Observation of multiple nodal-lines in SmSbTe

TL;DR

This study reveals multiple nodal-lines and a surface Dirac state in SmSbTe, a lanthanide-based topological material, combining experimental ARPES data with theoretical calculations to advance understanding of its electronic structure.

Contribution

First comprehensive experimental and theoretical investigation of SmSbTe's electronic structure, identifying multiple nodal-lines and surface states in this topological material.

Findings

Multiple Dirac nodal-lines along G-X and Z-R directions

Observation of a surface Dirac-like state at the X point

SmSbTe exhibits complex topological electronic features

Abstract

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.