Quantum conductance of helical nanowires

Abstract

We have calculated the quantum conductance of N-fold helical metallic nanowires by using recursion-transfer-matrix method. When ${L}_{H}$ (the pitch of the helix) is in a certain range, there appear characteristic humps and dips with steps of ${1G}_{0}$ or ${2G}_{0}$ ${(G}_{0}{=2e}^{2}/h)$ in the conductance. The anomalous conductance originates from the fact that an energy gap opens due to noncircular cross section and shifts toward higher energies with decreasing ${L}_{H}.$