Magnetic proximity effect at the molecular scale: First-principles calculations

We report first-principles analysis of equilibrium and nonequilibrium quantum transport in a Langmuir-Blodgett (LB) film contacted by Fe electrodes. For several LB molecules with different lengths, transport is in the tunneling regime. We found that spin-polarized transport is closely related to a magnetic proximity effect that causes the LB film to develop small but finite magnetic character that determines spin-polarized current and produces unusual tunnel magnetoresistance (TMR) ratio versus bias voltage. This unusual TMR was observed experimentally.