Gate-tuned Aharonov-Bohm interference of surface states in a quasiballistic Dirac semimetal nanowire

We report an observation of a topologically protected transport of surface carriers in a quasiballistic Cd3As2 nanowire. The nanowire is thin enough for the spin-textured surface carriers to form 1D subbands, demonstrating conductance oscillations with gate voltage even without magnetic field. The π-phase shift of Aharonov-Bohm oscillations can periodically appear/disappear by tuning gate voltage continuously. Such a π-phase shift stemming from the Berry phase demonstrates the topological nature of surface states. The topologically protected transport of the surface states is further revealed by four-terminal nonlocal measurements.