A heterometallic strategy to achieve a large magnetocaloric effect in polymeric 3d complexes

Abstract

Metal formate frameworks [A][CrMn(HCOO)₆] (A = CH₃NH₂CH₃⁺ for 1 and CH₃NH₃⁺ for 2) with a large MCE were obtained, directed by the heterometallic strategy in which very weak magnetic interactions were achieved. A switch from antiferromagnetism to ferromagnetism occurs when replacing the CH₃NH₂CH₃⁺ cation with CH₃NH₃⁺. The magnetic entropy change (−ΔS_m) reached 48.20 J kg⁻¹ K⁻¹ for 2, which is the largest among the known polymeric 3d complexes.