Molecular spintronics using nano-carbon and pi-electron molecules

摘要

Molecular spintronics garners much attention in recent several years, and various molecules have been intensively studied after an observation of an MR effect via multi-walled carbon nanotubes [1]. Molecules consist of light elements (carbon and hydrogen), which enables to expect long spin coherent length and time if spins are efficiently injected. This physical feature can yield molecular spin transistors and quantum computation devices. However, reproducibility and reliability in most of previous studies were still controversial, which was mainly due to a poor interface formation between molecules and ferromagnets. In order to bypass the interface problem, we have introduced molecule-ferromagnet nano-composites, where Co nano-particles were uniformly embedded into a molecular matrix. The MR effect via molecules was observed in a broader temperature range, it was clarified that the MR effect was due to spin-dependent tunneling probably because of conductance mismatch. Thus, we focused on graphene as a channel layer in molecular spin valves. We have observed clear spin injection and precession signals by introducing a non-local technique.