Angle-Resolved Photoemission Spectroscopy and Shubnikov-de Haas Measurements of Ca₃Pb_1-xBi_xO

Recently, there has been a growing interest in the cubic antiperovskite family as potential source of such novel topological phases of matter as three-dimensional (3D) massive Dirac fermions, topological crystalline insulators, topological nodal line semimetals, and topological superconductors. In particular, recent theoretical calculations on Ca₃PbO predict the presence of a 3D gapped Dirac-like cone at finite momentum along the Γ-X direction, which results from a band inversion of the Ca 3d and Pb 6p bands at the Γ point. We employ soft x-ray angle-resolved photoemission spectroscopy (ARPES) to experimentally observe the Dirac-like dispersion along the Γ-X direction in the Brillouin zone of bulk Ca₃PbO. By comparing these results with those for Bi-doped Ca₃PbO, we show that Bi doping is effective in tuning the Fermi level of Ca₃PbO without fundamentally changing its Dirac-like band structure [1]. In addition, we report magnetotransport and tunnel diode oscillation measurements in pulse magnet fields up to 55 T at temperatures between 2 K and 200 K. From the observed quantum oscillations, we confirm the bulk 3D Fermi surface with a nontrivial Berry phase shift and very light effective masses. [1] Y. Obata et al., Phys. Rev. B 96, 155109 (2017), doi: 10.1103/PhysRevB.96.155109.