Observation of Dirac nodal line states in topological semimetal candidate PrSbTe

Abstract

The interplay among topology, crystal symmetry, magnetic order, and strong electron correlation can give rise to a plethora of exotic physical phenomena. The ZrSiS family is known as typical topological Dirac semimetals, among them $\mathit{Ln}\mathrm{SbTe}$ ($\mathit{Ln}$ denotes lanthanide) compounds exhibit intriguing characteristics due to the presence of $\mathit{Ln} 4f$ electrons, resulting in quantum states and unique properties. In this paper, the topological electronic structure of PrSbTe is systematically studied by angle-resolved photoemission spectroscopy (ARPES), combined with magnetic, specific heat measurements, and band structure calculations. The detailed three-dimensional electronic structure of PrSbTe has been obtained, and a diamond-shaped Fermi surface and multiple Dirac nodal lines have been observed, which are in remarkable agreement with theoretical calculations. Moreover, the $4f$ electrons in PrSbTe are rather localized, which can be revealed by on-resonant ARPES data and further confirmed by the rather small Sommerfeld coefficient of $\ensuremath{\gamma}=2.6231\phantom{\rule{0.16em}{0ex}}\mathrm{mJ}/\mathrm{mol}\phantom{\rule{0.16em}{0ex}}{\mathrm{K}}^{2}$. Our results provide more detailed information about the $\mathit{Ln}\mathrm{SbTe}$ family, which gives a deeper understanding of the interaction between $\mathit{Ln} 4f$ electrons and the topological states.