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We report the experimental results of magnetotransport on the single crystal ${\mathrm{MoGe}}_{2}$, which was theoretically predicated to be a topological insulator. The resistivity of ${\mathrm{MoGe}}_{2}$ exhibits a metallic behavior at zero field, while with magnetic fields applied along the $z$ axis and perpendicular to current, ${\mathrm{MoGe}}_{2}$ presents an upturn resistivity behavior and unsaturated quadratic large magnetoresistance (MR). The analysis of Hall effect shows that ${\mathrm{MoGe}}_{2}$ is a compensated semimetal with high mobilities at low temperatures, which is the origin of resistivity upturn and unsaturated large MR. As magnetic fields parallel to current, ${\mathrm{MoGe}}_{2}$ shows a weak antilocalization effect at low fields and a pronounced negative MR at higher fields, which is analogous to the picture of the Adler-Bell-Jackiw axial anomaly. Our results indicate that ${\mathrm{MoGe}}_{2}$ is a topological semimetal rather than a topological insulator, and will encourage further theoretical and experimental investigations on this compound.

We report the magnetotransport properties and the electronic structure of $\mathrm{Na}{\mathrm{Cd}}_{4}{\mathrm{As}}_{3}$ single crystal. The electric resistivity of $\mathrm{Na}{\mathrm{Cd}}_{4}{\mathrm{As}}_{3}$ exhibits a metallic behavior. Clear Shubnikov--de Haas (SdH) oscillations have been observed at low temperatures and high magnetic fields. A single fundamental frequency and small cyclotron effective mass are obtained from the analysis of SdH oscillations, which originate from an ellipsoidal Fermi surface. The Hall resistivity reveals the multiband nature at low temperature and the electron carriers dominate the transport properties. First-principles calculations show that the electronic structure of $\mathrm{Na}{\mathrm{Cd}}_{4}{\mathrm{As}}_{3}$ undergoes a topological phase transition from topological crystalline insulator (TCI) to topological insulator (TI) induced by the structural phase transition. The breaking of mirror symmetry is considered to play a key role in the topological phase transition. Our findings show that $\mathrm{Na}{\mathrm{Cd}}_{4}{\mathrm{As}}_{3}$ is a suitable platform to study the effect of mirror symmetry on the band topology of TCI.