Anomalous Coulomb diamonds and power-law behavior sensitive to back-gate voltages in carbon nanoscale peapod quantum dots

J. Mizubayashi, J. Haruyama, I. Takesue, T. Okazaki, H. Shinohara, Y. Harada, Y. Awano
2007 Physical Review B  
We report anomalous charging effect of single electrons ͑Coulomb diamonds͒ observed in carbon nanoscale peapod quantum dots that encapsulate a series of C 60 molecules. We find that behaviors of diamonds are anomalously sensitive to back-gate voltages ͑V bg ͒, exhibiting two evidently different V bg regions and a large polarity on V bg . In particular, we find only a sequence of one large diamond followed by three smaller ones existing around ground state. Magnetic-field dependence indicates
more » ... ndence indicates the presence of shell filling by spin singlet to doubly degenerate electronic levels for these. The encapsulated-C 60 molecules indirectly affect this shell filling at low V bg possibly via nearly free electrons. In contrast, they act as individual quantum dots coupled in series in high V bg region. It directly contributes to highly overlapped very large diamonds. Moreover, we report power-law behaviors on conductance versus energy relationships observed in the same carbon nanoscale peapods. We find that the values of powers are also highly sensitive to applied V bg with three different regions and anomalously high at high source-drain voltages. Because the power laws are found at voltages, which are the nearest outside of the above-mentioned fourfold Coulomb diamonds, correlation of the anomalous powers with orbital-related Tomonaga-Luttinger liquid is discussed.
doi:10.1103/physrevb.75.205431 fatcat:vo3ev533ajdepgurjred66viki