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

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 R3+-Mn3+ interactions and anisotropic properties were observed in the RMnO3 crystals. The broad peaks of magnetic entropy change -Delta S-M appeared around TNRR3+ moments is crucial to the large MCE. A giant rotating MCE (RMCE: similar to 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: similar to 159 J kg(-1)). These significant RMCE and RC behaviors are found to be closely related to the R3+-R3+, andR(3+)-Mn(3+)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.