This work presents nanoscale four-probe measurements on metallic nanowires using independently controlled scanning tunnelling microscope tips. This technique has allowed us to follow the change in resistance with probe separation. Gold, zinc and nickel nanowires were grown by electrodeposition within porous polycarbonate membranes. Their structure and composition were studied by transmission electron microscopy. Four-probe electrical transport measurements were taken using four independently controlled scanning tunnelling microscope tips positioned using a high resolution scanning electron microscope. Multiple I–V measurements were taken at varying tip separations, on each nanowire, and the change in resistance with separation was observed to be in good agreement with predictions based on the nanowire geometry. The resistivity values of the nanowires were found to be close to bulk values.

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We present an improved method for fabricating tungsten STM tips for measuring nanoscale objects using a multiprobe STM. The tips were prepared by a 'drop-off' technique combined with a magnetic field. For magnetic field strengths above 150 Oe the electrolyte was seen to rotate about the tungsten anode. This rotation reduced the adhesion of bubbles and led to a reduction in the cone angle of the tips produced. This property is advantageous for multiprobe measurements as it allows one to bring multiple tips into close proximity.

This work opens up the possibility of generating microbubble preparations tailored to specific applications with optimised MR sensitivity, in particular MRI based in-vivo manometry.