  We implemented a nuclear magnetic resonance (NMR) study on rubrene(C42H28)-Co
nano-composites that exhibit an enhanced magnetoresistance (MR) ratio of 80%.
The 59Co NMR spin echo experiment enabled clarification of the hyperfine field
of Co at the interface between the ferromagnet and the molecules, which has not
been investigated for molecular spintronics. An enhanced hyperfine field of the
Co was observed in the rubrene-Co nano-composites, which may be related to the
enhancement of the MR ratio. This study demonstrates the importance of
microscopic investigation of the interface between molecules and ferromagnets
that governs spin-dependent transport in molecular spin devices.
