We have investigated the critical current density (JC) properties in magnetic fields under high pressure by pressurizing FeTeXSe1-X bulk single crystals up to 1.3 GPa. This material has the simplest structure among Fe-based superconductors, and the pressure dependence of critical temperature (TC) is remarkable. As a sample preparation method, we used a melting method with two-step heat treatment to produce high-quality FeTeXSe1-X bulk single crystals. We prepared samples with different composition ratios (X=0.55, 0.6, and 0.65) and checked the change of JC for each sample using a high-pressure cell. X=0.6 sample showed that JC was improved by a factor of about 2 with a pressure of 0.24 GPa under 4.2K and 4T. By clarifying the difference in pressure properties depending on the composition ratio, we discuss the flux pinning mechanism of FeTeXSe1-X bulk single crystals.
Keywords: Fe-based superconductor, critical current density, flux pinning, high pressure, composition ratios