Fabrication of suspended nanogap electrodes and application for future electronics based on nanoscale materials

Abstract

We have reproducibly fabricated suspended tungsten carbide electrodes with a gap of less than 2 nm on a suspended silicon nitride membrane with a slit. Our fabrication technique is based on the local deposition of tungsten carbide by a focused ion beam (FIB). The gap length can reach about 1 nm, which corresponds to the size of a single molecule such that of a fullerene. Using the nano-gap electrode, low-temperature transport measurements through molecules of Gd metallofullerenes between superconducting suspended electrodes are performed. We find that a junction containing a single metallofullerene dimer between superconducting electrodes shows signs of proximity-induced superconductivity. The experimental results depicting the temperature and magnetic field dependences can be understood as the spin state correlation between the metallofullerenes.