  Synergic effect of electronic correlation and spin-orbit coupling is an
emerging topic in topological materials. Central to this rapidly developing
area are the prototypes of strongly correlated heavy-fermion systems. Recently,
some Ce-based compounds are proposed to host intriguing topological nature,
among which the electronic properties of CeSb are still under debate. In this
paper, we report a comprehensive study combining magnetic and electronic
transport measurements, and electronic band structure calculations of this
compound to identify its topological nature. Quantum oscillations are clearly
observed in both magnetization and magnetoresistance at high fields, from which
one pocket with a nontrivial Berry phase is recognized. Angular-dependent
magnetoresistance shows that this pocket is elongated in nature and corresponds
to the electron pocket as observed in LaBi. Nontrivial electronic structure of
CeSb is further confirmed by first-principle calculations, which arises from
spin splitting in the fully polarized ferromagnetic state. These features
indicate that magnetic-field can induce nontrivial topological electronic
states in this prototypical Kondo semimetal.
