Two-dimensional Dirac dispersion in the layered compound BaCdSb2

Abstract

We report a comprehensive study of the electronic structure of layered compound $\mathrm{Ba}\mathrm{Cd}{\mathrm{Sb}}_{2}$ by using electrical transport measurements, first-principles calculations, and angle-resolved photoemission spectroscopy (ARPES). The samples show semiconductorlike temperature dependence of resistivity and low carrier density. The Shubnikov-de Haas (SdH) oscillations with a single frequency reveal a small two-dimensional (2D) cylinderlike Fermi surface (FS), a light cyclotron effective mass, and trivial Berry's phase. Quantum limit can be achieved under a moderate magnetic field. The calculated bands without any renormalization are well consistent with the ARPES results, showing the Dirac band crossing with 2D character near the Fermi energy and a gap of about 34 meV at the Dirac point induced by spin-orbit interaction. The SdH oscillations can be identified to the Dirac band by the similar cross sectional areas of FSs. Our findings indicate $\mathrm{Ba}\mathrm{Cd}{\mathrm{Sb}}_{2}$ is a promising material for researching the quantum phenomena of the 2D Dirac fermions.