Electric Field Control of Spin-Dependent Dissipative Electron Transfer Dynamics in Mixed-Valence Molecules

We demonstrate that the borderline class II/III magnetic MV dimers, which can be referred to as single molecule multiferroics, provide a unique possibility to achieve electric field control of the electron transfer (ET) dynamics. As an example, we consider a MV dimer d 2-d 1 in which an extra electron is delocalized over two spin-cores (s 0 = 1/2), and the ET is spin-dependent due to the double exchange mechanism. It is assumed that the “extra” electron is coupled to the only intramolecular vibration, and a weak coupling to the dissipative subsystem (thermal bath) is taken into account. The vibronic energy levels and the wave functions of the isolated dimer (quantum part of the system) are numerically evaluated within the vibronic Piepho, Krausz, and Schatz (PKS) model. The dissipative dynamical behavior is treated within the multilevel Redfield approach for the reduced density matrix. The external electric field is assumed to initially stabilize either ferro (S = 3/2)- or antiferromagnetic (S = 1/2) spin state, and then the field is instantly switched off initiating ET dynamics. We evaluate the time evolution of the site occupations for the extra electron as well as the mean values of the electric dipole moment and molecular out-of-phase reaction coordinate. It is demonstrated that the ET dynamics essentially depends on the spin of the initially stabilized state, and we conclude that under certain conditions the dynamical properties of MV compounds can be efficiently controlled by the electric field of attainable strength. This opens also an efficient way to create long-living metastable spin states and inverted populations in MV dimers embedded in solids that seems to be promising for applications in spintronics.