Surface and interface structures and magnetic properties of Ni and Ni ₇₅Fe₂₅ thin films on polyethylene naphthalate Organic Substrates

We have investigated structural and magnetic properties of Ni and Ni ₇₅Fe₂₅ thin films evaporated on polyethylene naphtalate (PEN) organic substrates, which can be expected as electrodes of our proposed nanoscale junctions utilizing thin-film edges. As a result, there is no diffusion of Ni and Fe atoms into PEN substrates, resulting in clear and smooth formation of the interface. The surface roughness is also as small as 0.28-0.37 nm in the same scanning scale as the film thickness. As for the magnetic properties, the squareness of the hysteresis loop is as small as 0.24 for Ni/PEN, where there is no observation of the anisotropy magnetoresistance (AMR) effect. In contrast, the squareness of the hysteresis loop is as large as 0.95 for Ni₇₅Fe₂₅/PEN, where the AMR effect has been successfully obtained. These experimental results indicate that Ni ₇₅Fe₂₅/PEN is a promising material for use in electrodes of nanoscale junctions from the viewpoint of structural and magnetic properties.