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.
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http://dx.doi.org/10.1088/1361-648X/abb680 | DOI Listing |
Nanophotonics
January 2025
Departments of Optics and General Physics, Francisk Skorina Gomel State University, Sovetskaya Str. 104, Gomel 246019, Belarus.
Optical vortex beams carrying orbit angular momentum have attracted significant attention recently. Perfect vortex beams, characterized by their topological charge-independent intensity profile, have important applications in enhancing communication capacity and optimizing particle manipulation. In this paper, metal-insulator-metal copper-coin type reflective metasurfaces are proposed to generate perfect composite vortex beams in X-band.
View Article and Find Full Text PDFNatl Sci Rev
February 2025
State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China.
To achieve logic operations via Majorana braiding, positional control of the Majorana bound states (MBSs) must be established. Here we report the observation of a striped surface charge order coexisting with superconductivity and its interaction with the MBS in the topological superconductor 2M-WS, using low-temperature scanning tunneling microscopy. By applying an out-of-plane magnetic field, we observe that MBSs are absent in vortices in the region with stripe order.
View Article and Find Full Text PDFLight Sci Appl
January 2025
Laboratoire Matériaux et Phénomènes Quantiques, Université Paris Cité and CNRS, Paris, 75013, France.
Vortex beams are currently drawing a great deal of interest, from fundamental research to several promising applications. While their generation in bulky optical devices limits their use in integrated complex systems, metasurfaces have recently proven successful in creating optical vortices, especially in the linear regime. In the nonlinear domain, of strategic importance for the future of classical and quantum information, to date orbital angular momentum has only been created in qualitative ways, without discussing discrepancies between design and experimental results.
View Article and Find Full Text PDFOptical misalignment between transmitter and receiver leads to power loss and mode crosstalk in a mode division multiplexing (MDM) free-space optical (FSO) link. We report both numerical simulations and experimental results on the propagation performance of two typical vector beams, C-point polarization full Poincaré beams (FPB), and V-point polarization cylindrical vector beams (CVB), compared to homogeneous polarization scalar vortex beams (SVB) under optical misalignment. The FSO communication performance under misalignment using different transmit beams is evaluated in terms of power loss, mode crosstalk, power penalty, etc.
View Article and Find Full Text PDFDirac-vortex cavities have single-mode emitting, scalable mode areas, arbitrary mode degeneracies, and vector-beam vertical emission, which attract more and more researchers' attention. Here, we demonstrate the single-mode of two-dimensional transverse magnetic (TM) Dirac-vortex topological cavity modes that are not only generally available for high power topological surface-emitting lasers (TCSEL) but also are one of the excellent candidates for refractive index sensors. The principle for winding number is studied, and the scaling laws are shown with cavity mode diameters.
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