Evidence of electron correlation induced kink in Dirac bands in a non-symmorphic Kondo lattice system, CeAgSb2

TL;DR

This study investigates how electron correlations affect Dirac fermions in CeAgSb2, revealing a correlation-induced kink in Dirac bands within a non-symmorphic Kondo lattice, suggesting robust topological states despite strong interactions.

Contribution

It provides experimental and theoretical evidence of a correlation-induced kink in Dirac bands in a non-symmorphic Kondo lattice system, highlighting the robustness of topological fermions under strong correlations.

Findings

Dirac bands cross at the Brillouin zone boundary due to non-symmorphic symmetry.

Anisotropic Dirac cones form a diamond-shaped nodal line from Sb 5p states.

Dirac bands remain linear with a high slope, even after hybridization with Ce 4f states, with a small slope reduction due to a kink.

Abstract

We study the behavior of Dirac fermions in the presence of electron correlation in a nonsymmorphic Kondo lattice system, CeAgSb2 employing high-resolution angle-resolved photoemission spectroscopy and first-principles calculations. Experiments reveal crossings of highly dispersive linear bands at the Brillouin zone boundary due to non-symmorphic symmetry. In addition, anisotropic Dirac cones are observed constituted by the squarenet Sb 5p states forming a diamond-shaped nodal line. The Dirac bands are linear in a wide energy range with a unusually high slope and exhibit distinct Dirac point in this highly spin-orbit coupled system. Interestingly, the linearity of the bands are preserved even after the hybridization of these states with the local Ce 4f states, which leads to a small reduction of slope via formation of a 'kink'. These results seed the emergence of an area of robust topological fermions even in presence of strong correlation.