Weak magnetic interaction, large magnetocaloric effect, and underlying spin model in triangular lattice GdFeTeO6

The nature of 4f-3d magnetic interaction in oxides as well as its influence on the magnetocaloric effect (MCE) is an interesting topic. Here, we report the weak magnetic interaction and large MCE in a new triangular lattice GdFeTeO6 synthesized by the solid state reaction method. The weak exchange, which was seldom observed in 4f-3d oxides, is supported by the low ordering temperature (TC ≤ 3 K) and a positive but small Curie-Weiss temperature (θp = 3 K). Under an external magnetic field, the magnetization process yields a large magnetic entropy change of 38.5 J kg−1 K−1 at 5 K for 0-7 T and 23.6 J kg−1 K−1 at 3 K for 0-3 T. Finally, our first-principles calculations demonstrate a ferrimagnetic spin model with the Gd(↑)-Gd(↑)-Fe(↓)-Fe(↓) configuration. The weak magnetic interaction is an average effect of ferromagnetic (4f-4f and 3d-3d) and antiferromagnetic (4f-3d) interactions. The antiferromagnetic 4f-3d interaction is a reason for the reduction of MCE.The nature of 4f-3d magnetic interaction in oxides as well as its influence on the magnetocaloric effect (MCE) is an interesting topic. Here, we report the weak magnetic interaction and large MCE in a new triangular lattice GdFeTeO6 synthesized by the solid state reaction method. The weak exchange, which was seldom observed in 4f-3d oxides, is supported by the low ordering temperature (TC ≤ 3 K) and a positive but small Curie-Weiss temperature (θp = 3 K). Under an external magnetic field, the magnetization process yields a large magnetic entropy change of 38.5 J kg−1 K−1 at 5 K for 0-7 T and 23.6 J kg−1 K−1 at 3 K for 0-3 T. Finally, our first-principles calculations demonstrate a ferrimagnetic spin model with the Gd(↑)-Gd(↑)-Fe(↓)-Fe(↓) configuration. The weak magnetic interaction is an average effect of ferromagnetic (4f-4f and 3d-3d) and antiferromagnetic (4f-3d) interactions. The antiferromagnetic 4f-3d interaction is a reason for the reduction of MCE.