Anisotropic superconductivity of Ca_1−xLa_xFeAs₂(x∼ 0.18) single crystal

Abstract

Anisotropic superconducting properties including the upper critical field\nHc2, thermal activation energy U0, and critical current density Jc are\nsystematically studied in a large Ca1-xLaxFeAs2 single crystal (x ~ 0.18). The\nobtained Hc2 bears a moderate anisotropy gamma of approximately 2-4.2, located\nbetween those of '122' Ba1-xKxFe2As2 (1 < gamma < 2) and '1111' NdFeAsO1-xFx (5\n< gamma < 9.2). Both the magnitude of U0 and its field dependence are very\nsimilar to those of NdFeAsO1-xFx, also indicating anisotropic\nsuperconductivity. Moreover, high and anisotropic Jc's exceeding 10^5 A/cm2\nhave been calculated from the magnetization hysteresis loops, indicating the\nexistence of strong bulk-dominated pinning in the present superconducting\nmaterial.\n