Shubnikov-De Haas Oscillations In The Three-Dimensional Dirac Fermion System Ca3pbo

Cubic antiperovskite Ca3PbO is a candidate for three-dimensional (3D) Dirac fermion systems that have recently emerged as a class of topological materials exhibiting linear energy dispersion in the bulk. We report magnetotransport and tunnel diode oscillation (TDO) measurements on Bi-doped Ca3PbO in magnetic fields up to 55 T and temperatures between 2 and 78 K. By observing the Shubnikov-de Haas (SdH) oscillations, we resolve the bulk 3D Fermi surface (FS) with distinctive features of Dirac fermions including linear magnetoresistance, light effective mass, and a nontrivial phase shift. TDO measurements under high fields reveal the existence of two primary SdH frequencies, one being twice the other. Together with the low effective mass, the oscillations of these two frequencies account for the emergence of the Landau level splitting that persists up to 43 K. The field-angular-dependence of the oscillation frequencies with three branches confirms that the FS is composed of three pairs of hole pockets with uniaxial anisotropy on the Gamma-X path, as predicted for bulk Ca3PbO crystal by density functional theory calculation.