Novel gadolinium garnet Gd3Te2Li3O12: magnetism and magnetocaloric performance for sub-kelvin cryogenic applications†

The global helium shortage and escalating costs in cryogenic engineering have intensified demands for helium-free refrigeration technologies. Adiabatic demagnetization refrigeration (ADR) based on the magnetocaloric effect (MCE) presents a viable solution, with its efficacy fundamentally dependent on advanced magnetocaloric materials. Here we present the successful synthesis of a novel gadolinium garnet Gd₃Te₂Li₃O₁₂ through solid-state reaction, which crystallizes in the cubic Iad space group. The integration of magnetic characterization results with density functional theory (DFT) calculations establishes Gd₃Te₂Li₃O₁₂ as an antiferromagnetic compound exhibiting ultra-low magnetic ordering below 0.4 K. A comprehensive evaluation of the sub-kelvin magnetocaloric parameters demonstrates advantageous characteristics compared to commercial gadolinium gallium garnet (GGG) benchmarks, featuring both reduced magnetic ordering temperature and optimized entropy variation in the sub-Kelvin regime. These metrics position Gd₃Te₂Li₃O₁₂ as a prime candidate for sub-Kelvin ADR systems, while the observed geometrically frustrated magnetic sublattice configuration suggests new design principles for next generation magnetocaloric materials.