Intrinsic pinning property of FeSe0.5Te0.5

The intrinsic pinning properties of FeSe0.5Te0.5, which is the superconductor with Tc of about 14 K, were studied by the analysis of magnetization curves by the extended critical state model. In the magnetization measurements by SQUID magnetometer, the external magnetic fields were applied parallel and perpendicular to c-axis of the sample. The critical current density Jc's under the perpendicular field of 1 T were estimated by using the Kimishima model as about 1.6 x 10^4, 8.8 x 10^3, 4.1 x 10^3, and 1.5 x 10^3 A/cm2 at 5, 7, 9, and 11 K, respectively, and the temperature dependence of Jc could be fitted with the exponential law of Jc(0)xexp(-αT /Tc) up to 9 K and power law of Jc(0)x(1-T / Tc)n near Tc.