Strong Magnetocaloric Coupling in Oxyorthosilicate with Dense Gd 3+ Spins.

Searching for working refrigerant materials is the key element in the design of magnetic cooling devices. Herein, we report on the thermodynamic and magnetocaloric parameters of an X ₁ phase oxyorthosilicate, Gd ₂ SiO ₅ , by field-dependent static magnetization and specific heat measurements. An overall correlation strength of | J | S ² ≈ 3.4 K is derived via the mean-field estimate, with antiferromagnetic correlations between the ferromagnetically coupled Gd-Gd layers. The magnetic entropy change -Δ S _m is quite impressive, reaches 0.40 J K ^-1 cm ^-3 (58.5 J K ^-1 kg ^-1 ) at T = 2.7 K, with the largest adiabatic temperature change T _ad = 23.2 K for a field change of 8.9 T. At T = 20 K, the lattice entropy S _L is small enough compared to the magnetic entropy S _m , S _m / S _L = 21.3, which warrants its potential in 2 -20 K cryocoolers with both the Stirling and Carnot cycles. Though with relatively large exchange interactions, the layered A-type spin arrangement ultimately enhances the magnetocaloric coupling, raising the possibilities of designing magnetic refrigerants with a high ratio of cooling capacity to volume.