Universal Temperature Crossover Behavior of Electrical Conductance in a Single Oligothiophene Molecular Wire

We have observed and analyzed a universal temperature crossover behavior of electrical
conductance in a single oligothiophene molecular wire. The crossover between the Arrheniustype
temperature dependence at high temperature and the temperature-invariant behavior at
low temperature is found at a critical molecular wire length of 5.6 nm, where we found a
change from the exponential length dependence to the length-invariant behavior. We have
derived a scaling function analysis for the origin of the crossover behavior. After assuring that
the analysis fits the explanation of the Keldysh Green's function calculation for the
temperature dependence, we have applied it to our experimental results and found
successfully that our scaling function gives a universal description of the temperature
dependence for all over the temperature range.