Planar organic spin valves using nanostructured Ni80Fe20 magnetic contacts

• An in-plane organic spin valve based on Ni80Fe20 nanowires was realised.
• Due to the high shape anisotropy, the switching field of Ni80Fe20 nanowires was controlled only by the wire width.
• Parallel and anti-parallel magnetisation configurations were observed.
• A magnetoresistance of −0.35% was observed at room temperature using PTCDI-C13.

Planar organic spin valves were fabricated by evaporating organic semiconductor PTCDI-C13 onto pairs of patterned Ni80Fe20 magnetic nanowires separated by 120 nm. Control over the relative alignment of magnetisation in the nanowires was achieved by including a domain wall ‘nucleation pad’ at the end of one of the wires to ensure a large separation in magnetic switching fields. Switching behaviour was investigated by optical and X-ray magnetic imaging. Room temperature organic magnetoresistance of −0.35% was observed, which is large compared to that achieved in vertical spin valves with similar materials. We attribute the enhanced performance of the planar geometry to the deposition of the semiconductor on top of the metal, which improves the quality of metal–semiconductor interfaces compared to the metal-on-semiconductor interfaces in vertical spin valves.

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