Critical Current Densities in Bi2Sr2Cacu2O8+D

1989 ◽  
Vol 169 ◽  
Author(s):  
Shunji Nomura ◽  
Yutaka Yamada ◽  
Tomohisa Yamashita ◽  
Eriko Yoneda ◽  
Hisashi Yoshino ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Flux Pinning ◽  
Pinning Force ◽  
Critical Fields ◽  
Current Densities ◽  
Upper Critical Fields ◽  
The Magnetic Field

AbstractCritical current densities and upper critical fields were measured for a single crystal of the high Tc oxide superconductor, Bi2Sr2CaCu2O8+d, within the ab basal plane and along the c axis. The anisotropy in critical current densities was observed to be Jc⊥/Jc//=10 in agreement with the anisotropy in resistivity for the normal state. The magnetic field dependence of the critical current densities can be interpreted by the anisotropy in the upper critical fields. The scaling of the critical current density with the magnetic field was found. The critical current density scaled to zero at fields Bc2 in the ab plane and along the c axis which were in good agreement with the upper critical fields measured by transport.The anisotropy in flux pinning force density along the b axis, Fp//b, and along the a axis, Fp//a, was found to be Fp//b/Fp//a=3. The data provided strong evidence for flux pinning by the modulated structure in this system.

Critical Current Characteristics and Flux Pinning in Fe-Based Pnictide Superconductor

2013 ◽  
Vol 750 ◽  
pp. 288-292
Author(s):  
Bao Rong Ni ◽  
Edmund S. Otabe ◽  
Masaru Kiuchi ◽  
Yan Wei Ma
Keyword(s):  
Magnetic Field ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Flux Pinning ◽  
Ac Susceptibility ◽  
Pinning Mechanism ◽  
Temperature Dependences ◽  
Current Densities ◽  
Current Characteristics

The superconducting Ba1-xKxFe2As2(x = 0.4) single crystals were prepared by the so-called FeAs self-flux method. The critical temperature by ac susceptibility measurement was estimated to be about 36 K. The magnetic field and temperature dependences of critical current densities were investigated by an ac inductive measurement (Campbell’s method). Unlike the phenomenon of co-existence of the global and local critical current densities observed in many polycrystalline Fe-based superconducting pnictides, it was found that only a uniform critical current density (Jc) flows through the whole sample. The value of Jcat 20 K and 1 T was about 5×108A/m2, which is much smaller than the local critical current density observed in polycrystalline samples. This result implies that a dissimilarity of flux pinning mechanism exists between these two kinds of materials. The force-displacement characteristic of fluxoids in sample was investigated. The Labusch parameter was found to increase monotonously with increasing magnetic field, while the interaction distance was proportional to the fluxoid spacing. These results are consistent with the prediction based on a simple flux pinning mechanism.

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

Anisotropic critical current density and flux pinning mechanism of Fe1+yTe0.6Se0.4 single crystals

2021 ◽  
Author(s):  
Yongqiang Pan ◽  
Nan Zhou ◽  
Bencheng Lin ◽  
Jinhua Wang ◽  
Zengwei Zhu ◽  
...  
Keyword(s):  
Critical Current Density ◽  
Single Crystals ◽  
Critical Current ◽  
Current Density ◽  
Flux Pinning ◽  
Magnetic Hysteresis ◽  
Magnetic Hysteresis Loop ◽  
Pinning Force ◽  
Magnetization Relaxation ◽  
Pinning Mechanism

Abstract Fe1+yTe0.6Se0.4 has considerable application potential due to its large critical current density (J c) and high upper critical magnetic field (H c2). However, the uncertainty of the anisotropy of J c and the unclear flux-pinning mechanism have limited the application of this material. In this study, the J c in three directions were obtained from magnetic hysteresis loop measurements. A large anisotropy of J c ab /J c c ~ 10 was observed, and the origin of the anisotropy was discussed in details. Flux pinning force densities (F p) were obtained from J c, and a non-scaling behavior was found in the normalized pinning force f p[F p/F p-max] versus the normalized field h[H/H c2]. The peaks of pinning force shift from a high h to a low h with increasing temperature. Based on the vortex dynamics analysis, the peak shift was found to originate from the magnetization relaxation. The J c and F p at critical states free from the magnetic relaxation were regained. According to the Dew-Hughes model, the dominant pinning type in Fe1+yTe0.6Se0.4 clean single crystals was confirmed to be normal point pinning.

scholarly journals Increased flux pinning force and critical current density in MgB2 by nano-La2O3 doping

2020 ◽  
Vol 756 ◽  
pp. 012019
Author(s):  
Danlu Zhang ◽  
Fang Wan ◽  
Michael D. Sumption ◽  
Edward W. Collings ◽  
CJ Thong ◽  
...  
Keyword(s):  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Flux Pinning ◽  
Pinning Force ◽  
Flux Pinning Force

PINNING FORCE DENSITY IN YBa2Cu3O7-FILMS AND YBa2Cu3O7/PrBa2Cu3O7-SUPERLATTICES

1993 ◽  
Vol 07 (01n03) ◽  
pp. 135-138
Author(s):  
M. SCHMITT ◽  
T. KLUGE ◽  
C. TOMÉ ROSA ◽  
G. JAKOB ◽  
P. WAGNER ◽  
...  
Keyword(s):  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Low Temperatures ◽  
Force Density ◽  
Pinning Force ◽  
Axis Of Rotation ◽  
Current Flows ◽  
The Magnetic Field ◽  
Pinning Force Density

The in plane critical current density jc (B, Θ, T) of dc-sputtered YBa 2 Cu 3 O 7-films and YBa 2 Cu 3 O 7/ PrBa 2 Cu 3 O 7-superlattices was measured in dependence of the angle Θ between the magnetic field [Formula: see text] and the [Formula: see text]-axis of the films in two orientations: 1. The current direction is parallel to the axis of rotation (i.e. [Formula: see text] always). 2. The current flows perpendicular to the axis of rotation (i. e. [Formula: see text]). For low temperatures we do not find any difference between the two current orientations, and the critical current density [Formula: see text] behaves like jc (B cos Θ, 0°). For higher temperatures the two cases differ from each other for Θ near to the maxima in jc at 90° and 270° for the YBa 2 Cu 3 O 7-films whereas for YBa 2 Cu 3 O 7/ PrBa 2 Cu 3 O 7-superlattices we hardly find any change for both experimental setups. We compare the behaviour of the experimental results for the two orientations for the YBa 2 Cu 3 O 7-films and YBa 2 Cu 3 O 7/ PrBa 2 Cu 3 O 7-superlattices and discuss the temperature dependence of the intrinsic pinning force density.

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