Detailed magnetization study of superconducting properties of YBCO ceramic spheres

Abstract

We present a magnetization study of low density YBCO ceramics carried out in magnetic fields 0.5 Oe < H < 50 kOe. It was demonstrated that superconducting links between grains may be completely suppressed either by a magnetic field of the order of 100 Oe (at low temperatures) or by an increase of temperature above 70 K. This property of present samples allowed to evaluate the ratio between an average grain size and the magnetic field penetration depth lambda. Furthermore, at temperatures T > 85 K, using low-field magnetization measurements, we could evaluate the temperature dependence of lambda, which turned out to be very close to predictions of the conventional Ginzburg-Landau theory. Although present samples consisted of randomly oriented grains, specifics of magnetization measurements allowed for evaluation of lambda_ab(T). Good agreement between our estimation of the grain size with the real sample structure provides evidence for the validity of this analysis of magnetization data. Measurements of equilibrium magnetization in high magnetic fields were used for evaluation of Hc2(T). At temperatures close to T_c, the Hc2(T) dependence turned out to be linear in agreement with the Ginzburg-Landau theory. The value of temperature, at which Hc2 vanishes, coincides with the superconducting critical temperature evaluated from low-field measurements.

arXiv comment10 pages, 12 figures

References in corpus (11)

• Direct observation of the oxygen isotope effect on the in-plane magnetic field penetration depth in optimally doped YBa${}_2$Cu${}_3$O${}_{7-\delta }$
• Systematic behaviour of the in-plane penetration depth in d-wave cuprates
• Pressure effects on the transition temperature and the magnetic field penetration depth in the pyrochlore superconductor RbOs_2O_6
• Anomalous electron-phonon coupling probed on the surface of ZrB${}_{12}$ superconductor
• Systematics of two-component superconductivity in $YB{a}_{2}C{u}_3{O}_{6.95}$ from microwave measurements of high quality single crystals
• Temperature dependence of the upper critical field of type-II superconductors from isothermal magnetization data. Application to high temperature superconductors
• Pressure induced softening of YB_6: pressure effect on the Ginzburg-Landau parameter κ=λ/ξ
• Temperature dependence of the upper critical field of high-Tc superconductors from isothermal magnetization data. Application to polycrystalline samples and ceramics
• Study of pressure effect on the magnetic penetration depth in MgB${}_2$
• On the interpretation of the equilibrium magnetization in the mixed state of high-Tc superconductors
• Two types of Hc2(T) dependences in Bi_2Sr_2Ca_(1-x)Y_xCu_2O_(8+delta) with different Yttrium content

Cited by in corpus (3)

• Larger grains in high-Tc superconductors synthesized by the solid-state reaction route
• Superconducting phase formation in random neck syntheses: a study of the Y-Ba-Cu-O system by magneto-optics and magnetometry
• Comparison of the scaling analysis of the mixed-state magnetization data with direct measurements of the upper critical field in Y-123