scholarly journals Theoretical Derivation of Critical Current Density and Critical Magnetic Field Considering Many-Body Interactions of Magnetic Flux Quanta

2021 ◽  
Author(s):  
Shinichi Ishiguri
Keyword(s):  
Magnetic Field ◽  
Critical Temperature ◽  
Magnetic Flux ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Critical Magnetic Field ◽  
Many Body ◽  
Magnetic Flux Quantum ◽  
Many Body Interactions

To clarify the relationships among critical temperature, critical magnetic field, and critical current density, this paper describes many-body interactions of quantum magnetic fluxes (i.e., vortices) and calculates pinning-related critical current density. All calculations are analytically derived, without numerical or fitting methods. After calculating a magnetic flux quantum mass, we theoretically obtain the critical temperature in a many-body interaction scenario (which can be handled by our established method). We also derive the critical magnetic field and inherent critical current density at each critical temperature. Finally, we determine the pinning-related critical current density with self-fields. The relationships between the critical magnetic field and critical temperature, inherent critical current density and critical temperature, and pinning critical current density and self-magnetic field were consistent with experimental observations. From the critical current density and critical magnetic field, we clarified the magnetic field transition. It appears that a magnetic flux quantum collapses when the lattice of magnetic flux quanta melts. Our results, combined with our previously published papers, provide a comprehensive understanding of the transition points in high-Tc cuprates.

scholarly journals Температурные зависимости критических параметров неоднородных сверхпроводящих пленок

2021 ◽  
Vol 63 (8) ◽  
pp. 1035
Author(s):  
П.И. Безотосный ◽  
К.А. Дмитриева
Keyword(s):  
Magnetic Field ◽  
Critical Temperature ◽  
External Magnetic Field ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Superconducting Films ◽  
Critical Magnetic Field ◽  
Temperature Dependences ◽  
Comparison Of The Results

The results of calculating the temperature dependences of the critical current density and critical magnetic field of thin inhomogeneous superconducting films are presented. Comparison of the results obtained for inhomogeneous films with the results of calculations for homogeneous ones showed that in both cases, the decrease in the critical magnetic field occurs according to the root law, and the critical current density changes according to a power law with a degree of 3/2 when approaching the critical temperature. Quantitatively, the critical current density for inhomogeneous films in the absence of an external magnetic field is lower than for homogeneous ones. In turn, the critical magnetic field of inhomogeneous films is much larger than the critical field of homogeneous films.

Critical Current Density and Flux Pinning Properties in Superconducting MgB2 with and without SiC Doping

2013 ◽  
Vol 750 ◽  
pp. 293-297
Author(s):  
Wen Xu Sun ◽  
Bao Rong Ni ◽  
Akiyoshi Matsumoto ◽  
Hiroaki Kumakura
Keyword(s):  
Magnetic Field ◽  
Critical Current Density ◽  
Critical Current ◽  
High Magnetic Field ◽  
Current Density ◽  
Flux Pinning ◽  
Critical Magnetic Field ◽  
Pinning Mechanism ◽  
Pinning Potential ◽  
Force Displacement

It is well known that SiC doping in superconducting MgB2 improves the upper critical magnetic field (Bc2) and the critical current density (Jc) under high magnetic field. However, the relationship between SiC doping and the flux pinning mechanism has not been clarified. In this study, several MgB2 samples with and without SiC doping were prepared by the conventional in situ powder-in-tube method. The critical current densities and the force-displacement characteristics of fluxoids in samples were investigated by an ac inductive measurement (Campbell’s method). The Labusch parameter (αL) and the interaction distance (di) were estimated from the obtained force-displacement profile. It was found that SiC doping enhances the values of αL, but does not change the characteristics of the magnetic field dependence of αL apparently. Namely, αL vs. B3/2 characteristics in the pure samples and SiC doped samples are almost the same. Such a result of αL properties implies that the pinning mechanism in the SiC doped samples could be consistent with the conventional pinning theory. On the other hand, di, which is considered to be proportional to the size of pinning potential, decreases rapidly with increasing magnetic field, especially in the pure samples. For high magnetic field region, the variations of di were deduced to be caused by flux creep. The depth of pinning potential, U0, was estimated by using the values of αL and di. The values of U0 give evidence of that SiC doping can prevent the flux bundles moving to another pinning center under high magnetic field.

scholarly journals Surface Superconductivity of Vanadium

2021 ◽  
Vol 132 (3) ◽  
pp. 453-456
Author(s):  
I. N. Khlyustikov
Keyword(s):  
Critical Temperature ◽  
Magnetic Flux ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Persistent Currents ◽  
Surface Superconductivity

Abstract The critical temperature of the surface superconductivity in vanadium (Tcs) is found to be 0.04 K higher than the critical temperature of its volume superconductivity (Tcv). Surface superconductivity persistent currents can effectively trap a magnetic flux. The critical current density of the surface superconductivity is estimated at js = 5 × 106 A/cm2 at T = Tcv.

STUDY OF THE TEXTURING IN BSCCO-AG TAPES THROUGH MAGNETIC MEASUREMENTS

2000 ◽  
Vol 14 (25n27) ◽  
pp. 3159-3164
Author(s):  
C. FERDEGHINI ◽  
M. R. CIMBERLE ◽  
G. GRASSO ◽  
P. GUASCONI ◽  
A. MALAGOLI ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Magnetic Measurements ◽  
Texture Evolution ◽  
Rolling Direction ◽  
Longitudinal Direction ◽  
Magnetic Method ◽  
Superconducting Compounds

We have developed a method that allows, by a simple set of magnetic measurements, to study the texturing of the grains inside a BSCCO-Ag tape. Because the texture is anisotropic we define the angle ϑ L that identifies the mean grain misalignment angle with respect to the tape surface in longitudinal direction (i.e. rolling direction) and the angle ϑ T in transverse direction. The technique is based on the assumption that, because of the very high anisotropy of the critical current density in BSCCO superconducting compounds, the magnetic moment is essentially generated by the current circulating in the a-b planes of the BSCCO grains. The different magnetisation cycles, measured when the orientation of the magnetic field with respect to the tape surface is changed, depend only on the grain orientation inside the tape, which determines the effective magnetic field component normal to the a-b planes of the grains. Here we present the texture evolution of the BSCCO grains inside silver sheated multifilamentary tape starting from the initial steps of the mechanical deformation up to the final heating stage. The results obtained from the magnetic method are compared with those obtained with other methods, i.e. X-ray diffraction and critical current density anisotropy. Also results obtained on samples prepared in different way will be presented.

The Critical Current Density and the Curvature of the Magnetic Field in Epitaxial YBaCuO Films

1992 ◽  
Vol 170 (2) ◽  
pp. 549-562 ◽  
Author(s):  
D. Glatzer ◽  
A. Forkl ◽  
H. Theuss ◽  
H. U. Habermeier ◽  
H. Kronmüller
Keyword(s):  
Magnetic Field ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
The Magnetic Field

Effect of magnetic field on the resistive transition and critical current density of Y-Ba-Cu-O/Ag rolled tapes

1991 ◽  
Author(s):  
G. Swaminathan ◽  
S. Rajendra Kumar ◽  
N. Ramadas ◽  
K. Venugopal ◽  
K. A. Durga Prasad ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Resistive Transition

Magnetic-Field and Temperature Dependence of the Critical Current Density in High-Quality Bi2Sr2Ca2Cu3Ox Thin Films

1993 ◽  
pp. 493-496 ◽  
Author(s):  
Hirofumi Yamasaki ◽  
Kazuhiro Endo ◽  
Shin Kosaka ◽  
Masaichi Umeda ◽  
Shunji Misawa ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Thin Films ◽  
Critical Current Density ◽  
Temperature Dependence ◽  
Critical Current ◽  
Current Density ◽  
High Quality

Effect of Heat Treatment on Critical Current Density–Magnetic Field Curve for YBa2Cu3O7-δSingle Crystal and Its Microstructure

2000 ◽  
Vol 39 (Part 1, No. 10) ◽  
pp. 5822-5827 ◽  
Author(s):  
Akihiro Oka ◽  
Satoshi Koyama ◽  
Teruo Izumi ◽  
Yuh Shiohara ◽  
Junko Shibata ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Heat Treatment ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density

Estimation of Local Current Transport Properties in Thin Film Superconductor Based on Scanning Hall-probe Microscopy

2012 ◽  
Vol 1434 ◽  
Author(s):  
Kohei Higashikawa ◽  
Kei Shiohara ◽  
Masayoshi Inoue ◽  
Takanobu Kiss ◽  
Masateru Yoshizumi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Thin Film ◽  
Critical Current Density ◽  
Electric Field ◽  
Critical Current ◽  
Current Density ◽  
Limiting Factors ◽  
Hall Probe ◽  
Scanning Hall Probe Microscopy ◽  
Field Criterion

ABSTRACTTo enhance a global critical current in a superconductor, it is indispensable to understand current limiting factors and their influence on such a critical current. From this point of view, we have investigated in-plane distribution of local critical current density and its electric field criterion in a thin-film superconductor by using scanning-Hall probe microscopy. In a remanent state, after the application of sufficiently high magnetic field to a sample, current flows at critical current density according to the critical state model. Such distribution of current density was estimated from that of measured magnetic field using the Biot-Savart law. Furthermore, the corresponding electric field criterion was evaluated from the relaxation of such remanent magnetic field by considering Faraday’s law. This means that we could estimate in-plane distribution of local critical current density as a function of electric field criterion in a nondestructive manner. This characterization method would be very helpful for finding current limiting factors in a thin-film superconductor and their influence on its global current density versus electric field properties which would usually be obtained by four-probe method.

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