Lifshitz Transition in Correlated Topological Semimetals

Topological quasiparticles that arise when the chemical potential is near a band crossing are pivotal to next-generation quantum devices. Nonetheless, correlated topological materials frequently host Dirac nodes away from the Fermi level, and the cause of this shift remains elusive. Here, we investigated the electronic structure of YPtBi and GdPtBi through ab initio many-body perturbation GW theory combined with dynamical mean-field theory and theoretically show that the correlation effects of 4 $d$ or 4 $f$ electrons can lead to the formation of hole carriers, thereby shifting the quadratic band-touching points away from the chemical potential. In YPtBi, the weakly correlated Y-4 $d$ electrons constitute the topological bands, and the quadratic band-touching point is at the Fermi level at high temperatures. At low temperatures, enhanced correlations of Y-4 $d$ electrons renormalize the topological bands, leading to the formation of a hole pocket. In GdPtBi, the strongly correlated Gd-4 $f$ electrons form Hubbard-like bands that originate from self-energy effects potentially associated with a topological singularity. These local bands encompass itinerant 4 $f$ bands, which hybridize with the topological bands to induce pronounced hole bands. This concerted effect reduces the hole doping, bringing the chemical potential closer to the quadratic band-touching points as the temperature is lowered. This prediction of temperature-induced Lifshitz transition can be responsible for the large hole bands observed in both topological semimetals in angle-resolved photoemission spectroscopy measurements at low temperatures. Our findings indicate that the integration of correlated fermions within a topological framework can reshape the Fermi surface without defect engineering. These theoretical predictions underscore the importance of direct experimental investigation of the temperature-dependent electronic structure in the topological semimetals.