Close-to-room-temperature magnetoelectric coupling in a molecule-based material

Spin crossovers (SCOs) provide an attractive route to creating switchable materials properties. The spin state can be switched by magnetic and electric fields, light and pressure, and can in turn influence the electrical, optical and structural properties of a material. In the case of molecule-based SCO materials, strong distortion of the lattice accompanying the SCO can give rise to the appearance of electric dipoles that can couple to the magnetic field. Such achieved magnetoelectric coupling has been reported by now in several SCO systems with operating temperatures of 48–200 K and 333–338 K. Current efforts are focused on identifying materials with the coupling appearing at room temperature (RT) which would make them attractive for technological applications such as low power, tunable frequency devices, magnetic sensors, energy harvesting, computing, and data storage. Here we present an example of a polar Fe(II) material which close-to-RT SCO can be induced not only by temperature but also by a magnetic field as low as 5 T. Moreover, we found that changes in electrical properties (dielectric constant and electric polarization) related to the SCO can be induced also by applying low magnetic field near the SCO temperature.