Molecular magnetoresistance enhanced by destructive quantum interference of a [π⋯π] supramolecule.

Molecular magnetoresistance shows promise for future computer memory and storage technology applications. In this study, we design a novel molecular device to achieve this magnetoresistance, where a [π⋯π] supramolecule composed of two DCV4T (dicyanovinyl end-capped quaterthiophene) monomers is employed as the functional unit, and sandwiched between two ferromagnetic electrodes. Density functional theory investigations reveal that the magnetoresistance ratio (MR) is influenced by the configuration of the supramolecule and the temperature. Remarkably, the maximum MR of the designed device can reach up to 18 000% even at room temperature. This exceptional magnetoresistance is basically associated with the destructive quantum interference (DQI) between electron transmissions through the highest-occupied and lowest-unoccupied molecular orbitals of the [π⋯π] supramolecule, occurring near the Fermi level of the device. Our study paves the way for significant enhancement of molecular magnetoresistance grounded in the DQI effect, especially through the use of [π⋯π] supramolecules.