New magnetic, electric and anisotropic features of ammonium nickel formate revealed
New magnetic, electric and anisotropic features of ammonium nickel formate revealed lead image
Combining dense, inorganic metal coordination layers with organic interlayers can form hybrid layered perovskite crystals with wide ranges of new physical properties like antiferromagnetism and ferroelectricity. The open interlayer space allows the use of various organic moieties to form multiferroics, such as layering metal-halides with organic ammonium cations.
Few layered ammonium metal formates currently exist, and relatively little is known about their properties. A newly developed hybrid 2-D material — ammonium nickel formate [NH4Cl]2[Ni(HCOO)2(NH3)2] — looks to provide a better understanding of these potentially multiferroic materials. Chen et al. characterized the newly created hybrid layered perovskite compound in a detailed, temperature- and direction-dependent physical analysis that explored the material’s magnetic, electric and anisotropic features.
The two-dimensional material displays both electric and magnetic orderings, which makes it particularly interesting to the multiferroics research community. The authors found that it exhibits transitions from paramagnetic to antiferromagnetic states, and strong anisotropic dielectric responses related to 90-degree turns in electric and magnetic polarization.
The layered ammonium nickel formate also undergoes a ferroelectric transition at about 110 kelvins from a high-temperature, high-polarized phase to a low-temperature, low-polarized phase via an intermediate incommensurate phase. Then, at 25 kelvins, the material undergoes a paramagnetic to antiferromagnetic transition, and both electric and magnetic polarizations turn from the direction perpendicular to the layers to the parallel direction during the transitions.
The authors indicate that the findings demonstrate new possibilities to combine layered perovskite metal-formates with various interlayer inorganic and organic components. The next steps are to study the intermediate incommensurate structure, paving the way for other layered metal-formate systems.
Source: “Electric and magnetic transitions with 90° turning of polarizations in a layered perovskite of [NH4Cl]2[Ni(HCOO)2(NH3)2],” by Sa Chen, Ran Shang, Bing-Wu Wang, Zhe-Ming Wang, and Song Gao, APL Materials (2018). The article can be accessed at https://doi.org/10.1063/1.5040688 .
