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

Abstract

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 InTe1-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 InTe1-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 InTe0.9Se0.1. Such an anomalous behavior has not been observed previously 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 Dew-Hughes model. Finally, combining the results of resistivity and magnetization measurements, the vortex phase diagrams are constructed and discussed.