Theoretical design of topological hetero-nanotubes.

We propose and investigate the idea of topological heteronanotubes (THTs) for realizing an one-dimensional (1D) topological material platform that can pave the way to low-power carbon nanoelectronics at room temperature. We predict that the coaxial double-wall heteronanotube, a carbon nanotube (CNT) inside a boron nitride nanotube (BNNT), can act as a THT. Dissipationless topological conducting pathways on the THT are protected by a valley-dependent topological invariance that originates from local topological phase transitions of the CNT modulated by the CNT-BNNT interaction. Spiral THTs, where topological current flows spirally around the tube, function as nanoscale solenoids to induce remarkable magnetic fields due to the dense moire nanopatterning. The generality and robustness of the THT materials are demonstrated by investigating different tube diameters, tube indexes, and tube types as well as topological-pathway orientations through first principles.