Enhanced Magnetocaloric Effect Driven by Interfacial Magnetic Coupling in Self-Assembled Mn3O4–La0.7Sr0.3MnO3 Nanocomposites
2015
Vandrangi, Suresh K. | Yang, Jan-Chi | Zhu, Yuan-Min | Chin, Yi-Ying | Lin, Hong-Ji | Chen, Chien-Te | Zhan, Qian | He, Qing | Chen, Yi-Chun | Chu, Ying-Hao
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 Mn₃O₄–La₀.₇Sr₀.₃MnO₃ nanocomposites, with varying doping concentrations of Mn₃O₄ in the form of nanocrystals embedded in the La₀.₇Sr₀.₃MnO₃ 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 Mn₃O₄, compared to that of pure La₀.₇Sr₀.₃MnO₃ thin films. Relative cooling power remain close to those of La₀.₇Sr₀.₃MnO₃. The enhanced magnetic phase-transition temperature and magnetocaloric effect are interpreted and evidenced in the framework of interfacial coupling between Mn₃O₄ and La₀.₇Sr₀.₃MnO₃. This work demonstrates the potentiality of self-assembled nanostructures for magnetic cooling near room temperature under low magnetic fields.
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