Magnetoelectric coupling in molecules*

Materials with magnetoelectric (ME) coupling exhibit behavior wherein applied electric field controls the magnetization or applied magnetic field controls the electric polarization. These have many potential and realized applications including electric control of spin qubits or coupling between qubits in molecular magnets. Molecular magnets are particularly promising materials to search for novel ME behavior because of their soft lattices, which can result in exceptionally high coupling constants – deformations on the order of 1% are common. This talk will cover a few of our recent examples: one involves a spin crossover with a valence tautomerization transition where the change in Co spin state causes an electron to migrate across the molecule and toggle the existence of an electric dipole. Another involves the evolution of a frustrated configuration of antiferromagnetic moments that couple to electric polarization via magnetostriction. We will discuss the quantum magnetism of each compound and its symmetry, the evolution of the magnetic states with temperature and magnetic field, and finally the mechanism to couple to electric polarization and dielectric constant. We will discuss measurements of magnetic and electrical properties at low and high magnetic fields, and theoretical calculations.