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TT: Fachverband Tiefe Temperaturen
TT 28: Poster Session: Topological Topics
TT 28.4: Poster
Montag, 12. März 2018, 15:00–19:00, Poster B
Flat Optical Conductivity due to the Dirac nodal line in ZrSiS — •Micha Schilling1, Artem Pronin1, Martin Dressel1, Bettina Lotsch2, and Leslie Schoop2,3 — 11. Physikalisches Institut, Universität Stuttgart, 70569 Stuttgart, Germany — 2Max-Planck-Institute for Solid State Research, 70569 Stuttgart, Germany — 3Department of Chemistry, Princeton University, Princeton, USA
In graphene, the isolated two-dimensional Dirac cones cause a universal (i.e. material-independent) interband optical conductivity: the conductivity is frequency independent and the value is set by the quantum conductance.
In ZrSiS, linear dispersing bands are quasi-two-dimensional and the Dirac points form nodal lines of two types. Spin-orbit coupling (SOC) opens a small gap along one of them. It was theoretically proposed, that the interband conductivity of such a nodal-line semimetal would also exhibit a frequency-independent behavior [1]. The absolute value, however, be material dependent, related to the length of the nodal line.
We investigated the optical response of ZrSiS by the means of Fourier-transform infrared spectroscopy. We measured the reflectivity over a frequency range from 6 to 3000 meV at different temperatures down to 10 K and determined the optical conductivity. Our results confirm the theoretical expectations, revealing flat optical conductivity between 30 and 300 meV. From the measurements we could estimate the length of the nodal line in the reciprocal space and the size of the SOC-induced gap [2].
J. P. Carbotte, J. Phys. Condens. Matter 29, 045301 (2017).
M. B. Schilling et al., Phys. Rev. Lett. 119, 187401 (2017).