Magnetic transitions in metal-organic frameworks of [(CH3)2NH2]FeII(HCOO)3, [(CH3)2NH2]CoII(HCOO)3 and [(CH3)2NH2]FeIIIFeII(HCOO)6

Abstract In this work, we report the magnetic properties of metal–organic frameworks (MOF) of perovskite-like [(CH3)2NH2]M(HCOO)3 (M = FeII, CoII) and niccolite-like [(CH3)2NH2]FeIIIFeII(HCOO)6 synthesized by a solvothermal route. The [(CH3)2NH2]FeII(HCOO)3 exhibits two magnetic transitions at the temperatures of ~19 K for the canted weak ferromagnetic ordering and of ~10 K for the blocking of single-ion quantum magnet due to phase separation, while the [(CH3)2NH2]CoII(HCOO)3 shows one magnetic transition at the Curie temperature (TC) of 14.9 K for the canted weak ferromagnetic ordering. Below the TC values, spin-flop transition is observed in the magnetization curves of the [(CH3)2NH2]M(HCOO)3 crystals with the critical magnetic field of about 104 kOe and 90 kOe at 10 K, respectively. Multistep-like jumping magnetization transitions induced by high magnetic field are observed in the [(CH3)2NH2]FeIIIFeII(HCOO)6 in a temperature range between 10 and 25 K, indicating a complex spin configuration different from that in the [(CH3)2NH2]M(HCOO)3 MOFs.