scholarly journals Giant increase of critical current density and vortex pinning in Mn doped KxFe2−ySe2 single crystals

2014 ◽  
Vol 105 (19) ◽  
pp. 192602 ◽  
Author(s):  
Mingtao Li ◽  
La Chen ◽  
Wen-Long You ◽  
Junyi Ge ◽  
Jincang Zhang
Keyword(s):  
Critical Current Density ◽  
Single Crystals ◽  
Critical Current ◽  
Current Density ◽  
Vortex Pinning ◽  
Mn Doped

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.

scholarly journals Critical Current Density and Vortex Dynamics in Pristine and Irradiated KCa2Fe4As4F2

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5283
Author(s):  
Sunseng Pyon ◽  
Soichi Taya ◽  
Yuto Kobayashi ◽  
Ayumu Takahashi ◽  
Wenjie Li ◽  
...  
Keyword(s):  
Critical Current Density ◽  
Single Crystals ◽  
Critical Current ◽  
Current Density ◽  
Vortex Dynamics ◽  
Dose Dependence ◽  
Vortex Pinning ◽  
Particle Irradiation ◽  
Before And After ◽  
Large Anisotropy

We report the critical current density (Jc) and vortex pinning properties in single crystals of a novel iron-based superconductor (IBS) KCa2Fe4As4F2 with large Jc in the pristine state, before and after introduction of artificial defects by swift-particle irradiation. The effects of 2.6 GeV U and 3 MeV proton irradiations in KCa2Fe4As4F2 single crystals on transition temperature Tc and Jc, including its dose dependence, are systematically studied. Jc~8 MA/cm2 under a self-field at 2 K in the pristine crystal is strongly enhanced up to 19.4 and 17.5 MA/cm2 by irradiation of 2.6 GeV U-ions and 3 MeV protons, respectively. Suppression of Tc and dose dependence of Jc in KCa2Fe4As4F2 is different from that in a representative IBS of (Ba,K)Fe2As2, which can be explained by considering the presence of embedded defects in pristine KCa2Fe4As4F2. The vortex dynamics in the pristine and proton irradiated KCa2Fe4As4F2 single crystals are also investigated from the analyses of the field dependence of Jc and the normalized magnetic relaxation rate. In addition to the contribution of embedded defects, weak collective pinning is considered for comprehensive analyses. Vortex dynamics in KCa2Fe4As4F2 is similar to those in (Ba,K)Fe2As2 to some extent, and different from that in anisotropic Li0.8Fe0.2OHFeSe. Large anisotropy, due to the presence of insulating blocking layers in KCa2Fe4As4F2, which leads to much lower irreversibility field (Hirr) compared with 122-type IBSs, strongly affect the vortex dynamics.

scholarly journals Influence of the carbon substitution on the critical current density and AC losses in MgB2 single crystals

2010 ◽  
Vol 78 (3) ◽  
pp. 359-365 ◽  
Author(s):  
M. Ciszek ◽  
K. Rogacki ◽  
K. Oganisian ◽  
N. D. Zhigadlo ◽  
J. Karpinski
Keyword(s):  
Critical Current Density ◽  
Single Crystals ◽  
Critical Current ◽  
Current Density ◽  
Ac Losses ◽  
Carbon Substitution

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 Enhancement of critical current density in a superconducting NbSe2 step junction

Nanoscale ◽  
2020 ◽  
Vol 12 (22) ◽  
pp. 12076-12082
Author(s):  
Xin He ◽  
Yan Wen ◽  
Chenhui Zhang ◽  
Zhiping Lai ◽  
Eugene M. Chudnovsky ◽  
...  
Keyword(s):  
Critical Current Density ◽  
Transport Properties ◽  
Critical Current ◽  
Current Density ◽  
Vortex Pinning ◽  
Step Junction

We investigate the transport properties of a NbSe2 step junction and verify that the enhancement of the critical current density is due to the vortex pinning at the step junction.

Crystal Growth of High Temperature Superconductors

MRS Bulletin ◽  
1988 ◽  
Vol 13 (10) ◽  
pp. 56-61 ◽  
Author(s):  
H.J. Scheel ◽  
F. Licci
Keyword(s):  
High Temperature ◽  
Critical Current Density ◽  
Single Crystals ◽  
Critical Current ◽  
Current Density ◽  
Large Scale ◽  
High Temperature Superconductivity ◽  
High Temperature Superconductors ◽  
Superconducting Transition ◽  
Theoretical Understanding

The discovery of high temperature superconductivity (HTSC) in oxide compounds has confronted materials scientists with many challenging problems. These include the preparation of ceramic samples with critical current density of about 106 A/cm2 at 77 K and sufficient mechanical strength for large-scale electrotechnical and magnetic applications and the preparation of epitaxial thin films of high structural perfection for electronic devices.The main interest in the growth of single crystals is for the study of physical phenomena, which will help achieve a theoretical understanding of HTSC. Theorists still do not agree on the fundamental mechanisms of HTSC, and there is a need for good data on relatively defect-free materials in order to test the many models. In addition, the study of the role of defects like twins, grain boundaries, and dislocations in single crystals is important for understanding such parameters as the critical current density. The study of HTSC with single crystals is also expected to be helpful for finding optimum materials for the various applications and hopefully achieving higher values of the superconducting transition temperature Tc than the current maximum of about 125 K. It seems unlikely at present that single crystals will be used in commercial devices, but this possibility cannot be ruled out as crystal size and quality improve.

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