scholarly journals The onset of dissipation in high-temperature superconductors: magnetic hysteresis and field dependence

2020 ◽  
Author(s):  
EF Talantsev ◽  
Nicholas Strickland ◽  
Stuart Wimbush ◽  
Justin Brooks ◽  
AE Pantoja ◽  
...  
Keyword(s):  
High Temperature ◽  
Electric Field ◽  
High Temperature Superconductors ◽  
Magnetic Hysteresis ◽  
Threshold Current ◽  
Critical Currents ◽  
Magnetic Flux Density ◽  
Perpendicular Component ◽  
Definition Of ◽  
Field Criterion

© 2018, The Author(s). Recently, we showed that the self-field transport critical current, Ic(sf), of a superconducting wire can be defined in a more fundamental way than the conventional (and arbitrary) electric field criterion, Ec = 1 μV/cm. We defined Ic(sf) as the threshold current, Ic,B, at which the perpendicular component of the local magnetic flux density, B⊥, measured at any point on the surface of a high-temperature superconducting tape abruptly crosses over from a non-linear to a linear dependence with increasing transport current. This effect results from the current distribution across the tape width progressively transitioning from non-uniform to uniform. The completion of this progressive transition was found to be singular. It coincides with the first discernible onset of dissipation and immediately precedes the formation of a measureable electric field. Here, we show that the same Ic,B definition of critical currents applies in the presence of an external applied magnetic field, Ba. In all experimental data presented here Ic,B is found to be significantly (10–30%) lower than Ic,E determined by the common electric field criterion of Ec = 1 µV/cm, and Ec to be up to 50 times lower at Ic,B than at Ic,E.

scholarly journals The onset of dissipation in high-temperature superconductors: magnetic hysteresis and field dependence

2020 ◽  
Author(s):  
EF Talantsev ◽  
Nicholas Strickland ◽  
Stuart Wimbush ◽  
Justin Brooks ◽  
AE Pantoja ◽  
...  
Keyword(s):  
High Temperature ◽  
Electric Field ◽  
High Temperature Superconductors ◽  
Magnetic Hysteresis ◽  
Threshold Current ◽  
Critical Currents ◽  
Magnetic Flux Density ◽  
Perpendicular Component ◽  
Definition Of ◽  
Field Criterion

© 2018, The Author(s). Recently, we showed that the self-field transport critical current, Ic(sf), of a superconducting wire can be defined in a more fundamental way than the conventional (and arbitrary) electric field criterion, Ec = 1 μV/cm. We defined Ic(sf) as the threshold current, Ic,B, at which the perpendicular component of the local magnetic flux density, B⊥, measured at any point on the surface of a high-temperature superconducting tape abruptly crosses over from a non-linear to a linear dependence with increasing transport current. This effect results from the current distribution across the tape width progressively transitioning from non-uniform to uniform. The completion of this progressive transition was found to be singular. It coincides with the first discernible onset of dissipation and immediately precedes the formation of a measureable electric field. Here, we show that the same Ic,B definition of critical currents applies in the presence of an external applied magnetic field, Ba. In all experimental data presented here Ic,B is found to be significantly (10–30%) lower than Ic,E determined by the common electric field criterion of Ec = 1 µV/cm, and Ec to be up to 50 times lower at Ic,B than at Ic,E.

Transport Properties over Critical Currents for Ag-Sheathed Bi2Sr2CaCu2O8 Superconductors with Different E-J Dependence

2006 ◽  
Vol 47 ◽  
pp. 118-123 ◽  
Author(s):  
K. Watanabe ◽  
T. Inoue ◽  
Satoshi Awaji ◽  
Gen Nishijima ◽  
Ken Ichiro Takahashi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Heat Treatment ◽  
High Temperature ◽  
Electric Field ◽  
Current Density ◽  
High Temperature Superconductors ◽  
Grain Morphology ◽  
Critical Currents ◽  
Heat Treated ◽  
The Magnetic Field

The current-carrying properties beyond a critical current determined by a voltage criterion for Ag-sheathed Bi2Sr2CaCu2O8 (Ag/Bi2212) superconductors are examined at 10 K and 20 K in magnetic fields. We prepared the in-field heat-treated Ag/Bi2212 wires, in order to obtain the magnetic field alignment microstructure for Ag/Bi2212. The electric field and current density (E-J) properties were evaluated for Ag/Bi2212 wires with and without the in-field heat-treatment. We found that the E-J properties for the in-field heat-treated Ag/Bi2212 wires differ from those for the out-of-field heat-treated ones, and are analogous to the E-J dependence for Bi-system high temperature superconductors with the sintered-like grain morphology.

Limits to critical currents in high-temperature superconductors: What we can learn from tailored defects

1992 ◽  
Author(s):  
D. K. Christen ◽  
J. R. Thompson ◽  
H. R. Kerchner ◽  
B. C. Sales ◽  
B. C. Chakoumakos ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperature Superconductors ◽  
Critical Currents

Crystal Growth, Structure, and Incoherent Metallic Behaviour of FeCrAs

2011 ◽  
Vol 170 ◽  
pp. 276-281 ◽  
Author(s):  
Wen Long Wu ◽  
Alix McCollam ◽  
Ian P. Swainson ◽  
Stephen R. Julian
Keyword(s):  
High Temperature ◽  
High Temperature Superconductivity ◽  
High Temperature Superconductors ◽  
Magnetic Hysteresis ◽  
Freezing Temperature ◽  
Growth Structure ◽  
Preparation Conditions ◽  
Scattering Rate ◽  
Spin Freezing ◽  
Low Levels

There is growing interest in a possible connection between incoherent metallic conduction and high temperature superconductivity, that is exemplified by the behaviour of the parent compounds of the new iron-pnictide high-temperature superconductors. We have recently discovered very incoherent behaviour in the non-superconducting arsenide, FeCrAs. This material shows a non-metallic resistivity that rises with decreasing temperature without saturation or a gap, over three decades of temperature, from 80 mK to 800 K. We briefly review this behaviour, and address the question of disorder: how to test for the presence of disorder in a system where the scattering rate inferred from the resistivity is highly abnormal, and how to produce single crystals with low levels of disorder. Our discussion will focus on magnetic properties. FeCrAs is a partly frustrated magnetic system with a Nèel temperature TN that depends on sample quality, a sample-dependent spin freezing temperature TF < TN, and magnetic hysteresis that depends strongly on preparation conditions due to ferromagnetic minority phases in disordered samples.

Dynamical Properties of Weakly Coupled Josephson Systems

1990 ◽  
Vol 195 ◽  
Author(s):  
K. H. Lee ◽  
T.-K. Xia ◽  
D. Stroud
Keyword(s):  
High Temperature ◽  
Magnetic Fields ◽  
Harmonic Generation ◽  
Finite Temperature ◽  
Josephson Junctions ◽  
High Temperature Superconductors ◽  
Dynamical Behavior ◽  
Critical Currents ◽  
Weakly Coupled ◽  
Dynamical Properties

ABSTRACTWe review recent work on the dynamical behavior of coupled resistively-shunted Josephson junctions, with emphasis on our own calculations. We present a model which allows for the inclusion of finite temperature, disorder, d.c. and a. c. applied currents, and applied magnetic fields. We discuss applications to (a) calculations of critical currents and IV characteristics; (b) harmonic generation and microwave absorption by finite clusters of Josephson junctions; (c) critical energies for vortex depinning; and (d) quantized voltage plateaus in arrays subjected to combined d.c. and a. c. currents. Possible connections to the behavior of granular high-temperature superconductors are briefly discussed.

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