摘要
Magnetic refrigeration, resulting from the magnetocaloric effect of a material around the magnetic phase-transition temperature, is a topic of great interest as it is considered to be an alternate energy solution to conventional vapor-compression refrigeration. The viability of a magnetic refrigeration system for magnetic cooling can be tested by exploiting materials in various forms, from bulk to nanostrucutres. In this study, magnetocaloric properties of self-assembled Mn 3 O 4 -La 0.7 Sr 0.3 MnO 3 nanocomposites, with varying doping concentrations of Mn 3 O 4 in the form of nanocrystals embedded in the La 0.7 Sr 0.3 MnO 3 matrix, are investigated. The temperatures corresponding to the paramagnetic-to-ferromagnetic transitions are higher, and the values of change in magnetic entropy under a magnetic field of 2 T show an enhancement (highest being ∼130%) for the nanocomposites with low doping concentrations of Mn 3 O 4 , compared to that of pure La 0.7 Sr 0.3 MnO 3 thin films. Relative cooling power remain close to those of La 0.7 Sr 0.3 MnO 3 . The enhanced magnetic phase-transition temperature and magnetocaloric effect are interpreted and evidenced in the framework of interfacial coupling between Mn 3 O 4 and La 0.7 Sr 0.3 MnO 3 . This work demonstrates the potentiality of self-assembled nanostructures for magnetic cooling near room temperature under low magnetic fields.