Atom-like behaviors and orbital-related Tomonaga-Luttinger liquids in carbon nano-peapod quantum dots

We report ballistic charge transport phenomena observed in carbon nano-peapod quantum dots. We find atom-like behaviors (shell filling) sensitive to applied back-gate voltages (Vbg) by single electron spectroscopy. Doubly degenerate electronic levels are found only around ground states at very low Vbg. Those correlations with the presence of nearly free electron states unique to the peapods are discussed. Moreover, we find power laws in conductance versus energy relationships with anomalously high values of power, which are strongly associated with shell filling to the doubly degenerate levels. It is investigated that the powers originate from Tomonaga-Luttinger liquid via the occupied doubly degenerate levels. These results imply that a ballistic charge transport is still preserved at low-Vbg regions in carbon nano-peapod quantum dots in spite of the presence of the encapsulated C60 molecules.