Orientation Dependence of Flux Pinning in a Layered Bi2Sr2 Ca1 Cu2O8 + 10% Ag Composite

1991 ◽  
Vol 235 ◽  
Author(s):  
Maria Foldeaki ◽  
Hassel Ledbetter
Keyword(s):  
Transition Temperature ◽  
Low Temperatures ◽  
Grain Orientation ◽  
Orientation Dependence ◽  
Zero Field ◽  
Pinning Force ◽  
Superconducting Transition ◽  
Two Phase ◽  
Random Direction ◽  
Strong Pinning

ABSTRACTThe Bi2 Sr2 Ca1 Cu2 O8 + 10% Ag specimen was grain oriented along the a(b) axis, but random in the perpendicular plane. Magnetic susceptibility and hysteresis measured along the axis of grain orientation and in the polycrystalline direction showed remarkable anisotropy. At low temperatures (below about 30 K), hysteresis curves were compatible with the strong-pinning model. The pinning force calculated from the hysteresis loop showed a higher maximum in the random direction, but decreased fast with increasing field and temperature. From the zero-field-cooled (zfc) and field-cooled (fc) susceptibility curves, the irreversibility line T*(H*) was determined. Evaluation according to the de Almeida-Thouless equation with fixed exponent n=3/2 revealed a two-phase vortex structure; one nearly isotropic with low (40-$K) zero-field irreversibility transition temperature, and one strongly anisotropic, the irreversibility transition being close to the superconducting-transition temperature.

Electron Irradiation of YBa2Cu3O7 at low Temperatures

1987 ◽  
Vol 99 ◽  
Author(s):  
B. Stritzker ◽  
W. Zander ◽  
F. Dworschak ◽  
U. Poppe ◽  
K. Fischer
Keyword(s):  
Transition Temperature ◽  
Electron Irradiation ◽  
Normal State ◽  
Low Temperatures ◽  
Superconducting Transition Temperature ◽  
Superconducting Transition ◽  
Radiation Induced ◽  
State Resistance ◽  
Normal State Resistance

ABSTRACTBulk samples of YBa2Cu3O7−x have been homogenously irradiated with 3 MeV electrons at temperatures below 20 K. Whereas the superconducting transition temperature, Tc, drops dramatically with increasing dose the width of the transition remains unchanged (Δ Tc ≤ 1.5 K). The normal state resistance at 100 K increases substantially during the electron irradiation. Several irreproducible experiments can be interpreted with a radiation induced, unstable increase of Tc.

Amorphous Gallium Produced By Pulsed Excimer Laser Irradiation

1985 ◽  
Vol 51 ◽  
Author(s):  
J. Fröhlingsdorf ◽  
B. Stritzker
Keyword(s):  
Transition Temperature ◽  
Energy Density ◽  
Excimer Laser ◽  
Low Temperatures ◽  
Threshold Energy ◽  
Residual Resistivity ◽  
Superconducting Transition ◽  
Β Phase ◽  
Excimer Laser Irradiation ◽  
Vapor Quenching

ABSTRACTPure crystalline Ga films (α-Ga, β-Ga) have been irradiated at low temperatures (≤ 20 K) with an Excimer laser. By measuring the superconducting transition temperature Tc and the residual resistivity ≤o, the resulting Ga phases (α-Ga, β-Ga, a-Ga) can be identified.Both crystalline Ga phases can be transformed into the amorphous phase.The threshold energy density for the β→ a transition depends on the film thickness, whereas the α →. a transition occurs always at about 225 mJ/cm2 This behavior is in agreement with earlier observations that a-Ga can grow on top of the in-phase but not on the β-phase.The results of laser quenching are compared with other non-equilibrium techniques for the production of a-Ga, such as vapor quenching and low temperature ion iradiation.

Ultra-Low-Field Squid Magnetic Measurements on High Temperature Ceramic YBaCuO Superconductors

1987 ◽  
Vol 99 ◽  
Author(s):  
D. C. Cronemeyer ◽  
A. P. Malozemoff ◽  
T. R. Mcguire
Keyword(s):  
High Temperature ◽  
Transition Temperature ◽  
Ceramic Sample ◽  
Superconducting Transition Temperature ◽  
Magnetic Measurements ◽  
Zero Field ◽  
Superconducting Transition ◽  
Temperature Range ◽  
Low Field ◽  
The Difference

ABSTRACTWe report ultra-low-field (5 mOe - 1 Oe) magnetic measurements on a ceramic sample of YBaCuO. A positive remanent moment is observed which accurately equals the difference of the field-cooled and zero-field-cooled moments throughout the temperature range. At higher fields this relationship breaks down. A reversible region is observed near the superconducting transition temperature which is independent of field. These results are discussed in the context of recent models.

TRANSPORT PROPERTIES OF La2-x1Srx1CuO4+δ/La2-x2Srx2CuO4+δ MULTILAYERS GROWN BY LASER ABLATION

2013 ◽  
Vol 27 (15) ◽  
pp. 1362029
Author(s):  
H. F. WANG ◽  
Y. Z. ZHANG ◽  
L. H. LIU ◽  
D. P. LI ◽  
G. Y. WANG ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Laser Ablation ◽  
Transport Properties ◽  
Low Temperatures ◽  
Superconducting Transition Temperature ◽  
Dominant Factor ◽  
Deposition Condition ◽  
Superconducting Transition ◽  
Charge Redistribution ◽  
Transport Measurements

A series of La 2-x1 Sr x1 CuO 4+δ/ La 2-x2 Sr x2 CuO 4+δ multilayers were epitaxially grown on (001) LaSrAlO 4 and (001) SrTiO 3 substrates by laser ablation, where x1 = 0.0, 0.08 (underdoped) and x2 = 0.24, 0.32, 0.45 (over-doped). Before the depositions of each multilayer, all of the single layers were deposited and characterized, and then the multilayers were deposited by using the same deposition condition except shifting targets for laser ablation. These multilayers are highly c-axis oriented. Several modulation wavelengths of the sublayers were selected for preparing the multilayers. The resistance measurements of these single layered films of La 2-x1 Sr x1 CuO 4+δ, La 2-x2 Sr x2 CuO 4+δ, and multilayers of La 2-x1 Sr x1 CuO 4+δ/ La 2-x2 Sr x2 CuO 4+δ were performed and compared. The transport measurements suggest that the charge redistribution may be a dominant factor for the superconducting transition temperature in low temperatures.

Pinning Force and Time-Dependent Response in a Grain-Oriented Yttrium 1:2:3 Superconductor

1992 ◽  
Vol 275 ◽  
Author(s):  
M. Foldeaki ◽  
H. Ledbetter ◽  
R. C. O'Handley ◽  
J. Oti ◽  
T. Yamamoto
Keyword(s):  
Flux Line ◽  
Magnetic Hysteresis ◽  
Longitudinal Axis ◽  
Orientation Dependence ◽  
Time Dependent ◽  
Zero Field ◽  
Pinning Force ◽  
X Ray Diffraction ◽  
Flux Flow

ABSTRACTX-ray diffraction shows a preferred orientation of the 1:2:3 crystallites with the (ab) planes parallel to the longitudinal axis of the bar-shaped specimen, and a random orientation of the c axes. The dc magnetic hysteresis and time-dependent response were measured parallel to the (ab) planes or parallel to the random axis. The orientation dependence of the shape of the dc magnetic hysteresis proved the anisotropie nature of the flux-line structure and flux pinning. The experimental points were fitted to theoretical equations, allowing quantitative characterization of the orientation and temperature-dependent pinning. Time-dependent response was found to be logarithmic below a critical temperature in the range of 0.5 Tc. Activation energies determined in this region by assuming thermally assisted flux flow were found to be significantly higher than those in polycrystalline YBCO. Several activation processes or steps could be clearly distinguished. The field-cooled and zero-field-cooled specimens did not show significant differences, neither did the transport and magnetic critical current. This proves the presence of clean grain boundaries in this investigated high-quality sample.

Radiation Damage in YBa2Cu3O7 by Fast Neutrons

1987 ◽  
Vol 99 ◽  
Author(s):  
J. O. Willis ◽  
J. R. Cost ◽  
R. D. Brown ◽  
J. D. Thompson ◽  
D. E. Peterson
Keyword(s):  
Transition Temperature ◽  
Critical Current Density ◽  
Fast Neutron ◽  
Critical Current ◽  
Current Density ◽  
Superconducting Transition Temperature ◽  
Fast Neutrons ◽  
Zero Field ◽  
Superconducting Transition ◽  
Fast Neutron Irradiation

ABSTRACTThe superconducting transition temperature of sintered YBa2Cu3O7 decreases at a rate of 2.7 K/1018 n/cm2 (E > 0.1 MeV) for fast neutron irradiation. The critical current density Jc increases a factor of three at zero field and more than three at nonzero fields for fluences up to 2×1018 n/cm2. At both 7 and 75 K, Jc is decreasing with fluence near 3×1018 n/cm2.

DOPING AND TEMPERATURE DEPENDENCE OF SUPERFLUID DENSITY IN KINETIC ENERGY DRIVEN CUPRATE SUPERCONDUCTORS

2010 ◽  
Vol 24 (29) ◽  
pp. 2845-2854
Author(s):  
ZHEYU HUANG ◽  
HUAISONG ZHAO ◽  
SHIPING FENG
Keyword(s):  
Transition Temperature ◽  
Kinetic Energy ◽  
Temperature Dependence ◽  
Low Temperatures ◽  
Cuprate Superconductors ◽  
Superfluid Density ◽  
Linear Temperature Dependence ◽  
Superconducting Transition ◽  
Zero Temperature ◽  
Linear Temperature

Within the kinetic energy driven superconducting mechanism, the doping and temperature dependence of the superfluid density in cuprate superconductors is studied throughout the superconducting dome. It is shown that the superfluid density shows a crossover from the linear temperature dependence at low temperatures to a nonlinear one in the extremely low temperatures. In analogy to the dome-like shape of the doping dependent superconducting transition temperature, the maximal zero-temperature superfluid density occurs around the critical doping δ ≈ 0.195, and then decreases in both lower doped and higher doped regimes.

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