Tailoring the cryogenic magnetism and magnetocaloric effect from Zr substitution in EuTiO3 perovskite.

• Both first-principles calculation and experimental results demonstrate the ferromagnetic feature for EuTi 0.875 Zr 0.125 O 3. • Lattice expansion and changes in electron interaction induced by Zr substitution contribute to the AFM‒FM transition, accompanied by significantly enhanced low-field MCE. • For Δ μ 0 H =0−1 T, the peaks of -Δ S M , RC, and Δ T ad reach 17.9 J kg⁻¹ K⁻¹, 87.4 J kg⁻¹, and 6.1 K, respectively. • Prominent magnetocaloric performance makes EuTi 0.875 Zr 0.125 O 3 compound one of the best magnetic refrigerants in the liquid helium temperature range. Refrigeration in the liquid helium temperature range provides vital technological support for many scientific frontiers and engineering technologies. The considerable magnetocaloric effect (MCE) makes EuTiO 3 a potential candidate for magnetic refrigeration near liquid helium temperature. More interestingly, the magnetic transition from antiferromagnetism to ferromagnetism offers the possibility to tailor the magnetism and improve the MCE of this magnetic system. In this study, the magnetic properties and MCE of EuTi 0.875 Zr 0.125 O 3 were systematically investigated by first-principles calculation and experiments. The substitution of Zr induces a significant lattice expansion and alters the electronic interactions, leading to a dominance of ferromagnetism in the compound. Remarkable low-field MCE performance has been achieved attributed to the enhanced ferromagnetism and low saturation field. Under the field change of 0–1 T, the maximum magnetic entropy change (− Δ S M m a x ) and adiabatic temperature change (Δ T a d m a x ) are 17.9 J kg⁻¹ K⁻¹ and 6.1 K, respectively. It is worth noting that the − Δ S M m a x of EuTi 0.875 Zr 0.125 O 3 reaches 10.3 J kg⁻¹ K⁻¹ for a field change of 0–0.5 T, making it one of the best magnetocaloric materials ever reported operating in the liquid helium temperature range. [Display omitted] [ABSTRACT FROM AUTHOR]