Enhancements of the 32 and 52 frequencies of de Haas–van Alphen oscillations near the Lifshitz transition in a two-dimensional compensated metal with overtilted Dirac cones

Abstract

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 $\ensuremath{\alpha}\ensuremath{-}{(\mathrm{BEDT}\ensuremath{-}\mathrm{TTF})}_{2}{\mathrm{I}}_{3}$, in which the massless Dirac fermions are realized. When a uniaxial pressure $(P)$ along the $y$ axis is applied above $P\ensuremath{\simeq}0.2$ kbar in $\ensuremath{\alpha}\ensuremath{-}{(\mathrm{BEDT}\ensuremath{-}\mathrm{TTF})}_{2}{\mathrm{I}}_{3}$, 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 $\frac{3}{2}$ and $\frac{5}{2}$ 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.