Ferroelectricity and Strong Spin–Orbit Coupling to Enhance Molecular Spin-Electric Coupling

The electric control of magnetism has been considered to be promising for molecular spintronics and quantum information. However, the spin-electric coupling strength appears to be insufficient for application in most cases. Two major factors capable of amplifying the relative effect are spin-orbit coupling and ferroelectricity. Herein, we chose four compounds as examples to study the contribution of spin-orbit coupling and ferroelectricity to spin-electric coupling. The relative orientation-dependent Hamiltonian terms were determined via electric-field modulated continuous-wave electron paramagnetic resonance. The origins of the spin-electric coupling effect in the four compounds are discussed and determined according to the characteristics of the experimental spectra. Meanwhile, the results demonstrated that strong spin-orbit coupling is crucial for producing significant spin-electric coupling and that the effect can be amplified by about 2 orders of magnitude by ferroelectricity. This work can guide the rational screen and design of materials with applicable spin-electric coupling strength, which may provoke techniques including low-power spintronics and precise manipulation of the quantum behavior of spins.