Experimental observation of drumhead surface states in SrAs3

M Mofazzel Hosen,Dariusz Kaczorowski,Krzysztof Gofryk,Christopher Sims,Sabin Regmi,Arun Bansil,Narayan Poudel,Firoza Kabir,Madhab Neupane,Baokai Wang,Klauss Dimitri,Gyanendra Dhakal

doi:10.1038/s41598-020-59200-2

Abstract

The topological nodal-line semimetal (TNS) is a unique class of materials with a one dimensional line node accompanied by a nearly dispersionless two-dimensional surface state. However, a direct observation of the so called drumhead surface state within current nodal-line materials is still elusive. Here, using high-resolution angle-resolved photoemission spectroscopy (ARPES) along with first-principles calculations, we report the observation of a topological nodal-loop (TNL) in SrAs3, whereas CaAs3 exhibits a topologically trivial state. Our data reveal that surface projections of the bulk nodal-points are connected by clear drumhead surface states in SrAs3. Furthermore, our magneto-transport and magnetization data clearly suggest the presence (absence) of surface states in SrAs3 (CaAs3). Notably, the observed topological states in SrAs3 are well separated from other bands in the vicinity of the Fermi level. RAs3 where R = Ca, Sr, thus, offers a unique opportunity to realize an archetype nodal-loop semimetal and establish a platform for obtaining a deeper understanding of the quantum phase transitions.

Highlights

The topological nodal-line semimetal (TNS) is a unique class of materials with a one dimensional line node accompanied by a nearly dispersionless two-dimensional surface state
The nodal-loop states in PbTaSe219, and Cu3PdN21 lie in the vicinity of other metallic bands, LaN requires multiple symmetries for protection, while in the ZrSiX-type systems the topological states lie above the Fermi level
It has been recently shown that time-reversal symmetry (TRS) with a center of inversion symmetry (CIS) is sufficient, in principle, to protect a nodal-line state[28,29,30]

Summary

Introduction

The topological nodal-line semimetal (TNS) is a unique class of materials with a one dimensional line node accompanied by a nearly dispersionless two-dimensional surface state. We report the experimental observation of a topological nodal-loop state in the monoclinic system SrAs3 and a trivial state in the triclinic system CaAs3 in its (010) surface.

Results

Conclusion