Flat optical conductivity in ZrSiS due to two-dimensional Dirac bands
| Autor: | Schilling, M. B., Schoop, L. M., Lotsch, B. V., Dressel, M., Pronin, A. V. |
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| Rok vydání: | 2017 |
| Předmět: | |
| Zdroj: | Phys. Rev. Lett. 119, 187401 (2017) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevLett.119.187401 |
| Popis: | ZrSiS exhibits a frequency-independent interband conductivity $\sigma(\omega) = \rm{const}(\omega) \equiv \sigma_{\rm{flat}}$ in a broad range from 250 to 2500 cm$^{-1}$ (30 - 300 meV). This makes ZrSiS similar to (quasi)two-dimensional Dirac electron systems, such as graphite and graphene. We assign the flat optical conductivity to the transitions between quasi-two-dimensional Dirac bands near the Fermi level. In contrast to graphene, $\sigma_{\rm{flat}}$ is not supposed to be universal but related to the length of the nodal line in the reciprocal space, $k_{0}$. When $\sigma_{\rm{flat}}$ and $k_{0}$ are connected by a simple model, we find good agreement between experiment and theory. Due to the spin-orbit coupling, the discussed Dirac bands in ZrSiS possess a small gap $\Delta$, for which we determine an upper bound max($\Delta$) = 30 meV from our optical measurements. At low temperatures the momentum-relaxation rate collapses, and the characteristic length scale of momentum relaxation is of the order of microns below 50 K. Comment: 5 pages |
| Databáze: | arXiv |
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