Critical Current Density, Vortex Pinning, and Phase Diagram in the NaCl-Type Superconductors InTe_1–xSe_x (x = 0, 0.1, 0.2)

Research of vortex properties in type-II superconductors is of great importance for potential applications and fundamental physics. Here, we present a comprehensive study of the critical current density J_c, vortex pinning, and phase diagram of NaCl-type InTe_{1 – x}Se_x (x = 0, 0.1, 0.2) superconductors synthesized by high-pressure technique. Our studies reveal that the values of J_c calculated by the Bean model exceed 10⁴ A/cm² in the InTe_{1 – x}Se_x system, signifying good potential for applications. The magnetic hysteresis loops (MHLs) show an asymmetric characteristic at various degrees, which is associated with the surface barrier. Intriguingly, a rare phenomenon in which the second magnetization peak in the MHLs occurs only in the field-descending branch is detected in InTe_0.9Se_0.1. Such an anomalous behavior has not been observed before and can be described by considering the respective roles of the surface barrier and bulk pinning in the field-ascending and field-descending branches. By analyzing the pinning force density versus reduced field, the pinning mechanisms are studied in detail in the framework of the Dew-Hughes model. Finally, combining the results of resistivity and magnetization measurements, the vortex phase diagrams are constructed and discussed.