Effect on the cryogenic magnetocaloric performance through tuning magnetism in Shastry-Sutherland compounds Eu₂Mg_1-xMn_xSi₂O₇ (0 ≤ x ≤ 0.5)

A detailed study of the optimization of the magnetocaloric effect (MCE) of Eu₂MgSi₂O₇ and Eu₂MnSi₂O₇ through tuning the magnetism is conducted. The MCEs of Eu₂Mg_1-xMn_xSi₂O₇ (0 ≤ x ≤ 0.5) compounds are compared with those of unsubstituted Eu₂MgSi₂O₇ and Eu₂MnSi₂O₇. The magnetic ground state of Eu₂MgSi₂O₇ is tuned to ferrimagnetic (FIM) ground state by partial substitution of Mn²⁺ ions for Mg²⁺ ions, which produces a significant effect on the MCE. Doping with Mn²⁺ ions eliminates the inverse MCE and the field-induced first-order magnetic phase transition (MPT) observed in Eu₂MgSi₂O₇ compound. The Eu₂Mg_1-xMn_xSi₂O₇ (0 ≤ x ≤ 0.5) compounds exhibit second-order MPT properties, avoiding the magnetic and thermal hysteresis of first-order MPT materials. Furthermore, the maximum magnetic entropy change (-ΔSmax M) of the Eu₂Mg_1-xMn_xSi₂O₇ (0 ≤ x ≤ 0.5) compounds exceeds the theoretical magnetic entropy limit of the Eu₂MnSi₂O₇ compound. The -ΔSmax M value of the x = 0.125 sample up to 28.7 J kg⁻¹ K⁻¹ at 1.3 K under the magnetic field change μ₀ΔH = 0–2 T, exhibiting excellent low-field MCE that make it a potential application. The present study optimizes the MCEs of Eu₂MgSi₂O₇ and Eu₂MnSi₂O₇ by tuning the magnetism, offering a method to enhance the magnetocaloric performance of Shastry-Sutherland compounds.