Antiferromagnetic ordering and large magnetic entropy in the layered rare-earth oxyhalide DyOX (X=F,Br)

The burgeoning field of rare-earth (RE)-based van der Waals (vdW) layered magnets is driven by their potential in novel magnetism and spintronics applications. These materials exhibit exceptional spin-lattice coupling and air stability, attributed to the strong spin-orbit coupling and substantial magnetic moments from the 4f electrons. This study investigates the structural and magnetic properties of dysprosium-based oxyhalide ternary compounds, DyOX (X=F,Br), which are the prime candidates for multiphase transitions and tunable magnetic anisotropy through halogen substitution at the vdW layer edges. Utilizing complementary neutron diffraction, first-principles calculations, and magnetic measurements, we elucidate the intrinsic properties of these oxyfluoride compounds. DyOF exhibits an antiferromagnetic (AFM) ground state below the Néel temperature (TN) of 3.7 K, with a commensurate propagation vector k = (0, 0, 3/2) and magnetic moments aligned within the ab plane. In contrast, DyOBr has a higher TN=9.9 K and displays more complex magnetic transitions. The large magnetic moment (∼10 µB/Dy), strong magnetic anisotropy, and field-induced metamagnetic transitions observed in DyOX (X=F,Br) magnetic insulators suggest their potential for realizing magnetism in the two-dimensional (2D) limit. The magnetocaloric effects are further investigated to manifest the properties of DyOX (X=F,Br). Notably, DyOF demonstrates a superior magnetic refrigeration capacity, with a maximum magnetic entropy change −ΔSM of 25.3 JK−1kg−1 and a relative cooling power of 530.2 Jkg−1 at 7 T, surpassing most vdW layered magnets. The findings contribute to the understanding of 4f electron-related properties in 2D magnetism and pave the way for emerging applications in antiferromagnetic spintronics and cryomagnetic refrigeration. locked icon locked icon locked icon locked icon locked icon locked icon Physics Subject Headings (PhySH)AntiferromagnetismMagnetic orderMagnetic phase transitionsMagnetic refrigerationRare-earth magnetic materialsMagnetization measurementsNeutron diffraction