Discovery of topological nodal-line fermionic phase in a magnetic material GdSbTe

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. A majority of discovered topological semimetals are nonmagnetic and conserve time reversal symmetry. Here we report the experimental discovery of an antiferromagnetic topological nodal-line semimetallic state in GdSbTe using angle-resolved photoemission spectroscopy. Our systematic study reveals the detailed electronic structure of the paramagnetic state of antiferromagnetic GdSbTe. We observe the presence of multiple Fermi surface pockets including a diamond-shape, and small circular pockets around the zone center and high symmetry 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 and the effect of magnetism along the nodal-line direction. Interestingly, our experimental data show a robust Dirac-like state both below and above the magnetic transition temperature (TN = 13 K). Having a relatively high transition temperature, GdSbTe provides an archetypical platform to study the interaction between magnetism and topological states of matter.

Charge Density Waves and Magnetism in Topological Semimetal Candidates GdSbxTe2−x−δ

“…The superstructure evolution of GdSb x Te 2− x−δ is related to the magnetic property change, for example, the minimum Néel transition temperature is observed near the commensurate‐to‐incommensurate transition boundary ( x = 0.21). We would like to point out that the previously investigated TSM “GdSbTe” in fact possesses out‐of‐plane lattice parameter and magnetic properties resembling those of GdSb 0.54 Te 1.44 reported in this work. Since the crystals for the study mentioned above were also grown by vapor transport, it is not surprising that off‐stoichiometric samples were synthesized, as all our attempts to synthesize stoichiometric GdSbTe with vapor transport failed.…”

“…This is well‐documented in rare‐earth tritelluride systems . For the GdSb x Te 2− x−δ system it can be inferred from the previously mentioned ARPES study that the Fermi surface also does not fully gap. Recently, we have reported that the very small Fermi surface pockets, which result from a CDW‐induced Fermi surface reconstruction in GdTe 3, exhibit very high mobility and a light effective mass .…”

“…Replacing Ce by other rare‐earth elements might affect the magnetic properties, which is part of the motivation for the study of the analogue GdSbTe. Using angle‐resolved photoemission spectroscopy, GdSbTe has recently been reported to host an antiferromagnetic topological nodal‐line state, but the exact crystal structure as well as magnetic properties have not yet been investigated. Such a study is critical because Ln SbTe phases (with Ln = Lanthanide) are likely to undergo lattice distortions, especially when they are nonstoichiometric.…”

Band Engineering of Dirac Semimetals Using Charge Density Waves

“…[25] In this context, LnSbTe materials (Ln = lanthanide) that are isostructural and isoelectronic to ZrSiS have been suggested as promising candidates as magnetic TSMs. [28][29][30][31][32][33] However, the band structure of these materials is not as "clean" as in ZrSiS: the FS contains trivial pockets, in addition to the nodal-line states.…”

The Role of Delocalized Chemical Bonding in Square-Net-Based Topological Semimetals

“…The compounds in the yellow region are mostly established TSMs, for example ZrSiS and related compounds with M=Zr or Hf, X=Si, Ge, or Sn, and Z=O, S, Se, or Te 29,[47][48][49][50][51]. Other noteworthy compounds in the region are the LnSbTe family (Ln = lanthanide) [52][53][54][55]. On the zone border lies the topological superconductor UTe 2 [56][57][58].…”