Quantized thermoelectric Hall plateau in the quantum limit of graphite as a nodal line semimetal

Abstract

We performed thermoelectric Hall conductivity $α_{xy}$ measurements on single-crystal graphite in the quantum limit up to 13 T. Both electrical and thermoelectric transport measurements were performed on the same crystal to extract pure $α_{xy}$, avoiding any sample quality dependence. The $α_{xy}$ converges to a plateau in the quantum limit with a linear dependence on temperature. This behavior is analogous to the quantized thermoelectric Hall effect (QTHE) observed in three-dimensional Dirac/Weyl nodal-point semimetals, and experimentally confirms a theoretical proposal on the QTHE in semimetals with nodal lines as in graphite.