Microscopic Insights on the Multiferroic Perovskite-Like [CH3 NH3 ][Co(COOH)3 ] Compound.

ABSTRACT

The characterization of the crystal structure, phase transitions, magnetic structure and dielectric properties has been carried out on [CH3 NH3 ][Co(COOH)3 ] (1) perovskite-like metal-organic compound through variable-temperature single-crystal and powder neutron and X-ray diffraction and relative permittivity measurements. The paraelectric to antiferroelectric-like phase transition observed at around 90 K is triggered by a structural phase transition; the structural studies show a change from Pnma space group at RT (1A) to P21 /n space group at low temperature (1B). This phase transition involves the occurrence of small distortions in the framework and counterions. Neutron diffraction studies have shown a magnetic order showing spontaneous magnetization below 15 K, due to the occurrence of a non-collinear antiferromagnetic structure with a weak ferromagnetic component, mainly due to the single-ion anisotropy of the CoII ions.