Magnetocaloric effects in the quasi-1D chain carbonate NaDy(CO3)F2 through crystallographic directional rotation

Abstract

Strong quantum fluctuations and weak magnetic interactions in quasi-one-dimensional (1D) chain rare earth (RE) magnets prevent long-range magnetic ordering, preserving magnetic entropy for ultra-low temperature refrigeration. In this study, we investigated the rotating magnetocaloric effect (MCE) of a Dy-based 1D chain carbonate, NaDy(CO₃)F₂, using magnetic susceptibility and specific heat measurements. Millimeter-scale single crystals were successfully grown under supercritical hydrothermal conditions. The temperature-dependent magnetic susceptibility and specific heat measurements marked the onset of long-range magnetic ordering (T_N ∼ 2.4 K) for NaDy(CO₃)F₂. Additionally, its isothermal magnetic entropy change (ΔS_mag) was examined based on millimeter-sized single crystals. Our results reveal a giant, direction-dependent MCE of NaDy(CO₃)F₂, providing an excellent example of achieving significant enhancement of MCE by rotating the crystallographic direction of well-oriented single crystals.