Dependence Of Penetration Depth Research Articles

Upper critical field, penetration depth, and GL parameter of Tl-2223 single crystals

A Tl 2Ca 2Ba 2Cu 3O 10 single crystal of platelet shape with T c=121.5 K was investigated by SQUID magnetometry. Zero field cooled (=ZFC) and field cooled (=FC) measurements were carried out in different fields with the applied field parallel to the crystallographic c-axis. Taking the fluctuations of the vortices in Josephson-coupled layered superconductors into account, the temperature dependent penetration depth λ ab, the Ginzburg Landau parameter κ, and the upper critical field H c2 are calculated from the reversible ZFC/FC magnetization data. The H c2-data (Hc) can be fitted linearly at higher temperatures. The temperature dependent penetration depth does not follow the empirical law λ( T)=λ(0)/(1−( T/T c ) 4) 1 2 .

Penetration depth measurements for Nd 1.85Ce 0.15CuO 4 and NbCN thin films using a kinetic inductance technique

The absolute value and the temperature dependence of the magnetic penetration depth λ( T) have been measured for high-quality NbCN and Nd 1.85Ce 0.15CuO 4 (NCCO) thin films. A kinetic inductance technique was used to measure the screening of a thin superconducting film where the film thickness d was less than or of the order of the London penetration depth. In this limit the kinetic inductance L k is proportional to λ 2( T)/ d. The kinetic inductance was measured on unpatterned films using a two-coil mutual inductance technique. It was found that the temperature dependence of the penetration depth for NbCN and NCCO at low temperatures is exponential as expected, confirming earlier reports. We also describe how λ(0) can be extracted from the kinetic inductance data.

The frequency and DC magnetic field dependence of the RF penetration depth in the solid and fluid vortex phases of Bi-Pb-Sr-Ca-Cu-O

The frequency and DC magnetic field dependence of the change in the RF penetration depth resulting from vortex-induced dissipation has been measured in Bi-Pb-Sr-Ca-Cu-O above and below the depinning transition. The dissipation is shown to have a linear dependence on B1/2 at constant temperature in the solid and fluid vortex phases with a different slope in each phase. The dissipation is observed to be independent of frequency in the pinned regime but decreases with increasing frequency in the fluid state. The magnetic field at which the transition occurs at constant temperature is frequency dependent, decreasing with increasing frequency. The results are in general agreement with theoretical predictions of the magnetic field and frequency dependence of the penetration depth.

The temperature dependence of resonant frequency shift in microwave cavity for high T c superconductors

The dispersive detection of an electron-spin resonance spectrometer is far more sensitive than the conventional absorptive detection. It has been successfully exploited to verify the superconducting state for the recently developed high T c superconductors by the observation of resonant frequency shift in a TE 102 microwave cavity. We attribute the increase of resonant frequency as temperature decreases to be due to the Meissner effect for T < T c and the skin-depth effect for T > T c . The temperature dependence of penetration depth λ( T) following the Casimir-Gorter relation is not adequate to account for the frequency drift at T below T c , while it can be elucidated more fully by the heavy-Fermion pairing mechanism.

TICaBaCuO high Tc superconducting microstrip ring resonators designed for 12 GHz

Microwave properties of sputtered TICaBaCuO thin films were investigated by designing, fabricating and testing microstrip ring resonators. Ring resonators designed for 12 GHz fundamental resonance frequency, were fabricated and tested. From the unloaded Q values for the resonators, the surface resistance was calculated by separating the conductor losses from the total losses. The penetration depth was obtained from the temperature dependence of resonance frequency, assuming that the shift in resonance frequency is mainly due to the temperature dependence of penetration depth. The effective surface resistance at 12 GHz and 77 K was determined to be between 1.5 and 2.75 mΩ, almost an order lower than Cu at the same temperature and frequency. The effective penetration depth at 0 °K is approximately 7000 Å.

Temperature dependent magnetic penetration depth of Co and Zn doped YBa 2Cu 3O 7 obtained from the AC susceptibility of magnetically aligned powders

We have measured the absolute value and temperature dependence of the magnetic penetration depth λ( T) of magnetically aligned cobalt and zinc doped YBa 2Cu 3O 7-δ (YBCO) using a commercial AC susceptometer. For pure YBCO, our values of λ ab (0)≅140 nm and λ c (0)≅1040 nm agree with other published values. We find increasing the Co doping increase both the fluctuation effects and the anisotropy ratio λ c /λ ab , probably due to the reduction of coupling in the c-direction, while doping with Zn substantially increases both λ ab and λ c . Our data imply a large, highly anisotropic gap whose maximum value is 2 Δ(0)≅10 k B T c. All samples show a T 2 term in both λ ab ( T) and λ c ( T) at low temperatures ( T<0.6 T c), in apparent disagreement with conventional s-wave BCS pairing. The possible explanations of this result are discussed.

Anisotropic superconducting gap of Bi2Sr2CaCu2O8 : tunneling spectroscopy with STM

The tunneling conductance was measured in the superconducting phase of Bi 2 Sr 2 CaCu 2 O 8 with use of the STM and the temperature dependence of magnetic field penetration depth was also investigated by the magnetization measurement. The obtained differential conductance is reduced to almost zero and flat near zero bias voltage indicating the finite gap on the whole Fermi surface, while a considerable gap anisotropy is found. The total conductance curve was explained by the anisotropic gap ranging from 10 meV to 30 meV. The temperature dependence of penetration depth is of the thermal activation type with the activation energy of 14 meV. These results indicate that the superconductivity in cuprate high T C superconductor is given by the attractive interaction between electrons of the predominant s-wave symmetry mixed with the d-wave

Arrays of fluxoids in the high-TC superconductors and their putative phase transitions (invited)

The static and dynamic properties of the magnetic vortices which penetrate films and crystals of the high-TC superconductors in fields above Hc1 have been examined in a variety of experiments. Direct visualization at low fields has been augmented with frequency dependent ac susceptibility, penetration depth, magnetization relaxation (using high-Q mechanical oscillators), and resistance measurements at high fields in an effort to obtain a complete understanding of the vortex dynamics. The various models for the vortex phase diagram, including isolated and collective vortex pinning, vortex lattice melting, and thermodynamic glass transitions are compared to the data. The bulk of the data presently available are consistent with strong pinning of independent vortices. Deviations from this model suggest where more complicated dynamics may become important.

Magnetic Penetration Depth Measurements and Inhomogeneity in YBa2Cu3O7−δ Superconducting Thin Films

ABSTRACTThe microstrip resonator technique has been applied to study the temperature dependence of the magnetic penetration depth in high quality YBa2Cu3O7−δ thin films. The temperature dependence at low temperatures comes out directly from measured data, with no assumptions about transmission line geometry, dielectric properties, or a model for the temperature dependence of the penetration depth. One can interpret the data in terms of either an exponential decay of λ(T) at low temperatures or as a power law decay. The energy gaps obtained from the exponential decay at low temperature are found to be significantly smaller than weak coupled BCS theory and power-law exponents are in the range of 1.3 to 3.2. These results will be discussed in terms of microscopic theories and the possibility that materials properties dominate the measurement.

Temperature dependence of penetration depth in thin film niobium

A novel technique is presented which should allow precise determination of the temperature dependence of the inductance, and hence of the penetration depth, of superconducting niobium thin-film structures. Four niobium thin-film stripline inductors are arranged in a bridge configuration, and inductance differences are measured using a potentiometric technique with a SQUID (superconducting quantum interference device) as the null detector. Numerical simulations of the stripline inductances are presented which allow the performance of the measurement technique to be evaluated. The prediction of the two-fluid model for the penetration-depth temperature dependence is given for reduced temperatures of 0.3 to 0.9. The experimental apparatus and its resolution and accuracy are discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Study on penetration depth and its dependence on frequency, soil moisture, texture and temperature in the context of microwave remote sensing

A theoretical study has been made to see the influence of microwave frequency, soil moisture, soil texture and soil temperature on penetration depth in the context of microwave remote sensing. The results are presented in the form of figures and also coefficients of least square fitting. The study reveals that there is a definite dependence of penetration depth on the above parameters. The range of penetration depth has been found to be 0 to 10 cms and varies as a function of several parameters. These results are in agreement with experimental observations.

印刷インキの転移と紙への浸透

Ink transfer and penetration are of great importance in printing processes. These phenomena were reviewed from a viewpoint of an interaction between the printing ink and the paper stock having a porous structure.An ink transfer equation can be represented using an amount of fixed ink on paper surface and a coefficient of ink splitting. The amount of fixed ink depends on printing speed, printing pressure, ink viscosity, and the porosity of paper. The coefficient of ink splitting is also affected by the porosity of paper extremely.The initial setting of printing ink is greatly influenced by the speed of ink penetration which depends on the porosity of the paper. A large part of total pore volume of paper is attributable to an amount of interfibrillar gap. Ink penetration can be monitored by the reflection density of the reverse side of the printed paper using a photoelectric reflectometer as employed by Voet and Brand.The phenomenon of ink penetration can be predicted by Lucas-Washburn's equation or Olsson-Pihl's equation the penetration depth increases in proportion to square root of time and mean radius of pore.For a coated paper, the pore structure in the coating layer is different from that in the body stock and the pore size of the former is extremely small. The pore structure in the coating layer behaves as a filter, only ink vehicle penetrates into the coated stock and the penetration speed is not so fast.The measurement of the time dependence of the penetration depth is an effective method to investigate the capillary structure in paper stocks. We can also evaluate the ink-setting characteristics from the dependence of penetration depth on time.

Superconducting penetration depth in amorphous metals

We show that temperature dependent penetration depth measurements can be used to characterize the superconductive behaviour of amorphous metals.

A SIMPLE QUALITATIVE DETERMINATION OF JOSEPHSON TUNNEL JUNCTION PARAMETERS NEAR THE TRANSITION TEMPERATURE

A SIMPLE QUALITATIVE DETERMINATION OF JOSEPHSON TUNNEL JUNCTION PARAMETERS NEAR THE TRANSITION TEMPERATURE

The theory of the effect of anisotropic scattering by impurities on the electromagnetic response of superconductors

The usual theory of scattering by non-magnetic impurities in superconductors is extended to cases where the scattering is not isotropic and the mean free path, l, is not very short. The starting point is the equation for the vertex function from which the electromagnetic response of the superconductor is derived. The anomalous limit, ql>>1 where q is a typical wavevector of the field, is studied in some detail and, in particular, the dependence of penetration depth on mean free path is derived. The results show that anisotropic scattering gives rise to measurable deviations from the theory of Mattis and Bardeen (1958).

Exit angle dependence of penetration depth of backscattered electrons in the scanning electron microscope

The variation of penetration depth of backscattered electrons with exit angle is investigated by Monte Carlo calculations. It is confirmed that the mean penetration depth of backscattered electrons increases linearly with exit angle. To see qualitatively the extent of penetration of backscattered electrons, trajectories are plotted by selecting the exit angle. Some studies of the Everhart model for electron backscattering are done to calculate the mean penetration depth. The modified model provides a relatively good prediction in comparison with Monte Carlo calculations. Mit Monte-Carlo-Rechnungen wird die Änderung der Eindringtiefe von Rückstreu-elektronen mit dem Austrittswinkel untersucht. Es wird bestätigt, daß die mittlere Eindringtiefe der Rückstreuelektronen linear mit dem Austrittswinkel zunimmt. Um qualitativ das Ausmaß des Eindringens der rückgestreuten Elektronen abzuschätzen, werden Trajektorien durch Wahl der Austrittswinkel aufgezeichnet. Einige Untersuchungen des Everhart-Modells für Rückstreuelektronen werden durchgeführt, um die mittlere Eindringtiefe zu berechnen. Das modifizierte Modell liefert eine relativ gute Vorhersage im Vergleich zu Monte-Carlo-Rechnungen.

Temperature Dependence of Penetration Depth of a Magnetic Field in Superconductors

Temperature Dependence of Penetration Depth of a Magnetic Field in Superconductors