Magnetic and Dielectric Switchings Actuated by the Rotation of the Picoline Ligand in an Iron-Based Dinuclear Phase-Transition Complex

Abstract

Multifunctional materials with switchable magnetic and dielectric properties are crucial for the development of memory and sensor devices. Herein, we report a methoxy-bridged dinuclear iron–pyridyl complex [Fe2(4-picoline)4(NCS)4(μ-OCH3)2] (1), which shows simultaneous thermal-induced magnetic and dielectric switchings. Within the phase-transition temperature range, both magnetic switching and the dielectric anomaly were detected, in which the thermal hysteresis loops were 23 and 21 K, respectively. Detailed structural analyses revealed that these simultaneous switchings were rooted in the flexible rotatable ligands, which were actuated by readjusting the π–π intermolecular interactions between the pyridine ligands in the trans positions of the metal centers. These results were comprehensively investigated both experimentally and theoretically. This study presents a new guideline to control both the magnetic and dielectric properties of molecular complexes by external stimuli.

Hysteretic magnetism–dielectricity switching in 2D Hofmann type spin-crossover compounds

“…The simultaneous magneto-dielectric transition showed a 20 K-wide thermal hysteresis in the same temperature range. A few reported SCO compounds have also shown the consistency between magnetic and dielectric transitions, [43][44][45][46]54,55 whilst a wide thermal hysteresis is not common. This motivated us to further investigate the origin of dielectric anomaly and thermal hysteresis.…”

High-Temperature Metal-Free Molecular Ferroelectrics with Large Spontaneous Polarization

“…Molecular ferroelectrics, which exhibit a spontaneous polarization ( P s ) capable of being switched by an external electric field, have emerged as an exciting research frontier in materials science because of their great potential applications in nonvolatile memories, sensors, actuation, electro-optic devices, and others. − In comparison with the traditional inorganic ferroelectrics, such as BaTiO 3 (BTO) and Pb­(Zr,Ti)­O 3 (PZT), molecular species offer the merits of mechanical flexibility, environmental friendliness, and transparent appearance. In recent years, numerous molecular ferroelectrics with diverse structures have been developed, and several intriguing ferroelectric-related phenomena have been observed, − including ferroelectric switching corresponding to the rotation of molecular rotors, − substantial piezoelectricity, − self-driven broad-spectrum polarized photodetection, , polarization switching associated with chiral inversion, and simultaneous variation of electric ordering and magnetic properties. − For technological applications, a high operational temperature and a large P s are preferred. However, metal-free molecular ferroelectrics that meet these requirements remain rare.…”