Transport Measurements on Superconducting YBa2Cu3O7-δ Thin Film Lines

1989 ◽  
Vol 169 ◽  
Author(s):  
B. H. Moeckly ◽  
D. K. Lathrop ◽  
G. F. Redinbo ◽  
S. E. Russek ◽  
R. A. Buhrman
Keyword(s):  
Magnetic Field ◽  
Thin Film ◽  
Critical Current ◽  
Weak Link ◽  
High Sensitivity ◽  
Weak Links ◽  
Microwave Response ◽  
Field Response ◽  
Current Densities ◽  
Iv Curves

AbstractCritical current densities, magnetic field response, and microwave response have been measured for laser ablated YBa2Cu3O7-δ thin film lines on MgO and SrTiO3 substrates. Films on SrTiO3 have critical current densities > 1 x 106 A/cm2 at 77K and show uniform transport properties in lines of all sizes. Films on MgO have critical current densities which range between 102 and 106 A/cm2 at 77K and show considerable variation from device to device on the same chip. Narrow lines on MgO with low critical current densities show Josephson weak link structure which includes RSJ-like IV curves, microwave induced constant voltage steps, and a high sensitivity to magnetic field. The presence of the Josephson weak links is correlated with small amounts of misaligned grains in films on MgO.

Estimation of Local Current Transport Properties in Thin Film Superconductor Based on Scanning Hall-probe Microscopy

2012 ◽  
Vol 1434 ◽  
Author(s):  
Kohei Higashikawa ◽  
Kei Shiohara ◽  
Masayoshi Inoue ◽  
Takanobu Kiss ◽  
Masateru Yoshizumi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Thin Film ◽  
Critical Current Density ◽  
Electric Field ◽  
Critical Current ◽  
Current Density ◽  
Limiting Factors ◽  
Hall Probe ◽  
Scanning Hall Probe Microscopy ◽  
Field Criterion

ABSTRACTTo enhance a global critical current in a superconductor, it is indispensable to understand current limiting factors and their influence on such a critical current. From this point of view, we have investigated in-plane distribution of local critical current density and its electric field criterion in a thin-film superconductor by using scanning-Hall probe microscopy. In a remanent state, after the application of sufficiently high magnetic field to a sample, current flows at critical current density according to the critical state model. Such distribution of current density was estimated from that of measured magnetic field using the Biot-Savart law. Furthermore, the corresponding electric field criterion was evaluated from the relaxation of such remanent magnetic field by considering Faraday’s law. This means that we could estimate in-plane distribution of local critical current density as a function of electric field criterion in a nondestructive manner. This characterization method would be very helpful for finding current limiting factors in a thin-film superconductor and their influence on its global current density versus electric field properties which would usually be obtained by four-probe method.

DOUBLE STEP BEHAVIOR OF THE CRITICAL CURRENT VERSUS MAGNETIC FIELD IN A BULK JOSEPHSON MEDIUM

1994 ◽  
Vol 08 (24) ◽  
pp. 1483-1491 ◽  
Author(s):  
A.I. D’YACHENKO
Keyword(s):  
Magnetic Field ◽  
Critical Current ◽  
Weak Link ◽  
Surface Current ◽  
Double Step ◽  
Plateau Region ◽  
Josephson Medium ◽  
Metal Ceramic ◽  
Current Value ◽  
Link Model

This paper discusses the physics of the influence of a strong magnetic field H on the high T c metal ceramic critical current J c . The problem of boundary conditions for a surface current value in hard superconductors is analyzed. It is shown that if Abrikosov vortices in granules are rigidly pinned, the J c vs H dependence has a plateau region of relatively constant critical current. The hysteresis of ceramic critical current is calculated on the basis of the Josephson weak link model.

(001) grain boundaries in Ag-clad Bi2Sr2Ca1Cu2O8+y (BSCCO) tapes

1991 ◽  
Vol 49 ◽  
pp. 1088-1089
Author(s):  
Y. Feng
Keyword(s):  
Grain Boundaries ◽  
Cuprate Superconductors ◽  
Weak Link ◽  
Weak Field ◽  
Weak Links ◽  
Great Promise ◽  
Core Thickness ◽  
Current Densities ◽  
Powder In Tube ◽  
Very High

Recently, Ag-clad tapes of Bi-cuprate superconductors have shown great promise for application as conductors in very high magnetic fields at temperature 4-20 K. High critical current densities (Jc) with weak field dependence indicate that the powder-in-tube process can drastically reduce the effect of grain boundary weak links at 4-20 K. It is thus of great interest to study the grain boundaries in the Ag-clad BSCCO tapes to understand their effect on the Jc.BSCCO Ag-clad wires with 2:2:1:2 starting composition were drawn and rolled to rectangular tapes (0.1 x 3 mm) with BSCCO core thickness of 45μm. The sample was heated at 920°C for 15 minutes, cooled to 840°C at 10°C/h, then annealed at 840°C for 70 h. The measured Jc values exceed 2x104 A/cm2 (5T, 4.2K) and do not exhibit obvious weak link behaviour. In order to investigate the (001) grain boundaries, samples were made by bonding several tapes together along their broad face. Thin longitudinal slices were cut and then ion milled at 4.5 kV in liquid nitrogen. TEM was carried out by using a JEOL 200CX-II at 200 kV.

Angular Dependence of Magnetic Field on Critical Current Density in Tl2Ba2Ca2Cu3Ox Thin Film

1991 ◽  
pp. 555-558
Author(s):  
Toshihide Nabatame ◽  
Yukio Saito ◽  
Katsuzo Aihara ◽  
Tomoichi Kamo ◽  
Shin-Pei Matsuda
Keyword(s):  
Magnetic Field ◽  
Thin Film ◽  
Critical Current Density ◽  
Critical Current ◽  
Angular Dependence ◽  
Current Density
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