We have investigated a Coulomb-blockade effect and a higher order cotunneling effect in rubrene-Co nanocomposite spin devices, where the Co nanoparticles were uniformly embedded into the rubrene matrix and a large magnetoresistance (MR) effect appeared. A clear Coulomb gap was observed between ±1.1 V at low temperature. Within the gap, the enhancement of the MR ratio was observed up to ∼50%, which has not been explained by previous theoretical studies. The enhancement is induced by higher-order cotunneling. Power-law dependence of an electric current for a bias voltage (I∼ V2N-1; N is an order of cotunneling) was observed in the Coulomb gap, which corroborates that at maximum fifth-order cotunneling is attributed to the enhancement of the MR ratio.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 2009 Jun 1|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics