Anisotropy and reversible magnetization of the infinite-layer superconductor Sr_0.9La_0.1CuO₂

We present reversible magnetization measurements of a c-axis aligned Sr_0.9La_0.1CuO₂ infinite-layer superconductor with T_c≃43K. The magnetization measured as a function of temperature and angle between the c axis and the external magnetic field are analyzed in terms of the Hao-Clem model. Consequently, the critical fields [H_c(0), H_c1^c(0), and H_c2^c(0)] and the characteristic lengths [ξ_ab(0) and λ_ab(0)] are derived. We introduce a novel technique to describe the angular dependence of magnetization using the Hao-Clem model by employing the effective mass anisotropy. The anisotropy ratio γ=9.3 and the zero-temperature coherence length along the c axis ξ_c(0)=5.2Å are obtained by the technique. The coherence length ξ_c(0) is longer than the c-axis lattice parameter c=3.41Å, which implies three-dimensional coupling between CuO₂ planes even at zero temperature.