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Resonant magnetoresistance in organic spin-valves

Alexandre Reily Rocha·Stefano Sanvito
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Abstract

We investigate theoretically the effects of surface states over the magnetoresistance of Ni-based organic spin-valves. In particular we perform {\it ab initio} electronic transport calculations for a benzene-thiolate molecule chemically attached to a Ni [001] surface and contacted either by Te to another Ni [001] surface, or terminated by a thiol group and probed by a Ni STM tip. In the case of S- and Te-bonded molecules we find a large asymmetry in the spin-currents as a function of the bias, although the $I$-$V$ is rather symmetric. This leads to a smooth although not monotonic dependence of the magnetoresistance over the bias. In contrast, in the case of a STM-type geometry we demonstrate that the spin-current and the magnetoresistance can be drastically changed with bias. This is the result of a resonance between a spin-polarized surface state of the substrate and the $d$-shell band-edge of the tip.

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Alexandre Reily Rocha, Stefano Sanvito. 2006-10-31. Resonant magnetoresistance in organic spin-valves. https://arxiv.org/abs/cond-mat/0610866

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