We report the topological transition by gate control in a ${\mathrm{Cd}}_{3}{\mathrm{As}}_{2}$ Dirac semimetal nanowire Josephson junction with diameter of about 64 nm. In electron branch, quantum confinement effect enforces surface band into series gapped subbands and thus nontopological states. hole however, because mean free path is smaller than perimeter, inoperative property maintained. Th...

Dirac semimetals host three-dimensional (3D) Dirac fermion states in the bulk of crystalline solids, which can be viewed as 3D analogs of graphene. Owing to their relativistic spectrum and unique topological character, these materials hold great promise for fundamental-physics exploration and practical applications. Particularly, they are expected to be ideal parent compounds for engineering va...

Graphene is known as a two-dimensional Dirac semimetal, in which electron states are described by the Dirac equation of relativistic quantum mechanics. Three-dimensional analogs of graphene are characterized by Dirac points or lines in momentum space, which are protected by symmetry. Here, we report a novel 3D carbon allotrope belonging to a class of topological nodal line semimetals, discovere...