Kai-He Ding, Zhen-Gang Zhu, Yong-Le Hu, and Gang Su

Physical Review B 104, 155135 (2021)-Published 21 October 2021

ABSTRACT

Dirac point plays a crucial role in regulating electronic properties of topological semimetals. In two dimensions, the manipulation of Dirac points can spur a transition from Dirac semimetal through semi-Dirac phase to a gapped phase. Across such a so-called Lifshitz transition, we find that the quantum interference corrections to the conductivity δσ_xx and δσ_yy are always negative, giving rise to a weak localization behavior. The ratio δσ_xx/δσ_yy undergoes a transition from linear to parabolic dependence on the merging parameter across the Lifshitz transition, which leads to a crossover of the temperature dependence of the inverse inelastic scattering time 1/T_ε from ∼T to ∼ T ln(T₀/T ). This fingerprint behavior can be readily tested experimentally through merging Dirac points in two-dimensional lattices. This work presents an alternative perspective to understand weak localization through Lifshitz transition.