Organic spin valves with inelastic tunneling characteristics

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.