The observed topological vortex domains and the rotating magnetocaloric effect in the hexagonal RMnO3 (R = Ho, Er, and Yb) crystals

Abstract

Abstract Hexagonal RMnO3 (R = Er, Ho and Yb) single crystals were grown and their unique vortex domain structures, magnetic properties and magnetocaloric effect (MCE) were comprehensively investigated. The topological vortex domains/structures were clearly illustrated by polarized optical microscope and piezo response force microscopy, confirming a high quality of the crystals. The magnetic transitions related to R 3+–Mn3+ interactions and anisotropic properties were observed in the RMnO3 crystals. The broad peaks of magnetic entropy change −ΔS M appeared around T N R revealed that the order of R 3+ moments is crucial to the large MCE. A giant rotating MCE (RMCE: ∼10.57 J kg−1 K−1) was obtained with magnetic field changing from 0 to 50 kOe in ErMnO3, accompanied with a large refrigerant capacity (RC: ∼159 J kg−1). These significant RMCE and RC behaviors are found to be closely related to the R 3+–R 3+, and R 3+–Mn3+ interactions in these RMnO3. These results may open up a possibility for designing low-temperature magnetic cooling devices by tailoring the R–4f and Mn–3d orbit interactions.