A molecular crystal shows multiple correlated magnetic and ferroelectric switchings

Simultaneous control of the magnetic and electric properties of materials is crucial for their application in next-generation memory and sensor devices. Herein, we report a single-crystal Co(II) complex that exhibits unprecedented two-step magnetic switching accompanied by paraelectric-ferroelectric-paraelectric phase transition. The ferroelectricity of the material is governed by changes in the directionality of the sulfate dianions therein that trigger nonpolar-polar-nonpolar variation of the crystal symmetry and induce slight structural changes in the Co(II) complex. The unquenched orbital angular momentum of the Co(II) ion, which has trigonal antiprismatic coordination geometry, is susceptible to the coordination environment. Accordingly, two-step magnetic switching accompanied by ferroelectric phase transitions is demonstrated, and the detailed mechanism of the paraelectric-ferroelectric-paraelectric phase transitions and the consequent magnetic switching are investigated. Thus, this study presents a unique multifunctional material as well as a viable strategy for the development of superior molecular magnetoelectric materials.