SMALL HYSTERESIS LOOPS INVESTIGATIONS ON HIGH Tc OXIDE SUPERCONDUCTORS

1991 ◽  
Vol 05 (18) ◽  
pp. 1237-1248
Author(s):  
J. SOSNOWSKI ◽  
J. RAABE ◽  
E. BOBRYK ◽  
A. GILEWSKI ◽  
J. WARCHULSKA
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
High Temperature ◽  
Theoretical Model ◽  
Magnetic Field Dependence ◽  
Numerical Approximation ◽  
Hysteresis Loops ◽  
Oxide Superconductors ◽  
High Tc ◽  
Fitting Procedure

Results of investigations on small hysteresis loops of yttrium-based high temperature ceramical compounds are presented. A proposed theoretical model describing the magnetic induction profile in a sample has been used for numerical approximation of the experimental data. The results of this fitting procedure then allow one to obtain detailed information on the pinning force's magnetic field dependence as well as the critical current of ceramical compounds.

Magnetic Coupling in La0.7Ca0.3MnO3/YBa2Cu3O7/La0.7Ca0.3MnO3 Trilayers

2009 ◽  
Vol 289-292 ◽  
pp. 303-309
Author(s):  
N.M. Nemes ◽  
C. Visani ◽  
J. Garcia-Barriocanal ◽  
F.Y. Bruno ◽  
Z. Sefrioui ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Temperature ◽  
Carrier Density ◽  
High Temperature Superconductor ◽  
Hysteresis Loops ◽  
Magnetic Coupling ◽  
Oxygen Depletion ◽  
Free Carrier ◽  
Half Metallic ◽  
Free Carrier Density

We report on the interplay between ferromagnetism and superconductivity in trilayers La0.7Ca0.3MnO3/YBa2Cu3O7/La0.7Ca0.3MnO3 made of half metallic manganite and high temperature superconductor cuprate. Samples with a fully oxygenated cuprate show a magnetic field interval where the magnetizations of the manganite are aligned antiparallel. A considerable magnetoresistance accompanies the switching between magnetization configurations (parallel vs. antiparallel) of the manganite moments. Suppression of the free carrier density of the cuprate which occurs upon oxygen depletion, results in deep modifications in the shape of the normal state hysteresis loops indicating that there may be a magnetic coupling mediated by free carrier density of the cuprate. This result outlines the importance of quasiparticle transmission in the interplay between ferromagnetism and superconductivity in this kind of samples.

Underplatform Dampers for Turbine Blades: Theoretical Modeling, Analysis, and Comparison With Experimental Data

1998 ◽  
Vol 123 (4) ◽  
pp. 919-929 ◽  
Author(s):  
K. Y. Sanliturk ◽  
D. J. Ewins ◽  
A. B. Stanbridge
Keyword(s):  
Experimental Data ◽  
Theoretical Model ◽  
Normal Load ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Hysteresis Loops ◽  
Modeling Analysis ◽  
Modes Of Vibration ◽  
Opening And Closing ◽  
Distinct Features

This paper describes a theoretical model for analyzing the dynamic characteristics of wedge-shaped underplatform dampers for turbine blades, with the objective that this model can be used to minimize the need for conducting expensive experiments for optimizing such dampers. The theoretical model presented in the paper has several distinct features to achieve this objective including: (i) it makes use of experimentally measured contact characteristics (hysteresis loops) for description of the basic contact behavior of a given material combination with representative surface finish, (ii) the damper motion between the blade platform locations is determined according to the motion of the platforms, (iii) three-dimensional damper motion is included in the model, and (iv) normal load variation across the contact surfaces during vibration is included, thereby accommodating contact opening and closing during vibration. A dedicated nonlinear vibration analysis program has been developed for this study and predictions have been verified against experimental data obtained from two test rigs. Two cantilever beams were used to simulate turbine blades with real underplatform dampers in the first experiment. The second experiment comprised real turbine blades with real underplatform damper. Correlation of the predictions and the experimental results revealed that the analysis can predict (i) the optimum damping condition, (ii) the amount of response reduction, and (iii) the natural frequency shift caused by friction dampers, all with acceptable accuracy. It has also been shown that the most commonly used underplatform dampers in practice are prone to rolling motion, an effect which reduces the damping in certain modes of vibration usually described as the lower nodal diameter bladed-disk modes.

HIGH MAGNETIC FIELD HALL EFFECT AND MAGNETORESISTANCE STUDIES OF Y-Ba-Cu-O: A HIGH Tc SUPERCONDUCTOR

1987 ◽  
Vol 01 (02) ◽  
pp. 413-417
Author(s):  
J.D. Hettinger ◽  
A.G. Swanson ◽  
J.S. Brooks ◽  
Y.P. Ma
Keyword(s):  
Magnetic Field ◽  
High Temperature ◽  
Transition Temperature ◽  
Hall Effect ◽  
High Temperature Superconductor ◽  
Strong Dependence ◽  
Zero Magnetic Field ◽  
High Tc ◽  
Relative Percentage ◽  
High Tc Superconductor

We have measured the transition temperature, critical field, magnetoresistance, and Hall effect for the high temperature superconductor Y-Ba-Cu-O in magnetic fields up to 23T in the temperature range 4.2 to 125K. Meissner studies at zero magnetic field were also performed in some cases. We find a strong dependence of these parameters on the relative percentage of the correct phase of Y-Ba-Cu-O in the sample. We report new results on magnetoresistance and Hall effect in these materials.

scholarly journals Magnetic field dependence of Josephson photoresponse in high-Tc superconductor thin films

1994 ◽  
Vol 89 (8) ◽  
pp. 705-708 ◽  
Author(s):  
Gi. Schneider ◽  
P.G. Huggard ◽  
T.P. O'Brien ◽  
W. Blau ◽  
W. Prettl
Keyword(s):  
Magnetic Field ◽  
Thin Films ◽  
Field Dependence ◽  
Magnetic Field Dependence ◽  
High Tc ◽  
High Tc Superconductor ◽  
Superconductor Thin Films

TEMPERATURE AND MAGNETIC FIELD DEPENDENCE OF CRITICAL CURRENT OF YBaCuO JOSEPHSON JUNCTIONS

1987 ◽  
Vol 01 (02) ◽  
pp. 583-586 ◽  
Author(s):  
Peng Gao ◽  
Hongchang Fan ◽  
Xixian Yao ◽  
Zheng Yu ◽  
Shiying Ding ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Critical Current ◽  
Field Dependence ◽  
Josephson Junctions ◽  
Magnetic Field Dependence ◽  
High Tc ◽  
High Tc Superconductor

Josephson junctions were fabricated using high Tc superconductor. The I-V characteristics of the junctions were measured at liquid N2 temperature. The temperature and magnetic field dependence of the critical current were obtained and compared with theories.

EFFECT OF MAGNETIC FIELD ON PROPERTIES OF MR FLUIDS

2005 ◽  
Vol 19 (01n03) ◽  
pp. 597-601 ◽  
Author(s):  
J. HUANG ◽  
J. Q. ZHANG ◽  
J. N. LIU
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
Theoretical Model ◽  
Yield Stress ◽  
Applied Magnetic Field ◽  
Mr Fluids ◽  
Magnetic Chain ◽  
Viscoplastic Properties

The yield stress is one of the most important parameters that characterize viscoplastic properties of magnetorheological (MR) fluids. Based on the microstructure of magnetic-chain a theoretical model is developed to analyze the effect of the applied magnetic field on the yield stress. It has been shown that the values of the yield stress calculated by the model agree well with the experimental data.

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