Defect states dependence of spin transport in iron phthalocyanine spin valves

Abstract

We fabricated spin-valve devices with a Co/iron phthalocyanine (FePc)/Co stacking structure. The spin-transport properties were systemically studied by varying the measurement temperature and magnetoresistance was confirmed. The estimated value of the spin-diffusion length for the FePc layer is around 30 nm. The existence of defect states was demonstrated based on the analysis of current-voltage curves. Carrier mobilities in the devices were calculated following a trap-filled space charge limited current model, showing the mobility could be up to $2.95\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{2}/\mathrm{Vs}$ at 290 K. The molecular orientation growth of FePc on Co and the interfacial interaction for FePc/Co are also discussed. This work deepens the understanding of spin transport in organic spin devices.