14 research outputs found
Investigation of the anisotropy of dissipation processes in single crystal of Yba2Cu3O7-d system
By means of contactless mechanical method of the measurement of energy losses
in superconductors, the anisotropy of dissipation processes has been studied in
single crystal high-temperature layered superconductors of Yba2Cu3O7-d system,
being in mixed state. The observed anisotropy of energy losses indicates the
possibility of the existence of the symmetry of order parameter of dx2-y2 type
in these single crystals.Comment: 4 pages, 3 figure
The investigation of EPR paramagnetic probe line width and shape temperature dependence in high-temperature superconductors of Bi–Pb–Sr–Ca–Cu–O system
The work is related with the finding out of magnetic phases in strongly anisotropic high-temperature superconductor Bi1,7Pb0,3Sr2Ca2Cu3O10-δ in the temperature region where the superconductor is in the normal state. It was studied the temperature dependence of the paramagnetic probe EPR line width. In the normal state at T\u3eTc near 175 K it was revealed a pick in the temperature dependence of line width. In this region it was observed the time increase of the line width with the characteristic time ~ 17 min. This shows the possibility of magnetic phase formation in this material
Effect of Secondary Echo Signals in Spin-Systems with a Large Inhomogeneous Broadening of NMR Line
The possibility of comparatively simple and fast determination of
characteristic relaxation parameters T1, T2 and T3 for nuclear spin-systems
with strong Larmor and Rabi inhomogeneous broadenings of NMR lines using the
secondary echo signal effect was experimentally shown. Resides, this method
gives opportunity to obtain a valuable infomation on the inhomogeneous NMR
broadening which reflects the character of magnetic field microscopic
destribution in such systems, as example, multidomain magnetics and
superconductors.Comment: 12 pages, 5 figure
On the Nature of Superconducting Precursors in Bi-Pb-Sr-Ca-Cu-O Compositions Fabricated by Hot Shock Wave Consolidation Technology
In this paper, the possibility of critical temperature increasing of superconducting precursor Tс and the current bearing capacity in samples of Bi-Pb-Sr-Ca-Cu-O superconducting system fabricated using hot shock wave consolidation (HSWC) technology and investigated by the vibrating torsional magnetometry method, was studied. The advantage of HSWC technology over the traditional technologies of superconducting composites synthesis is that the high-density materials are made from the Bi-Pb-Sr-Ca-Cu-O superconducting system. After the action of explosive wave the superconductivity is retained. After the explosion a pronounced texture is formed indicating the creation of efficient pinning centers and thus, the increase of current-carrying ability of the obtained material. The critical temperature of potential superconducting precursor Tc of transition to superconducting state increased from Tc=107K for starting sample to Tc=138K, using the HSWC technology for synthesis of samples in range of pressures from P=5GPa up to P=12GPa
Temperature dependence investigation of dissipation processes in strongly anisotropic high-temperature superconductors of Bi-Pb-Sr-Ca-Cu-O system synthesized using solar energy
The investigation of temperature dependence of damping and period of
vibrations of HTSC superconductive cylinder of Bi-Pb-Sr-Ca-Cu-O system
suspended by a thin elastic thread and performing axial-torsional vibrations in
a magnetic field at temperatures above the critical one for the main phase
Tc=107 K were carried out. It was observed some "chaos" temperature region in
the temperature interval 107-138 K, where it is seen separate ripples of
dissipation and oscillation frequency. It is assumed that the "chaos" region
could point to a possibility of existence of other magnetic and more
high-temperature phases as single islands in a normal materials matrix.Comment: 10 pages, 0 figure
Relation between increased transmision in XAS and increase in Abrikosov Vortices as T→Tc
The increased transmission, observed in the EXAFS region of their X-ray absorption spectra, as cuprate materials go through the superconducting transition temperature Tc is correlated with a critical increase in Abrikosov Vortex expulsion in zero magnetic field as the temperature T →Tc
Superconductivity at Т≈200 K in Bismuth Cuprates Synthesized Using Solar Energy
When investigating low-frequency (0.1 Hz) oscillations of multiphase high-temperature cuprate superconductors (HTCS) Bi1,7Pb0,3Sr2Ca(n-1)CunOy (n=2-30), a wide attenuation peak (ΔT~100 К) with a maximum at Т≈200 К was detected. This peak was particularly pronounced in field cooling (FC) experiments, i.e. after abrupt cooling of the sample in the external magnetic field at the temperature Т\u3cТс with subsequent slow warming up to room temperature with invariance of the applied field. The attenuation peak height depended on the preliminaryorientation (before cooling) of the samples θ in the measured permanent magnetic field Н. On the one hand, it is well known that, after the FC procedure and subsequent slow warming up, at the temperatures close to the critical temperature Тс, the attenuation peak associated with “melting” of the Abrikosov frozen vortex structure and its disappearance at Т \u3eТс is detected in monophase samples. At the same time, in most multiphase bismuth HTCS samples, synthesized using solar energy and superfast quenching of the melt, the attenuation peak with the maximum at Т≈200 К was observed.Depending on the conditions of synthesis, the attenuation peak could be two-humped and could be located in the temperature range much wider than Тс of the major superconducting phase. We assume that this is due to the existence of frozen magnetic fluxes (after FC) in superconducting “dropping” regions, which gradually (with increasing temperature) transfer into the normal state and release pinned vortex threads. This fact could be a cause of observed dissipative processes, so as also the evidence of the existence of superconductivity at Т ≥240 К