MICROWAVE ABSORPTION AND HIGH-FIELD JOSEPHSON MAGNETIC RESONANCE IN HIGH-Tc SUPERCONDUCTORS

2007 ◽  
Vol 21 (15) ◽  
pp. 903-908
Author(s):  
L. V. BELEVTSOV ◽  
A. I. D'YACHENKO ◽  
A. A. KOSTIKOV
Keyword(s):  
Magnetic Resonance ◽  
Microwave Absorption ◽  
Coupling Strength ◽  
High Field ◽  
Vortex Matter ◽  
High Tc Superconductors ◽  
High Tc ◽  
Pinning Centers ◽  
Grain Sizes ◽  
Vortex Separation

The possibility of high-field Josephson magnetic resonance (HFJMR) in high-T c superconductors (HTSCs) is theoretically demonstrated. The HFJMR is caused by the penetration of Abrikosov vortices into the grains in fields within H c1 ≤H<Hx (where H c1 is the first critical field and Hx is the field corresponding to vortex separation from pinning centers in the grains). The signals from microwave absorption is dependent on the ratio of grain sizes that produces junction, the anisotropy and the intergrain coupling strength. These properties can be used for investigations of HTSC macrostructures and a vortex matter.

Direct Determination of the Velocity of Vortices in High-Tc Superconductors by a Non-Equilibrium Method

1998 ◽  
Vol 12 (29n31) ◽  
pp. 3288-3291
Author(s):  
I. Kirschner ◽  
R. Laiho ◽  
A. C. Bódi ◽  
E. Lähderanta ◽  
I. Vajda
Keyword(s):  
Magnetic Field ◽  
Temperature Gradient ◽  
Vortex Motion ◽  
Direct Determination ◽  
Field Investigation ◽  
High Tc Superconductors ◽  
High Tc ◽  
Pinning Centers ◽  
Non Equilibrium

As is shown, thermally assisted vortex motion can come into being in high-T c superconductors due to the applied temperature gradient. Its behavior strongly depends on the local and global microstructure of the samples, moreover on the temperature and magnetic field. Investigation of the density, size and intensity of the pinning centers of specimens leads to the conclusion that the higher homogeneity immediately weakens and the lower one strenghtens the pinning, thus the former promotes and the latter impedes the vortex motion. The non-equilibrium experimental technique together with a.c. susceptibility measurements render possible the direct determination of the velocity of vortices. Depending on the actual microstructural state of samples it has the values between 6 × 10-2 mm/s and 18 × 10-2 mm/s in the case of Y-Ba-Cu-O specimens investigated.

scholarly journals RECENTI SVILUPPI NELLA RISONANZA MAGNETICA NUCLEARE A PAVIA

2021 ◽  
Author(s):  
Marta Filibian ◽  
Pietro Carretta
Keyword(s):  
Magnetic Resonance ◽  
Materials Science ◽  
Condensed Matter ◽  
Risonanza Magnetica ◽  
Molecular Magnets ◽  
Food Science ◽  
Resonance Imaging ◽  
High Tc Superconductors ◽  
High Tc ◽  
The University

Nuclear Magnetic Resonance (NMR) is a crucial experimental technique for the study of matter in several fields and applications, as for example in physics, chemistry, materials science, biology, medicine and food science. By means of this technique, the NMR group of the University of Pavia (UniPV) has given valuable scientific contributions to the Condensed Matter Physics and to the Physics applied to the Biomedical sector. In this note we’ll illustrate some of the most relevant results produced by the researchers of the group within decades of work carried out with passion and dedication, with examples regarding the Molecular Magnets, the High Tc Superconductors, the contrast agents and the hyperpolarization of molecules for Magnetic Resonance Imaging. We’ll also report some preliminary results obtained at the Preclinical Imaging Facility of UniPV, recently founded with the key contribution of the NMR group.

APPLICATION OF ESR TO HIGH-Tc SUPERCONDUCTORS AND RELATED MATERIALS IV: ALKALI K DOPING EFFECTS ON THE SUPERCONDUCTING CHARACTERISTICS OF K3C60

1999 ◽  
Vol 13 (02) ◽  
pp. 59-69
Author(s):  
K. SUGAWARA ◽  
N. OHYA ◽  
N. ARAI ◽  
S. ICHIMURA ◽  
K. YAMAMOTO ◽  
...  
Keyword(s):  
Microwave Absorption ◽  
Calcination Temperature ◽  
Volume Fraction ◽  
Superconducting Properties ◽  
High Tc Superconductors ◽  
High Tc ◽  
Doping Effects ◽  
Superconducting Volume Fraction ◽  
Vortex Size ◽  
Quartz Tubes

Several samples of K 3 C 60 have been made by the calcination of C 60 powder plus K flakes in evacuated quartz tubes at temperatures between 100°C and 700°C for 24 hours. The non-resonant microwave absorption (NRMA) measurements have been done below T c for these samples. From the linewidths and intensities of the NRMA signals, the superconducting properties (T c superconducting volume fraction and vortex size) have been studied as a function of the calcination temperature.

MICROWAVE ABSORPTION STUDIES ON HIGH-Tc SUPERCONDUCTORS AND RELATED MATERIALS VI—NON-RESONANT MICROWAVE ABSORPTION IN ULTRA-THIN Bi-Sr-Ca-Cu-O FILMS—

1992 ◽  
Vol 06 (05) ◽  
pp. 265-272 ◽  
Author(s):  
K. SUGAWARA ◽  
T. SUGIMOTO ◽  
D.J. BAAR ◽  
Y. SHIOHARA ◽  
S. TANAKA
Keyword(s):  
Magnetic Field ◽  
Microwave Absorption ◽  
Signal Intensity ◽  
Critical Magnetic Field ◽  
High Tc Superconductors ◽  
Temperature Relation ◽  
High Tc ◽  
Absorption Studies ◽  
Increasing Temperature ◽  
Mgo Substrate

Non-resonant microwave absorption (NRMA) studies have been done for Bi-Sr-Ca-Cu-O (BSCCO) films with thicknesses of 30 Å and 15 Å fabricated on MgO substrate by MOCVD. For the latter two kinds of samples have been fabricated: BSCCO/MgO and BiOx/BSCCO/MgO . NRMA signals have been detected up to about 70–75 K for all the samples. The lower critical magnetic field H c1 * of the 30 Å film was severely increased by the application of a magnetic field of several kGauss, whereas it is almost unaffected in the case of 15 Å films. H c1 * increases but the signal intensity decreases with increasing temperature for all the 30 Å and 15 Å samples. The temperature dependence of the intensity is quite different from that of thicker films (100 Å and 350 Å), in which the intensity vs. temperature relation has a peak (or peaks) at particular temperature(s).

MICROWAVE ABSORPTION STUDIES ON HIGH-Tc SUPERCONDUCTORS AND RELATED MATERIALS I—LOW-FIELD MICROWAVE ABSORPTION IN A BiSrCaCuO THIN FILM DEPOSITED BY MOCVD

1991 ◽  
Vol 05 (09) ◽  
pp. 667-674 ◽  
Author(s):  
K. SUGAWARA ◽  
T. SUGIMOTO ◽  
K. YASUIKE ◽  
D.J. BAAR ◽  
Y. SHIOHARA ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Thin Film ◽  
Microwave Absorption ◽  
Applied Field ◽  
Film Plane ◽  
Experimental Results ◽  
High Tc Superconductors ◽  
High Tc ◽  
Low Field ◽  
Absorption Studies

Non-resonant microwave absorption as a function of temperature and magnetic field has been studied in a Bi-Sr-Ca-Cu-O film prepared by MOCVD. A maximum in the absorption as a function of temperature was observed at approximately 60 K. An average Josephson loop diameter of about 0.9~1.5 microns was inferred from the experimental results. The absorption was found to depend on the angle of the film plane relative to the applied field.

Effect of Disorder on Driven Vortex Matter in High-Tc Superconductors

2003 ◽  
Vol 17 (18n20) ◽  
pp. 3433-3435
Author(s):  
Qing-Hu Chen ◽  
Xiao Hu
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Xy Model ◽  
Vortex Matter ◽  
High Tc Superconductors ◽  
High Tc ◽  
First Order Phase Transition ◽  
Effect Of Disorder ◽  
First Order Phase ◽  
Large Scale Simulations

We performed large-scale simulations in the current-driven three-dimensional frustrated anisotropic XY model in the presense of point-like defects with resistively-shunted junction dynamics. A moving Bragg (BrG) glass is observed applying the current in the equilibrium BrG state. The first-order phase transition from the moving BrG to the moving smectic is clarified. The effect of disorder become weak once the vortex matter is set in motion.

Temperature dependence of the low field microwave absorption of high Tc superconductors

1988 ◽  
Vol 133 (6) ◽  
pp. 339-341 ◽  
Author(s):  
A.R. Harutyunyan ◽  
L.S. Grigoryan ◽  
M. Baran ◽  
S. Piechota
Keyword(s):  
Temperature Dependence ◽  
Microwave Absorption ◽  
High Tc Superconductors ◽  
High Tc ◽  
Low Field

MICROWAVE ABSORPTION STUDIES ON HIGH-Tc SUPERCONDUCTORS AND RELATED MATERIALS VII — ESR OF DPPH COATED ON A THIN BiSrCaCuO FILM FABRICATED ON MgO(100) SUBSTRATE

1992 ◽  
Vol 06 (11) ◽  
pp. 675-682
Author(s):  
K. SUGAWARA ◽  
T. SUGIMOTO ◽  
Y. SHIOHARA ◽  
S. TANAKA
Keyword(s):  
Magnetic Field ◽  
Critical Current Density ◽  
Temperature Dependence ◽  
Microwave Absorption ◽  
Current Density ◽  
Applied Magnetic Field ◽  
High Tc Superconductors ◽  
High Tc ◽  
Absorption Studies ◽  
Mpmg Method

ESR of DPPH coated on a Bi-Sr-Ca-Cu-O (BSCCO) film (350 Å thick) fabricated on MgO(100) substrate by MOCVD was studied. Temperature dependence of the ESR peak-to-peak linewidth, ΔH pp , and the effect of applied magnetic field on ΔH pp have been studied below about 100 K. The results were compared with those of ESR of DPPH coated on ceramic Y-Ba-Cu-O samples (powder and bulk) made by the MPMG method. The DPPH ESR for the BSCCO film revealed that ΔH pp was independent of applied magnetic field up to about 9 kG. In addition, no similarity between the temperature dependence of the excess ESR linewidth of the DPPH and that of critical current density was found for the BSCCO film. These results for the BSCCO film are different from those for the MPMG YBCO samples.

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