Stable iron-group metal nano contact showing quantized conductance in solution

The electrical conductance of the iron-group metal (Fe, Co, and Ni) nano contacts was measured under the electrochemical potential control. The iron-group metal nano contacts were fabricated by moving the scanning tunneling microscope (STM) tip into and out of contact with the metal substrate, on which iron-group metal was electrochemically deposited. Broad 1–1.5G0 (G0 = 2e2/h) and sharp 1.3 G0 features were observed in the conductance histograms of the Ni and Co nano contacts. These clear features were not observed in the conductance histogram of the Fe nano contacts. The observed quantized conductance behavior agreed well with that previously observed for the clean monoatomic contacts prepared in ultra high vacuum (UHV) at 4.2 K. Present results prove that the stable iron-group monoatomic contacts could be stabilized in solution at room temperature under the electrochemical potential control.