  Having been a ground for various topological fermionic phases, the family of
ZrSiS-type 111 materials has been under experimental and theoretical
investigations. Within this family of materials, the subfamily LnSbTe (Ln =
lanthanide elements) is gaining interests in recent times as the strong
correlation effects and magnetism arising from the 4f electrons of the
lanthanides can provide an important platform to study the linking between
topology, magnetism, and correlation. In this paper, we report the systematic
study of the electronic structure of SmSbTe - a member of the LnSbTe subfamily
- by utilizing angle-resolved photoemission spectroscopy in conjunction with
first-principles calculations, transport, and magnetic measurements. Our
experimental results identify multiple Dirac nodes forming the nodal-lines
along the G- X and Z- R directions in the bulk Brillouin zone (BZ) as predicted
by our theoretical calculations. A surface Dirac-like state that arises from
the square net plane of the Sb atoms is also observed at the X point of the
surface BZ. Our study highlights SmSbTe as a promising candidate to understand
the topological electronic structure of LnSbTe materials.
