Observation of topological nodal-line fermionic phase in GdSbTe

TL;DR

This paper reports the experimental discovery of a topological nodal-line semimetal state in GdSbTe, revealing complex electronic structures and a Dirac-like state that persists across magnetic transition temperatures, advancing understanding of magnetic topological materials.

Contribution

First experimental observation of a topological nodal-line semimetal in GdSbTe, including detailed electronic structure analysis and magnetic state behavior.

Findings

Multiple Fermi surface pockets identified

Presence of a Dirac-like state at the X point

Dirac-like state persists above and below T_N

Abstract

Topological Dirac semimetals with accidental band touching between conduction and valence bands protected by time reversal and inversion symmetry are at the frontier of modern condensed matter research. Theoretically one can get Weyl and/or nodal-line semimetals by breaking either one of them. Most of the discovered topological semimetals are nonmagnetic i.e respect time reversal symmetry. Here we report the experimental observation of a topological nodal-line semi metallic state in GdSbTe using angle-resolved photoemission spectroscopy. Our systematic study reveals the detailed electronic structure of the paramagnetic state of GdSbTe. We observe the presence of multiple Fermi surface pockets including a diamond-shape, an elliptical shape, and small circular pockets around the zone center and high symmetry M and X points of the Brillouin zone (BZ), respectively. Furthermore, we observe the presence of a Dirac-like state at the X point of the BZ. Interestingly, our experimental data shows a robust Dirac like state both below and above the magnetic transition temperature (T_N ~ 13 K). Having relatively higher transition temperature, GdSbTe provides an archetype platform to study the interaction between magnetism and topological states of matter.