Electronic structure of a nodal line semimetal candidate TbSbTe

The $Ln\mathrm{SbTe}$ ($Ln$ = Lanthanides) family, like isostructural ZrSiS-type compounds, has emerged as a fertile playground for exploring the interaction of electronic correlations and magnetic ordering with the nodal line band topology. Here, we report on a detailed electronic band structure investigation of TbSbTe, corroborated by electrical transport, thermodynamic, and magnetic studies. Temperature-dependent magnetic susceptibility and thermodynamic transport studies indicate the onset of antiferromagnetic ordering below ${T}_N\ensuremath{\sim}5.8\phantom{\rule{0.16em}{0ex}}\mathrm{K}$. The electronic band structure study, carried out with high-resolution angle-resolved photoemission spectroscopy measurements aided with density functional theory--based first-principles calculations reveal presence of a nonsymmorphic symmetry-protected Dirac crossing in the $\mathrm{\ensuremath{\Gamma}}$-X high-symmetry (HS) direction, which is part of a nodal line along the X-R HS direction. Another Dirac crossing occurs along the $\mathrm{\ensuremath{\Gamma}}$-X direction at a relatively higher binding energy, which occurs from ${\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{\mathcal{C}}}_{2\ensuremath{\nu}}\mathcal{P}$ symmetry which is gapped in the theoretical calculations with the effect of spin-orbit coupling considered. Parallel to this direction, our theoretical calculations and experimental results exhibit strongly momentum-dependent surface bands. In this paper, we open an avenue to further uncover the intricate interplay among symmetry-protected topological band structure, spin-orbit coupling, and magnetism in this material and the $Ln\mathrm{SbTe}$ family, in general.