Reversible magnetic properties of c-axis-oriented superconducting ${\mathrm{Bi}}_2$${\mathrm{Sr}}_2$${\mathrm{Ca}}_2$${\mathrm{Cu}}_3$${\mathrm{O}}_{10}$

Magnetization measurements on c-axis-oriented bulk superconducting ${\mathrm{Bi}}_2$ ${\mathrm{Sr}}_2$ ${\mathrm{Ca}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_{10}$ have been carried out with the magnetic field applied parallel to the c axis. Fitting the results to the variation model for magnetization suggested by Hao and Clem shows that the Ginzburg-Landau parameter κ is nearly constant for 74≤T≤86 K, with the value of 170 at 74 K, and slowly increases with temperature from ∼86 to ∼100 K. κ diverges in the vicinity of ${\mathit{T}}_{\mathit{c}}$. This unusual temperature dependence of κ(T) could come from extended fluctuation effects and a limitation of the Hao-Clem theory, which may fail to describe this extremely anisotropic Bi-based superconductor. By fitting the data with the value of κ equal to 170, the deduced values of some of the superconducting parameters are ${\mathit{H}}_{\mathit{c}}$(0)=10 600 Oe, ξ(0${)}_{\mathit{a}\mathit{b}}$=10.5±0.6 Å, λ(0${)}_{\mathit{a}\mathit{b}}$=1940±13 Å, ${\mathit{dH}}_{\mathit{c}2}$/dT≃-3.68 T/K near ${\mathit{T}}_{\mathit{c}}$.