Organic spin valves with inelastic tunneling characteristics

Abstract

Electrons may experience inelastic coupling with the organic spacer layer during tunneling between two ferromagnetic electrodes. To probe the transport behavior of spin-polarized electrons in organic materials, organic spin valves were fabricated utilizing a relatively thin organic barrier of 3,4,9,10-perylene-teracarboxylic dianhydride (PTCDA) dusted with alumina at the organic/ferromagnetic interfaces. These structures, with an organic barrier layer, exhibited magnetoresistance up to 12% at room temperature. In studies of the inelastic tunneling spectrum, the observed characteristic peak of the organic layer provides direct evidence of the interplay between the spin-polarized electrons and the organic molecules. Combining the inelastic tunneling results with a simple molecular vibration calculation yields further information on the configuration of the molecular thin film and the possible tunneling states of the spin-polarized electrons. Such interplay indicates a true transport of spin-polarized electrons through organic material rather than through defects or interdiffusion compounds formed at the interfaces within the organic spin valve.