Enhanced magnetocaloric effect in manganite nanodisks

Abstract

Manganites are an important class of materials that exhibit a large magnetocaloric effect (MCE). The large MCE is often accompanied by complex magnetic phase transitions associated with electronic phase separation (EPS) in manganites. In previous studies, the effect of EPS on MCE has been examined in chemically synthesized manganite nanoparticles, in which the EPS vanishes when the particle size is smaller than a few tens of nanometers. However, the surface area to volume ratio is high in these small nanoparticles and surface spin disordering can lead to controversial results for MCE measurements. In this study, we used $\mathrm{L}{\mathrm{a}}_{0.425}\mathrm{P}{\mathrm{r}}_{0.2}\mathrm{C}{\mathrm{a}}_{0.375}\mathrm{Mn}{\mathrm{O}}_{3}$ nanodisk arrays fabricated from epitaxially grown thin films as model systems to investigate how MCE changes during a clean transition from the EPS state in thin film and 2-\ensuremath{\mu}m-sized disk arrays to a single ferromagnetic state in 500-nm-sized disk arrays. The MCE of the 500-nm-sized disk array is almost twice that of its parent film. Our results present an approach to improve the MCE in manganite systems for future magnetic refrigeration applications.