Plastic Flowlike Deformation and Its Relation to Aperiodic Peaks in Conductance Histograms of Molybdenum Nanocontacts

Abstract

We observed the tensile deformation of molybdenum (Mo) nanocontacts (NCs) and simultaneously measured their conductance by in situ transmission electron microscopy. During deformation, the contact width decreased from several nanometers to a single-atom size. Mo NCs were thinned via a plastic flowlike deformation process. The process differs from the slip on lattice planes, which is frequently observed in NCs made of noble metals. We plotted histograms of the time-conductance traces measured during the tensile deformation of Mo NCs. In the conductance histograms, we observed peaks at 1.8G 0 (G 0 ＝2e 2 /h, where e is the electron charge and h is Planck's constant), 3.6G 0 , and 4.4G 0 . When the minimum conductance (1.8G 0 ) was measured, the minimum cross-sectional widths of the NCs were 3-7 atoms. These NCs exhibited relaxed structures that formed irregularly after the plastic flowlike deformation occurred in the final stage of the tensile process. We inferred that the aperiodic peaks observed in the conductance histograms originated from irregular variations in the contact areas and atomic configurations of the NCs during the plastic flowlike deformation.Moreover, the conductance value of the single-atom contacts was less than 0.1G 0 .