Unusual Transport Properties of CNT-Nickelocene-Based Circuits: Role of Structural Symmetry.

At the nano- or molecular scale, electron transport is often governed by quantum effects, for which the symmetry of the system could become a key factor. In this work, by state-of-the-art first-principles modeling and simulation, we show that the structural symmetry plays a unique role in properties of electronic circuits made of CNT (5,5) electrodes and nickelocene (NiCp) molecules, resulting in unusual transport phenomena beyond the classical circuit theories. For a single NiCp molecule sandwiched between two CNT (5,5) electrodes, we find that the symmetry change caused by the rotation of one CNT electrode greatly affects the conductance of the device, which may have important implications for understanding the performances of CNT-based quantum devices. We further show that when two NiCp molecular resistors are connected in series, the conductance of the resulting series-NiCp circuit can be significantly higher than the single-NiCp device at certain biases, in which the structural symmetry of the circuit plays a critical role. These results provide new opportunities for the future design of molecular devices with novel functions.