Influence of high-pressure heat treatment on magnetocaloric effects and phase transition critical behavior in La0.75Sr0.25Mn0.9Co0.1O3
摘要
The phase transition critical behavior and magnetocaloric effects of La0.75Sr0.25Mn0.9Co0.1O3 compounds synthesized under ambient pressure and a high pressure of 6 GPa were investigated by experiments combined with first-principle calculations. Lattice distortion was enhanced by high-pressure heat treatment. The samples exhibited maximum magnetic entropy changes of 4.96 and 3.95 J·kg−1·K−1, along with relative cooling powers of 365.50 and 403.92 J·kg−1 (at a magnetic field of 7 T). Furthermore, the application of pressure adjusted the Curie temperature near to room temperature. Both samples demonstrated second-order phase transitions, as evidenced by the Arrott curve, and their critical behaviors conformed well to the 3D-Heisenberg model. The density of states and spin density indicate that the magnetization of the compounds mainly originated from the Mn and Co moments.