Enhancements of the 3/2 and 5/2 frequencies of de Haas–van Alphen oscillations near the Lifshitz transition in a two-dimensional compensated metal with overtilted Dirac cones

We study the de Haas-van Alphen (dHvA) oscillations in the two-dimensional compensated metal with overtilted Dirac cones near the Lifshitz transition. We employ the tight-binding model of α−(BEDT−TTF)2I3, in which the massless Dirac fermions are realized. When a uniaxial pressure (P) along the y axis is applied above P≃0.2 kbar in α−(BEDT−TTF)2I3, one electron pocket, which encloses the overtilted Dirac points, is changed to two electron pockets, i.e., Lifshitz transition happens, while a hole pocket does not change a topology. We show that the Fourier components corresponding to the 3/2 and 5/2 areas of the hole pocket are anomalously enhanced in the region of pressure where the Lifshitz transition occurs. This phenomenon will be observed in the two-dimensional overtilted Dirac fermions near the Lifshitz transition.