Gadolinium oxyorthogermanate Gd2GeO5: An efficient solid refrigerant material for magnetic cryocoolers

Abstract

We report here the magnetic interactions, magnetocaloric effect and thermodynamic parameters of an efficient magnetic refrigerant material, Gd2GeO5, through magnetization and heat capacity measurements, as well as a mean-field and scaling analysis approach. An isotropic antiferromagnetic exchange coupling with energy scale εex = JexS2 ≈ 2.6 K is estimated from analysing the magnetization dependences, in agreement with the couplings derived from the density functional theory (DFT). The Gd2GeO5 shows an exceptionally large isothermal magnetic entropy change of 0.36 J K−1 cm−3 (50.3 J K−1 kg−1) and relative cooling power of 4.34 J cm−3 (611.3 J kg−1) for a field change of 8.9 T, with the highest adiabatic temperature change being 22.2 K, which is quite impressive for use in helium-free magnetic cryocoolers.