Observation of a topological 3D Dirac semimetal phase in high-mobility Cd3As2

摘要

Experimental identification of three-dimensional (3D) Dirac semimetals insolid state systems is critical for realizing exotic topological phenomena andquantum transport such as the Weyl phases, high temperature linear quantummagnetoresistance and topological magnetic phases. Using high resolutionangle-resolved photoemission spectroscopy, we performed systematic electronicstructure studies on well-known compound Cd3As2. For the first time, we observea highly linear bulk Dirac cone located at the Brillouin zone center projectedonto the (001) surface which is consistent with a 3D Dirac semimetal phase inCd3As2. Remarkably, an unusually high Dirac Fermion velocity up to 10.2\textrm{\AA}{\cdot}$eV (1.5 \times 10^{6} ms^-1) is seen in samples where themobility far exceeds 40,000 cm^2/V.s suggesting that Cd3As2 can be a promisingcandidate as a hypercone analog of graphene in many device-applications whichcan also incorporate topological quantum phenomena in a large gap setting. Ourexperimental identification of this novel topological 3D Dirac semimetal phase,distinct from a 3D topological insulator phase discovered previously, paves theway for exploring higher dimensional relativistic physics in bulk transport andfor realizing novel Fermionic matter such as a Fermi arc nodal metal.