Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    High-quality Nb3Sn thin films on sapphire prepared by tin vapor diffusion (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 82 (1997), S. 5021-5023 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Stoichiometric Nb3Sn films on sapphire were prepared with a tin vapor diffusion process from sputtered Nb precursors. The superconductive properties of the precursor and the converted films were measured at 1 kHz and 87 GHz. The nanocrystalline Nb films yielded Tc=7.8–9.3 K, ΔTc=0.05–0.30 K, Jc (4.2 K)=0.8–2.8 MA/cm2, and ρ(Tc)=1–35 μΩ cm, indicating a high sensitivity to granularity and impurities. In contrast, the 0.5–3.0 μm thick and large-grained Nb3Sn films showed reproducibly Tc=18.0 K, ΔTc=0.1 K, Jc (4.2 K)=5–6.5 MA/cm2, and ρ(Tc)=7.7–9.1 μΩ cm. A reduced energy gap Δ/kTc=1.8–2.2 and a penetration depth λ0 (T=0 K)=65–80 nm were deduced from the surface impedance measurements. The residual surface resistance dropped below the sensitivity limit of 0.3 mΩ. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.366372
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Spatially resolved microwave field distribution in YBaCuO disk resonators visualized by laser scanning (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 3447-3449 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The applicability of superconducting films in high-performance microwave devices suffers from inhomogeneous growth and local defects. Therefore we have installed a laser scanning system to visualize with spatial resolution the distribution of the microwave fields in 2-in.-diam YBaCuO disk resonators. The TM310 mode was imaged at a loaded quality factor of 8.3×104 via changes of the resonant frequency at 2.21 GHz and 40 K. The field distribution agreed with a magnetic-wall model, indicating at the contour of the disk fringe fields, but without strong edge enhancement. The data also indicated an inhomogeneous effective microwave penetration depth. The spatial resolution is presently limited to about 2 mm by heat diffusion. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122792
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Nonlinear Power Handling of YBa2Cu3O7−x Films and Microwave Devices (1999)
    Springer
    Journal of superconductivity 12 (1999), S. 343-351 
    Details
    ISSN: 1572-9605
    Keywords: YBa2Cu3O7−x ; power handling ; magnetic and thermal field limitations ; defects ; microwave quenches
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Physical mechanisms which limit the power handling of YBa2Cu3O7−x films and devices are discussed in terms of a quantitative classification scheme. The possible limitations are devided into magnetic or thermal, and global or local in nature. Analytical estimations are compared with measurements of YBa2Cu3O7−x films (Ø = 1″–2″) using a niobium-shielded sapphire resonator at 19 GHz, and disk resonators at 2 GHz. Magnetic effects are found to play an essential role in nonoptimized films in terms of weak-links, and in high-quality films if the lower critical field Bcl is reached. The majority of films and disk resonators appear to suffer from microwave heating. Global heating appears predominantly at CW operation. Local heating results mainly from defects in films of medium quality. Defect-induced quenches are observed at moderate field levels, sometimes resulting in an irreversible degradation of the power handling.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007701332081
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Experimental evaluation of the nonlinear surface resistance of YBa2Cu3O7−x step-edge grain boundary Josephson junctions (1996)
    Springer
    Journal of superconductivity 9 (1996), S. 233-236 
    Details
    ISSN: 1572-9605
    Keywords: Microwave impedance ; microstrip resonator ; Josephson junction ; nonlinear power dissipation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The temperature, microwave current, and dc magnetic field dependencies of the effective surface resistanceR s of YBa2Cu3O7−x grain boundary Josephson junctions have been investigated at 6 GHz. The junctions were prepared on stepped LaAlO3 substrates and incorporated into tapered linear half-wavelength microstrip resonators. The characteristic parameters of the heterogeneous resonator were analyzed theoretically considering the junction as a lumped element of complex impedance. The microwave properties of the junction could then be extracted and related to their characteristic dc transport properties. The critical currentI c of the junction was found to limit the linear power dissipation in the superconducting strip. At microwave currents aboveI c , highly nonlinear microwave losses occurred, which displayed a characteristic magnetic field modulation. At even higher currents,R s saturated at a level corresponding to the normal resistanceR n of the junction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00728308
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Pair and Quasiparticle States of YBa2Cu3O7−x Films Deduced from the Surface Impedance and a Comparison with Nb3Sn (1999)
    Springer
    Journal of superconductivity 12 (1999), S. 129-138 
    Details
    ISSN: 1572-9605
    Keywords: Surface impedance ; residual resistance ; energy gap ; two-band model ; magnetic scattering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Surface impedance data at 19 and 87 GHz of high-quality epitaxial YBCO films on different substrates are compared with data for Nb3Sn films on sapphire in terms of pair and quasiparticle (qp) transport. Surface resistance R s and penetration depth λ of YBCO are strongly affected by temperature dependent qp scattering, which is depressed in films with enhanced lattice strain. All films showed a comparable residual resistance R res(19 GHz)∼90 μΩ constituting a qp reservoir which is likely to be caused by the electronic configuration and by impurities. Subtracting R res from R s (T) revealed activated behavior with a reduced energy gap Δ0/k B T c∼0.9 for a film on sapphire, but power-law behavior for the other films. The penetration depth did not reveal power-law dependences at T≤0.5 ·T c, but was consistent with a reduced energy gap of 0.45 for a film on MgO. The increase of λ(T) at T≥0.5 · T c was related to qp scattering, which also caused an extremal conductivity σ1(T). A shoulder in λ(T) at T=(0.6–0.7) · T c confirmed evidence for the existence of two superconducting bands. The magnetic-field induced recovery of λ(B) of various YBCO films hinted for an important role of magnetic scattering. The results are in contradiction to a d-wave symmetry of the order parameter, at least for the chain band.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007750426204
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...