Universal conductance fluctuations in Dirac semimetalCd3As2nanowires

Abstract

Three-dimensional Dirac semimetals host bulk Dirac fermions characterized by a linear dispersion relation in momentum space along all three dimensions. It has been theoretically predicted that the breaking of ${C}_{4}$ rotational crystalline symmetry in the Dirac semimetal $\mathrm{C}{\mathrm{d}}_{3}\mathrm{A}{\mathrm{s}}_{2}$ may give rise to the massive Dirac fermions. Here we report the phase-coherent transport in $\mathrm{C}{\mathrm{d}}_{3}\mathrm{A}{\mathrm{s}}_{2}$ nanowires studied by measuring the universal conductance fluctuations (UCFs). It is found that the UCF amplitude is largely suppressed at the Dirac point by sweeping the magnetic field at different gate voltages, which is ascribed to the breaking of the ${C}_{4}$ rotational symmetry-induced band-gap opening. The temperature dependence of resistance demonstrates a magnetic-field-induced metal-insulator transition, consisting of the band-gap opening. Moreover, the UCF amplitude is reduced by a factor of $\ensuremath{\sim}2\sqrt{2}$ in the presence of a magnetic field, suggesting the phase transition from a Dirac-to-Weyl semimetal by breaking time-reversal symmetry.