scholarly journals Magnetoresistance, critical current density, and magnetic flux pinning mechanism in nickel doped BaFe2As2 single crystals

2011 ◽  
Vol 109 (7) ◽  
pp. 07E151 ◽  
Author(s):  
M. Shahbazi ◽  
X. L. Wang ◽  
Z. W. Lin ◽  
J. G. Zhu ◽  
S. X. Dou ◽  
...  
Keyword(s):  
Magnetic Flux ◽  
Critical Current Density ◽  
Single Crystals ◽  
Critical Current ◽  
Current Density ◽  
Flux Pinning ◽  
Pinning Mechanism ◽  
Magnetic Flux Pinning

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.

Enhancement of superconducting critical current density by Fe impurity substitution in NbSe2 single crystals and the vortex pinning mechanism

2017 ◽  
Vol 19 (18) ◽  
pp. 11230-11238 ◽  
Author(s):  
Rukshana Pervin ◽  
Manikanadan Krishnan ◽  
Amit Kumar Rana ◽  
M. Kannan ◽  
S. Arumugam ◽  
...  
Keyword(s):  
Critical Current Density ◽  
Temperature Dependence ◽  
Single Crystals ◽  
Critical Current ◽  
Current Density ◽  
Vortex Pinning ◽  
Pinning Mechanism ◽  
Fe Impurity

This study demonstrates the temperature dependence of Hsb and Hlb for (a) NbSe2, (b) Fe0.0008NbSe2 and (c) Fe0.0011NbSe2 fitted with the δl and δTc pinning mechanism, respectively.

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.

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.

Sign in / Sign up

Export Citation Format

Share Document