Magneto-electric (M-E) response at the molecular level arises from the interaction of matter with the electric and magnetic fields of light, and can manifest itself as nonlinear M-E magnetization (MNL) or M-E rectification (PNL). However, there is presently a limited understanding of how molecular material properties impact M-E response. Here we investigate the relationship between M-E nonlinear coefficients and the third-order electric susceptibility, χ(3), finding that MNL is proportional to χxxxx(3) while PNL scales with χzzxx(3) due to a cascaded nonlinearity. By applying a sum-over-states (SOS) expression for the elements of χ(3) to valence-bond charge-transfer (VB-CT) models, we formulate practical guidelines for the design of materials expected to exhibit enhanced M-E properties. On this basis, we predict that many conventional nonlinear optical chromophores with large values of χxxxx(3) may be suitable for generating optical magnetism at low intensities. In the case of M-E rectification, analysis of Λ-shaped, X-shaped, and octupolar VB-CT models suggests that their molecular structures can be tuned to enhance the response by maximizing χzzxx(3). In particular, octupolar molecules with a predominantly CT character ground state and Λ-shaped chromophores with weakly conjugated bridges between donor and acceptor moieties should promote off-diagonal nonlinearity and M-E rectification.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films