La0.6X0.1Te0.3MnO3 system with significant refrigerant capacity at low magnetic field and double magnetic entropy change peaks: effect of ball-milling time on physical and critical behaviors

Abstract

We have investigated the ball-milling time effect on different physical properties of La0.6X0.1Te0.3MnO3 (X is a lacuna) system (LT) milled for 1 h (LT-1h), 3 h (LT-3h), and 6 h (LT-6h). According to Williamson-Hall method, as the ball-milling duration is increased, the material’s crystallite size decreases from approximately 145 to 99 nm for LT-1h and LT-6h, respectively. Electronic study was also investigated. The Zero-Field-Cooling and Field-Cooling (ZFC/FC) magnetization measurements illustrated that all the systems are presenting a ferromagnetic to paramagnetic phase transition around Curie temperature (TC). This transition is around 176, 182, and 183 K accompanied by a decrease in the magnitude in both ZFC and FC data. Thus, increasing the ball-milling time of the sample leads to the elevation of TC and does not enhance the magnitude of the magnetization the fact that it affects the magnetic interactions between atoms. By increasing the ball-milling duration, the proportion of homogeneity is increased, and the material becomes slightly more resilient, according to the Curie-Weiss law. Additionally, it is accompanied with an increase in coercivity and a decrease in the saturation magnetization and remanence. Based on the AC-susceptibility, raising the ball-milling time facilitates the appearance of a spin-glass (SG) state. The relative cooling power (RCP) value in the LT-1h sample at 2 T is 108% (211.758 J kg−1) compared to that of the Gd at 2 T. Consequently, the LT sample could be a permanent magnet in a magnetic refrigerator. Noting that raising the ball-milling time weakens the RCP. Both LT-1h and LT-3h systems are belonging to the tricritical mean field model. However, for LT-6h, the model changed and the best one became the 3D-Ising model. Hence, the ball-milling time influences also the universality class.