scholarly journals Microstructure and Flux Pinning of Reacted-and-Pressed, Polycrystalline Ba0.6K0.4Fe2As2 Powders

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2173
Author(s):  
Michael R. Koblischka ◽  
Anjela Koblischka-Veneva ◽  
Jörg Schmauch ◽  
Masato Murakami
Keyword(s):  
Flux Pinning ◽  
Electron Backscatter Diffraction ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Scaling Analysis ◽  
Linear Behavior ◽  
Magnetic Hysteresis Loops ◽  
Grain Boundary Pinning ◽  
Backscatter Diffraction ◽  
Pinning Properties

The flux pinning properties of reacted-and-pressed Ba0.6K0.4Fe2As2 powder were measured using magnetic hysteresis loops in the temperature range 20 K ≤ T ≤ 35 K. The scaling analysis of the flux pinning forces ( F p = j c × B , with j c denoting the critical current density) following the Dew-Hughes model reveals a dominant flux pinning provided by normal-conducting point defects ( δ l -pinning) with only small irreversibility fields, H irr , ranging between 0.5 T (35 K) and 16 T (20 K). Kramer plots demonstrate a linear behavior above an applied field of 0.6 T. The samples were further characterized by electron backscatter diffraction (EBSD) analysis to elucidate the origin of the flux pinning. We compare our data with results of Weiss et al. (bulks) and Yao et al. (tapes), revealing that the dominant flux pinning in the samples for applications is provided mainly by grain boundary pinning, created by the densification procedures and the mechanical deformation applied.

MAGNETIC PROPERTIES OF THE HIGH Tc SUPERCONDUCTORS BiSrCaCuO AND TlBaCaCuO

1989 ◽  
Vol 03 (01) ◽  
pp. 77-85 ◽  
Author(s):  
Y. D. DAI ◽  
C. LIN ◽  
W. B. ZHANG ◽  
S. Q. FENG ◽  
X. ZHU ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Flux Pinning ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
High Tc Superconductors ◽  
Magnetic Current ◽  
High Tc ◽  
Bean Model ◽  
Current Densities ◽  
Magnetic Hysteresis Loops

Magnetic properties of the high T c superconductors BiSrCaCuO and TlBaCaCuO were investigated systematically. Magnetic current densities were calculated from magnetic hysteresis loops of bulk and powdered samples by Bean model. The results showed that flux pinning in these materials is much weaker than that in YBaCuO.

FLUX PINNING PROPERTIES AND MAGNETIC RELAXATION OF SUPERCONDUCTING SmFe0.9Co0.1AsO

2012 ◽  
Vol 26 (30) ◽  
pp. 1250197 ◽  
Author(s):  
J. C. ZHUANG ◽  
Y. SUN ◽  
Y. DING ◽  
F. F. YUAN ◽  
J. T. LIU ◽  
...  
Keyword(s):  
Critical Current ◽  
Magnetic Relaxation ◽  
Flux Pinning ◽  
Magnetic Hysteresis ◽  
Resistivity Measurement ◽  
Hysteresis Loops ◽  
Theoretical Models ◽  
Current Densities ◽  
First Time ◽  
Pinning Properties

Magnetic Co ion doped SmFeAsO polycrystal was synthesized via solid-state reaction. Resistivity, SEM and magnetic hysteresis loops (MHLs) were measured to investigate magnetic properties of the sample. Critical current densities as well as the flux pinning forces densities were estimated from MHLs. This paper reports for the first time the research of superconducting MHLs as well as magnetic relaxation properties of SmFe 0.9 Co 0.1 AsO . Results suggest that: (i) A tail effect in the resistivity measurement together with the rapid decrease in critical current densities at low fields shows the evidence for granularity of the sample; (ii) The asymmetry of the MHLs may be caused by the Bean–Livingstone (BL) surface pinning or granular nature, and none of theoretical models are suitable to the scaling behaviors of flux pinning forces densities; (iii) The anomalous tendency of the temperature dependence of magnetic relaxation rate as well as the effective pinning energy were observed, which may be attributed to the competition between the bulk pinning and the BL surface pinning.

Simulations of magnetic hysteresis loops at high temperatures

2014 ◽  
Vol 116 (12) ◽  
pp. 123910 ◽  
Author(s):  
M. L. Plumer ◽  
J. van Ek ◽  
J. P. Whitehead ◽  
T. J. Fal ◽  
J. I. Mercer
Keyword(s):  
High Temperatures ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Magnetic Hysteresis Loops

scholarly journals Exchange bias in ferromagnetic bilayers with orthogonal anisotropies: the case of GaMnAsP/GaMnAs combination

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Suho Choi ◽  
Seul-Ki Bac ◽  
Xinyu Liu ◽  
Sanghoon Lee ◽  
Sining Dong ◽  
...  
Keyword(s):  
Exchange Bias ◽  
Easy Axis ◽  
Initial Conditions ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
The Other ◽  
Planar Hall Effect ◽  
Magnetic Layers ◽  
Out Of Plane ◽  
Magnetic Hysteresis Loops

Abstract We report the observation of exchange bias in a ferromagnetic Ga0.94Mn0.06As0.77P0.23/ Ga0.94Mn0.06As bilayer, in which the easy axis in one layer is oriented out-of-plane, and in the other in-plane. Magnetization reversal in this system is explored using planar Hall effect (PHE) measurements under various initial conditions and with various field-cooling orientations. Our results show that the two magnetic layers are ferromagnetically exchange-coupled, and that such coupling results in pronounced exchange-bias-like shifts of magnetic hysteresis loops during reversal of in-plane magnetization. The presence of exchange bias in this system can be understood on the basis of magnetic closure domains formed in the layer with the out-of-plane easy axis.

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