Cooling Field Dependence of Exchange Bias in Mn-Doped Metal- Organic Framework [NH2(CH3)2][FeIIIFeII(HCOO)6]

Herein, an intriguing exchange bias (EB) effect manifesting itself from positive to negative with an increase in the cooling field (HFC) is reported in the single crystal of Mn-doped metal-organic framework (MOF) [NH2(CH3)(2)][(FeFeII)-Fe-III(HCOO)(6)] (1) by finely tuning the exchange interactions between the magnetic ions. Note that the doping ratio of Mn relative to the total metal ions is about 15%. Negative magnetization and EB below the compensation temperature were both observed in 1, and the EB field (HE) changes its sign from positive to negative when HFC is larger than similar to 10 kOe. The abnormal HFC dependence of EB can be interpreted explicitly by a combination of negative magnetization and couplings among the ions of Fe3+, Fe2+, and Mn2+ with varying the HFC. This work demonstrates a tunable EB in MOFs, in favor of designing novel magnetic devices.

Automated summary

In this study, an intriguing exchange bias effect in Mn-doped metal-organic framework is reported, where the bias changes from positive to negative with increasing cooling field. By finely tuning the exchange interactions between magnetic ions, the exchange bias can be controlled, which is beneficial for designing novel magnetic devices.