Cooling Field Dependence of Exchange Bias in Mn-Doped Metal- Organic Framework [NH2(CH3)2][FeIIIFeII(HCOO)6]
Tianyu Liu1, Yuan Yuan1, Xiaofan Sun1
1National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing210093, People's Republic of China.
Abstract:
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][FeIIIFeII(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 ∼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.
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