Unveiling the Structural, Electronic and Magnetic Properties of GdASiO (A = K, Na, and Li) Oxides With Promising Potential for Low-Temperature Magnetic Cooling.

The growing demand for solid-state magnetic cooling, leveraging the magnetocaloric effect requires the discovery of high-performing magnetocaloric materials (MCMs). Herein, a family of Gd-containing MCMs is provided, specifically the GdASiO (A = K, Na, and Li) oxides, which demonstratse exceptional low-temperature magnetocaloric performance. Through comprehensive experimental investigations and theoretical calculations on their structural, electronic, and magnetic properties, it is unequivocally confirmed that all of them crystallize in a hexagonal apatite-type structure (space group P6/m), exhibiting an antiferromagnetic semiconductor ground state with magnetic ordering temperatures below 1.8 K (typically ≈0.7 K for GdKSiO). Furthermore, their remarkable maximum magnetic entropy change (-ΔS ) values of 31.85 and 58.22 J kgK for GdKSiO; 25.31 and 55.01 J kgK for GdNaSiO; and 25.15 and 55.77 J kgK for GdLiSiO, under the magnetic field changes of 0-2 and 0-5 T, respectively, surpass those of prominent low-temperature MCMs, including the commercialized GdGaO (≈14.6 and 32.8 J kgK) paramagnetic salt. These findings in addition to their high environmental stability position these GdASiO oxides as exceptionally promising for practical magnetic cooling applications.