Mechanical Control of Quantum Transport in Single-wall Carbon Nanotubes

Single-wall carbon nanotubes (SWCNTs) are effectively narrow ribbons of graphene with atomically precise edges. They are ideal systems to harness quantum transport straintronics (QTS), i.e. using mechanical strain to control quantum transport. We first present an applied theory [1] to study QTS in uniaxially-strained quasi-metallic-SWCNT transistors, and then present recent experimental measurements in agreement with the model.



Our model shows that the large subband energy spacing in SWCNTs (∼0.8 eV) leads to transistors with a single quantum transport channel. Mechanical strain adds both scalar φ and vector A gauge potentials to the transistor’s Hamiltonian. These potentials create a rich spectrum of quantum interferences in the conductance, which can be described as a mechanical Aharonov-Bohm effect. The charge carriers’ quantum phase can be controlled by purely mechanical means. For instance, a full 2π phase shift can be induced in a (12,9) tube by a 0.7 % strain change. Lastly, we present recent experimental transport data on three strain-tunable SWCNT transistors (d ~ 1.5 nm, and L ~ 30 nm) at low temperature. The data show that the conductance and quantum interferences are mechanically tunable. [1] L. Huang, G. Wei, and A. R. Champagne, arXiv:2408.10355.