The Upper Critical Field, Anisotropy, and Critical Current Density of Superconducting LaO1-xBiS2 with x = 0.07

Abstract

The slice-shaped LaO1-xBiS2 (x = 0.07) superconducting single crystal was grown by a high-temperature flux method. The X-ray diffraction analysis and symmetric M(H) curves along the H-axis indicate no any other impurities are involved in current LaO1-xBiS2 sample. The M(T) curves show the suppression of the Tconset and Tirr with increasing magnetic field applied parallel to the c-axis which is more noteworthy than that under magnetic field perpendicular to the c-axis. The Hc2(T) curves show upward curvature near Tc, which cannot be described by the one-gap model, and similar Hc2(T) curves are observed in REO1-xFxBiS2 and captured by the two-gap model, suggesting LaO1-xBiS2 may be a two-gap superconductor. The superconducting anisotropy parameter (2.8~5.58) of LaO1-xBiS2 (x = 0.07) is estimated by different methods. The structural distortion plays an important role in the smaller superconducting anisotropy parameter of LaO1-xBiS2. The critical current density in the self-field is about 5.9 × 103 Acm−2 and 6.7 × 103 Acm−2 for H//c and H⊥c, respectively.