Direct observation of transition from Tomonaga–Luttinger liquid states to superconductive phase in carbon nanotubes

We report the direct observation of the transition from the Tomonaga–Luttinger liquid (TLL) states to the superconductive (SC) phase in partially end-bonded multi-walled carbon nanotubes, in which the SC phase and the TLL states interplay. Two different transition behaviors are observed when the temperature decreases: (1) a drastic increase in the Luttinger parameter g toward g=1 in the power laws on non-normalized differential conductance (dl/dv) vs. voltages and (2) a deviation from the TLL formula in the low voltage-energy region of normalized dl/dv vs. eV/kT. These findings shed light on understanding of one-dimensional electron correlations.