High-field magnetoresistance in nanowire organic spin valves

Abstract

In this paper, we report high-field magnetoresistance measurements on template-grown nanowire organic spin valves in which tris-8 hydroxyquinoline aluminum (Alq${}_{3}$) is sandwiched between two ferromagnetic electrodes: nickel (Ni) and cobalt (Co). We report a magnetoresistance effect in which the resistance changes considerably in the field range where both ferromagnets have parallel magnetizations. We show that this effect does not originate from organic magnetoresistance or the anisotropic magnetoresistance effect of the ferromagnets. Instead, the observed effect can be explained by invoking magnetic-field-dependent spin-diffusion length, where spin diffusion takes place primarily via the Elliott-Yafet mode. These data support the view expressed by some previous reports that Elliott-Yafet is the dominant spin-relaxation mode in template-grown organic nanowires.