherent, time-domain technique in novel configuration directly measure complex conductivity versus temperature continuous-wave laser illumination. At 0.6 Tc, shows an identical regardless whether stimulus or optical. This contrasts with behavior at 0.26 where dramatic differences are observed depending on sample heated subjected It suggested that...
An increasing number of high speed digital and other circuit applications require very narrow impulses or rapid pulse edge transitions. Shock wave transmission lines using series shunt Josephson junctions are one way to generate these signals. Using two different temperature superconducting junction processes (step-edge electron beam defined nanobridges), such have been constructed tested at 77 K. with approximately 60 YBaCuO nanobridges, generated steps fall times about 10 ps. With...
Measurements in circularly polarized light from 5 to 28 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ magnetic fields up 9T are reported. The zero field response is independent of temperature for T\ensuremath{\leqslant}30 K clean samples and linear T films irradiated with \ensuremath{\alpha} particles. In the transmission left circular polarization varies linearly 30 right temperature. difference maximum at lowest temperatures corresponding an electron active reverses sign 20 K. These results...
The linewidths of phase-locked, oscillating arrays high temperature superconducting Josephson junctions have been used to estimate such statistical information for several junction processes using a fitting process simulate results. Statistical data from consisting hundred many thousand operating, and at least partially phase locked, 77K are being characterize improve processes. Spreads on critical currents three different processes; step edge, edge SNS electron-beam defined nanobridges,...
The transmission (/spl Jscr/) and phase shift thetav/) of 0.2-1.5 THz radiation have been measured simultaneously on unpatterned, high-quality YBa/sub 2/Cu/sub 3/O/sub 7/ films (T/sub c/=90 K) in the normal superconducting states using a coherent, pulsed, time-domain technique. complex surface impedance has extracted without contacting or patterning /spl Jscr/ thetav/. Above T/sub c/, both real (R/sub s/) imaginary (X/sub parts show metallic radic//spl omega/T dependence with almost equal...
Evolution of a doubly-excited state an endocircular anion.
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We have investigated dc superconducting quantum interference devices (SQUIDs) with loop areas 8 and 64 μm2 made by direct electron beam writing in YBa2Cu3O7−x films thickness 25 50 nm. The SQUIDs maximum peak-to-peak voltage modulation of about 20 μV, which corresponds to the transfer factor dV/dΦ0∼50–60 μV/Φ0 at 30–40 K. By measuring mutual inductance SQUID signal line as a function temperature comparing data numerical calculations two-fluid model, we extracted values London penetration...