scholarly journals Study of flux pinning mechanism under hydrostatic pressure in optimally doped (Ba,K)Fe2As2 single crystals

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Babar Shabbir ◽  
Xiaolin Wang ◽  
Y. Ma ◽  
S. X. Dou ◽  
S. S. Yan ◽  
...  
Author(s):  
Yongqiang Pan ◽  
Nan Zhou ◽  
Bencheng Lin ◽  
Jinhua Wang ◽  
Zengwei Zhu ◽  
...  

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.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
S. Arumugam ◽  
Manikandan Krishnan ◽  
Kent Ishigaki ◽  
Jun Gouchi ◽  
Rukshana Pervin ◽  
...  

Author(s):  
Y. Feng ◽  
X. Y. Cai ◽  
R. J. Kelley ◽  
D. C. Larbalestier

The issue of strong flux pinning is crucial to the further development of high critical current density Bi-Sr-Ca-Cu-O (BSCCO) superconductors in conductor-like applications, yet the pinning mechanisms are still much debated. Anomalous peaks in the M-H (magnetization vs. magnetic field) loops are commonly observed in Bi2Sr2CaCu2Oy (Bi-2212) single crystals. Oxygen vacancies may be effective flux pinning centers in BSCCO, as has been found in YBCO. However, it has also been proposed that basal-plane dislocation networks also act as effective pinning centers. Yang et al. proposed that the characteristic scale of the basal-plane dislocation networksmay strongly depend on oxygen content and the anomalous peak in the M-H loop at ˜20-30K may be due tothe flux pinning of decoupled two-dimensional pancake vortices by the dislocation networks. In light of this, we have performed an insitu observation on the dislocation networks precisely at the same region before and after annealing in air, vacuumand oxygen, in order to verify whether the dislocation networks change with varying oxygen content Inall cases, we have not found any noticeable changes in dislocation structure, regardless of the drastic changes in Tc and the anomalous magnetization. Therefore, it does not appear that the anomalous peak in the M-H loops is controlled by the basal-plane dislocation networks.


1995 ◽  
Vol 05 (C8) ◽  
pp. C8-729-C8-734
Author(s):  
A.I. Lotkov ◽  
V.P. Lapshin ◽  
V.A. Goncharova ◽  
H.V Chernysheva ◽  
V.N. Grishkov ◽  
...  

1997 ◽  
Vol 282-287 ◽  
pp. 2125-2126 ◽  
Author(s):  
X.L. Wang ◽  
J. Horvat ◽  
H.K. Liu ◽  
S.X. Dou
Keyword(s):  

1999 ◽  
Vol 328 (1-2) ◽  
pp. 1-13 ◽  
Author(s):  
S.I Schlachter ◽  
W.H Fietz ◽  
K Grube ◽  
Th Wolf ◽  
B Obst ◽  
...  

1991 ◽  
Vol 58 (14) ◽  
pp. 1566-1568 ◽  
Author(s):  
L. J. Swartzendruber ◽  
D. L. Kaiser ◽  
F. W. Gayle ◽  
L. H. Bennett ◽  
A. Roytburd

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