CO-Sputtered Composite films Of YBa2Cu3O7−xand LaAIO3

1992 ◽  
Vol 275 ◽  
Author(s):  
L. H. Allen ◽  
E. J. Cukauskas ◽  
G. K. Sherrill ◽  
R. T. Holm
Keyword(s):  
Magnetic Field ◽  
Critical Current ◽  
Landau Theory ◽  
Composite Films ◽  
Zero Field ◽  
Pinning Force ◽  
Perpendicular Magnetic Field ◽  
Ginzburg Landau ◽  
Thin Film Composites ◽  
Film Composites

ABSTRACTWe have grown thin film composites of and YBa2Cu3O7−x and LaAlO3 by co-sputtering. A film with composition of 10% LaAIO3 by volume had a transition temperature of 58K and critical current density of 1.2 × 106 A/cm2 at 4K. We measured the temperature dependence of the critical current and obtained a good fit with Ginzburg-Landau theory for thin films. A perpendicular magnetic field was applied, and the critical current and pinning force measured. At 70 kOe, the critical current was suppressed only a factor of 4 from its zero-field value. The measured pinning force was 2 × 109 dyn/cm3 at 70 kOe and is comparable to that of YBa2Cu3O7−x films.

MAGNETIZATION STUDIES OF Rb3C60 IN SUPERCONDUCTING STATE

1993 ◽  
Vol 07 (11) ◽  
pp. 2163-2176 ◽  
Author(s):  
C. POLITIS ◽  
V. BUNTAR ◽  
V.P. SEMINOZHENKO
Keyword(s):  
Magnetic Field ◽  
Temperature Dependence ◽  
Critical Current ◽  
Magnetic Measurements ◽  
Landau Theory ◽  
Critical Magnetic Field ◽  
Zero Temperature ◽  
Ginzburg Landau ◽  
Different Temperatures ◽  
Increasing Temperature

We present the results of magnetic measurements in fields up to 50 kOe for superconducting Rb 3 C 60. The temperature dependence of upper H c 2 critical magnetic field is determined, from which the zero temperature value Hc2(0)=465±50 kOe is evaluated. The magnitudes of penetration depth and coherence length are calculated as ξ(0)=26.7±3 Å; λ L (0)=2150±100 Å at zero temperature. The temperature dependence of ξ(T) and λ L (T) for T≧23 K is in good agreement with the Ginzburg-Landau theory. The critical current densities for different temperatures are calculated, showing a strong decrease of Jc with increasing temperature for T≤7 K . Two regions of fading critical current density on a magnetic field dependence are found.

SUPERCONDUCTING STATE OF A PERFORATED MESOSCOPIC DISK WITH A SQUARE OR TRIANGULAR TRENCH

2013 ◽  
Vol 27 (15) ◽  
pp. 1350115 ◽  
Author(s):  
J. BARBA-ORTEGA ◽  
J. BARÓN JAIMEZ ◽  
J. ALBINO AGUIAR
Keyword(s):  
Magnetic Field ◽  
Landau Theory ◽  
Outer Boundary ◽  
Pinning Force ◽  
Restricted Range ◽  
Superconducting Properties ◽  
Competing Interactions ◽  
Ginzburg Landau ◽  
New Phenomena ◽  
The Magnetic Field

In this paper, we report on the influence of a square (triangular) trench on the superconducting properties of a perforated mesoscopic sample. Effects associated to the pinning force of the hole versus the pinning by the trench and interplay between the shape of the outer boundary and the shape of the inner defects on the vortex configuration are studied for a thin disk. Using the Ginzburg–Landau theory, we calculate the magnetization, vorticity, free energy, magnetic induction, supercurrent and superconducting order parameter as a function of the applied perpendicular magnetic field. We show that only in a restricted range of the magnetic field the vortex configuration obeys the geometry of the trench. Nevertheless, we clearly demonstrate that in our sample new phenomena are possible due to competing interactions of the geometry of the sample and the added geometry of the nanoengineered trench.

scholarly journals Моделирование критического состояния слоистых сверхпроводящих структур с неоднородными слоями

2021 ◽  
Vol 63 (10) ◽  
pp. 1471
Author(s):  
П.И. Безотосный ◽  
К.А. Дмитриева
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Critical Current ◽  
Layered Structures ◽  
Pinning Force ◽  
Ginzburg Landau ◽  
Number Of Layers ◽  
Ginzburg Landau Equations ◽  
The One ◽  
The Magnetic Field

An approach for calculating the critical state of layered structures consisting of inhomogeneous superconducting layers is proposed. The method is based on the numerical solution of the one-dimensional Ginzburg-Landau equations, generalized for an inhomogeneous plate. The method allows one to obtain the dependence of the critical current on the magnetic field, as well as the distribution of the current and magnetic field over the layers. A comparison is made of the averaged critical current of layered structures consisting of both inhomogeneous and homogeneous layers. It was found that with a relatively small number of layers and a small external magnetic field, the critical current of layered structures with homogeneous layers can exceed the critical current of structures with inhomogeneous layers. With an increase in the number of layers and / or the value of the external magnetic field, the critical current of layered structures with inhomogeneous layers begins, on the contrary, to exceed the critical current of structures with homogeneous layers. The pinning force in structures with inhomogeneous layers is higher than in the case of homogeneous ones.

TEMPERATURE DEPENDENCE OF THE CRITICAL CURRENT DENSITY OF SUPERCONDUCTORS IN TWO-BAND GINZBURG–LANDAU THEORY: APPLICATION TO MgB2

2004 ◽  
Vol 18 (13) ◽  
pp. 1931-1936 ◽  
Author(s):  
I. N. ASKERZADE
Keyword(s):  
Critical Current Density ◽  
Temperature Dependence ◽  
Critical Current ◽  
Current Density ◽  
Magnesium Diboride ◽  
Landau Theory ◽  
Ginzburg Landau ◽  
Theory Application ◽  
Gl Theory ◽  
Good Agreement

Temperature dependence of the critical current density j c (T) for the superconducting magnesium diboride MgB 2 is studied in the vicinity of T c by using a two-band Ginzburg–Landau (G–L) theory. The result is in good agreement with experimental data for a bulk MgB 2. Comparision of obtained results with single-band GL theory are presented.

Ginzburg–Landau Theory for Two-Band Isotropic s-Wave Superconductors

2003 ◽  
Vol 17 (16) ◽  
pp. 3001-3020 ◽  
Author(s):  
I. N. Askerzade
Keyword(s):  
Magnetic Field ◽  
Critical Field ◽  
Landau Theory ◽  
Upper Critical Field ◽  
Single Band ◽  
S Wave ◽  
Ginzburg Landau ◽  
Surface Magnetic Field ◽  
Specific Heat Jump ◽  
Gl Theory

Temperature dependence of the upper critical field Hc2(T), lower critical field Hc1(T) and thermodynamic magnetic field Hcm(T) are studied in the vicinity of Tc using a two-band Ginzburg–Landau (GL) theory. The results are shown to be in a good agreement with experimental data for the superconducting magnesium diboride (MgB2) and non-magnetic borocarbides LuNi 2 B 2 C ( YNi 2 B 2 C ). In addition, two-band GL theory was applied for the calculation of specific heat jump, which is smaller than in single-band GL theory. Peculiarities of Little–Parks effect in two-band GL theory are studied also. It is shown that the quantization of the magnetic flux and the relation between surface magnetic field Hc3(T) and upper critical field Hc2(T) are the same as in single band GL theory.

Dynamics of vortex–antivortex creation and annihilation in current-driven mesoscopic superconducting squares

2015 ◽  
Vol 29 (35n36) ◽  
pp. 1550247
Author(s):  
Xiao-Meng Liang ◽  
Guo-Qiao Zha
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Landau Theory ◽  
Symmetric Case ◽  
Time Dependent ◽  
Dynamical Process ◽  
Applied Bias ◽  
Ginzburg Landau ◽  
Dc Drive ◽  
Vortex Velocity

In this paper, based on the time-dependent Ginzburg–Landau theory, we study the dynamics of vortex–antivortex (V–Av) pairs in a mesoscopic superconducting square with a small hole under applied bias currents. For the sample with a centered hole, a V–Av pair can nucleate at the hole edges and moves in opposite directions perpendicular to applied constant DC drive. The influence of the external magnetic field on the (anti)vortex velocity and the lifetime of V–Av pairs is mainly investigated. Different modes in the dynamical process of the V–Av collision and annihilation are identified. Moreover, in the case when the hole is displaced from the center of the square, the V–Av dynamics behaves quite differently from the symmetric case due to the shift of the V–Av creation point.

Effect of Pulsed Magnetic Field Processing on MgB2 Superconductors

2007 ◽  
Vol 546-549 ◽  
pp. 2063-2066 ◽  
Author(s):  
W.X. Li ◽  
Ying Li ◽  
M.Y. Zhu ◽  
R.H. Chen ◽  
H.M. Jin ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Pulsed Magnetic Field ◽  
Pinning Force ◽  
Critical Current Density Jc ◽  
Mgb2 Superconductors ◽  
Doped Mgb2 ◽  
Flux Pinning Force

Pulsed magnetic field was first employed in the study on MgB2 superconductors. Superconductivity properties and microstructures of Zn and SiC doped MgB2 were discussed in this paper. The superconductors showed different superconductivities after magnetic sintering. Critical current density and flux pinning force were relevant to the dopants properties in MgB2. Grains in the pulsed magnetic processed MgB2 matrix were smaller than those in the normal processed one. The refinement microstructures have caused the critical current density (Jc) anisotropy in both the Zn and SiC doped MgB2.

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