Realization of a New Topological Crystalline Insulator and Lifshitz Transition in PbTe

Topological materials boast exotic metallic surface states with linear dispersion and spin‐momentum locking, which makes them potential candidates for dissipationless electronic and spintronic devices. Here, it is theoretically predicted that intrinsic Te antisite defects (Te_Pb) in the narrow‐gap semiconductor PbTe induce a band inversion, turning it into a topological crystalline insulator (TCI). To experimentally verify the exotic properties, Te_Pb antisites are introduced into PbTe crystals via nonstoichiometric growth by molecular beam epitaxy. Semimetallic resistivity and distinct quantum oscillations are observed on the Te_Pb doped PbTe. Most importantly, a π Berry phase is unambiguously revealed by a Landau index analysis, demonstrating the Dirac fermion nature of the topological surface states. The discovered TCI nature in Te_Pb doped PbTe is further explored using magneto‐transport measurements under external pressure, and the theoretical calculations of band structures with applying pressure indicate a pressure‐induced Lifshitz transition. Besides, it is proposed that the contribution of bulk states to transport can be reduced by enlarging the inverted gap with strain.