Multiferroicity and magnetoelectric coupling in the paramagnetic state of the metal-organic framework [(CH3)2NH2] Ni(HCOO)3

The metal-organic framework [(CH3)(2)NH2]Ni(HCOO)(3) (DMA-Ni) has an ABX(3) perovskite-like structure. At T-C similar to 181 K, DMA-Ni displays a first-order ferroelectric transition, which is triggered by the disorder-order transition of hydrogen bonds. In addition, this compound exhibits a spin-canted antiferromagnetic order below T-N similar to 37.6 K through the long-distance superexchange interaction, and a spin-reorientation transition appears near 15 K. The coexistence of magnetic and ferroelectric orders at low temperature testifies the multiferroic properties of DMA-Ni. Besides, the magnetoelectric (ME) coupling exists in the paramagnetic state, where the ferroelectric polarization can be modified by applying high magnetic fields. This behavior is attributed to the local magnetostriction effect.