Room temperature spin valve effect in highly ordered array of methanofullerene nanotubes

Abstract

Organic spin valve array, with vertically oriented methanofullerene [6, 6]-phenyl C61- butyric acid methyl ester (PCBM) nanotubes as spacer, has been prepared by combining an electrochemical self-assembly with a recently developed fixed angle centrifuge-assisted organic nanowire growth technique. The PCBM nanotubes are ∼325 nm long, have outer shell diameter of ∼70 nm, and inner shell diameter of ∼ 45 nm. In spite of the relatively long channel length, these devices exhibit an inverse spin valve effect, which persists even at room temperature. Spin relaxation length in PCBM nanotubes is relatively temperature-independent and its lower limit is estimated to be ∼50 nm at room temperature. This is the largest room-temperature spin relaxation length in organic nanowire systems, including carbon nanotubes reported to date, and identifies PCBM as a promising material for room temperature organic nanospintronics. Observation of spin valve signals in these devices is due to efficient spin selective transmission at the interfacial Schottky barriers.