An unusual magnetic phenomenon in Mg doping [(CH3)2NH2] CoxMg1-x[HCOO]3 frameworks

In this study, Mg doping metal-organic frameworks (MOFs) [(CH3)(2)NH2] Co1-xMgx[HCOO](3) single crystals were synthesized by solvothermal method with normal ratios x = 0, 0.1, 0.2, 0.3, 0.4, 0.6. Powder X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDX) results showed that Mg ion is uniformly doped into Co-based MOFs crystal. With the increase of diamagnetic magnesium ions doping, the antiferromagnetic phase transition temperature of Co-based MOFs for pure Co-MOF decreased from 15K to 7.5K for x = 0.4. Abnormal larger magnetic hysteresis was obtained for Mg doping crystals with a large coercive field 3100 Oe (x = 0.1), 3700 Oe ( x = 0.2), 2900 Oe (x = 0.3) compared with 600 Oe coercive field for pure Co-MOFs (x = 0). At the same time, step-like behavior was first observed on Mg2+ doping sample with x = 0.1-0.3. This unusual magnetic phenomenon is well interpreted based on the coexistence of long-range canted antiferromagnetic order and isolated single-ion quantum magnets. The diamagnetic magnesium ions doping decreases the strong exchange coupling between neighboring Co ions and step-like behavior stemmed from the quantum tunneling of isolated Co ions. Copyright (C) 2022 EPLA

Automated summary

In this study, Mg-doped metal-organic frameworks (MOFs) single crystals were synthesized, and the effects of Mg ion doping on the magnetic properties of MOFs were investigated. The results showed that Mg ion is uniformly doped into the Co-based MOFs crystal, leading to a decrease in the antiferromagnetic phase transition temperature and the emergence of abnormal magnetic hysteresis behavior.