The Observed Topological Vortex Domains and the Rotating Magnetocaloric Effect in the Hexagonal RMnO (R = Ho, Er, and Yb) Crystals

Hexagonal RMnO (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 -Mn interactions and anisotropic properties were observed in the RMnO crystals. The broad peaks of magnetic entropy change -ΔS appeared around [Formula: see text] revealed that the order of R moments is crucial to the large MCE. A giant rotating MCE (RMCE: ∼10.57 J kg K) was obtained with magnetic field changing from 0 to 50 kOe in ErMnO, accompanied with a large refrigerant capacity (RC: ∼159 J kg). These significant RMCE and RC behaviors are found to be closely related to the R -R , and R -Mn interactions in these RMnO. These results may open up a possibility for designing low-temperature magnetic cooling devices by tailoring the R-4f and Mn-3d orbit interactions.