Multiferroic and thermal expansion properties of metal-organic frameworks

Abstract

As a prototype of organic–inorganic hybrid compounds, metal-organic frameworks (MOFs) have attracted enormous interest for their diverse physical and chemical properties. Recently, the magnetic and electric properties of MOFs have started to draw much attention. In particular, the coexistence of multiple orders (magnetic, electric, and elastic) in some MOFs makes them as emerging multiferroic materials. In terms of the strong and tunable ferroelectricity, the long-distance superexchange interaction, the order–disorder transition of hydrogen bonds in combination with the structural flexibility, and multiferroic MOFs represent a unique family beyond conventional inorganic multiferroics. This perspective provides a brief overview of recent progress in the field of multiferroic MOFs. First, the multiferroic MOFs reported so far are summarized and classified. Then, various cross coupling effects, i.e., the magnetic field control of electric polarization, electric field manipulation of magnetization, and pressure tuning of magnetic and electric properties, are described and discussed. In addition, a number of unusual phenomena such as the giant thermal expansion and quantum effects are introduced. Finally, some promising topics that have not yet been fully explored in multiferroic MOFs are proposed.