Gapped Dirac semimetal with mixed linear and parabolic dispersions

Abstract

In this paper, we make a comprehensive study of the properties of a gapped Dirac semimetal model, which was originally proposed in the magnetoinfrared spectroscopy measurement of ZeTe5, and includes both the linear and parabolic dispersions in all three directions. We find that, depending on the band inversion parameters, ζ and ζ z , the model can support three different phases: the single Dirac point (DP) phase, the double DPs phase and the Dirac ring phase. The three different phases can be distinguished by their low-energy features in the density of states (DOS) and optical conductivity. At high energy, both the DOS and optical conductivity exhibit power-law like behaviors, with the asymptotic exponents depending heavily on the signs of ζ and ζ z . Moreover, the thumb-of-rule formula between the DOS and optical conductivity is satisfied only when (ζ , ζ z ) > 0. The implications of our results for experiments are discussed.

Magneto-optic signatures in the gapped Dirac semimetal with mixed linear and parabolic dispersions of ZrTe5

“…), as reported in our previous study [29]. It can be checked that the energy gaps at the Γ and ζ points are given as…”

Magneto-transport evidence for strong topological insulator phase in ZrTe5

“…Since condition ( 5) is only possible when the band is inverted (B z > 0), the existence of a second extremum can serve as a criterion to identify band inversion 16 . We further note that even though our model can be broadly applied to most topological materials [9][10][11][12]14,15 and broader topological phases 17 , it is generally easier to satisfy the requirement for a discernible bandgap at the ζ point in layered materials such as ZrTe 5 , HfTe 5 , Bi 2 Te 3 , and Sb 2 Te 3 , as the weak coupling between layers naturally leads to a smaller v F along the layer stacking direction 10,16,18 .…”

Magneto-transport evidence for strong topological insulator phase in ZrTe5

“…Since condition ( 5) is only possible when the band is inverted (B z > 0), the existence of a second extremum can serve as a criterion to identify band inversion [17]. We further note that even though our model can be broadly applied to most topological materials [9,10,12,11,14,15] and broader topological phases [16], it is generally easier to satisfy the requirement for a discernible bandgap at the ζ point in layered materials such as ZrTe 5 , HfTe 5 , Bi 2 Te 3 , and Sb 2 Te 3 , as the weak coupling between layers naturally leads to a smaller v F along the layer stacking direction [10,17,18].…”