Critical current density and vortex phase diagram in the superconductor Sn0.55In0.45Te

Critical current density and vortex pinning dynamics have been studied in the superconductor Sn0.55In0.45Te. Analysis of the temperature-dependent lower critical field shows that it has a weakly anisotropic single energy gap. The critical current density Jc(0) and pinning potential U0(H) values reach as high as 2.56??103 A/cm2 at 1.8 K and 2.1??103 K at ??0H = 0.01 T, respectively. Based on the collective pinning model, we demonstrate the coexistence of vortex pinning regimes in Sn0.55In0.45Te. One is a ??Tc pinning regime induced by the spatial fluctuations of the transition temperature in a low field. The other is a dominantly ??l pinning regime associated with the spatial variations of the charge-carrier mean free path in a higher field. This causes a nonconstant exponent of the power-law behavior Jc(T ) ??? Hn. A very weak vortex fluctuation is unveiled by a narrow separation between the irreversibility field ??0Hirr(T ) and upper critical field ??0Hc2(T ) in the vortex phase diagram. We discuss the potential application in superconducting electronics like the single-photon detector in thin film form.