Zirconium pentatelluride was recently reported to be a 3D Dirac semimetal, with a single conical band, located at the center of the Brillouin zone. The cone's lack of protection by the lattice symmetry immediately sparked vast discussions about the size and topological/trivial nature of a possible gap opening. Here we report on a combined optical and transport study of ZrTe5, which reveals an alternative view of electronic bands in this material. We conclude that the dispersion is approximately linear only in the a-c plane, while remaining relatively flat and parabolic in the third direction (along the b axis). Therefore, the electronic states in ZrTe5 cannot be described using the model of 3D Dirac massless electrons, even when staying at energies well above the band gap 6 meV found in our experiments at low temperatures.
@article{arxiv.1905.00280,
title = {Two-dimensional conical dispersion in ZrTe5 evidenced by optical spectroscopy},
author = {E. Martino and I. Crassee and G. Eguchi and D. Santos-Cottin and R. D. Zhong and G. D. Gu and H. Berger and Z. Rukelj and M. Orlita and C. C. Homes and Ana Akrap},
journal= {arXiv preprint arXiv:1905.00280},
year = {2019}
}