Weyl nodes and Kondo interaction in noncentrosymmetric semimetals RGaGe (R=La, Ce and Pr) with long Fermi arcs

Abstract

In non-centrosymmetric Weyl semimetals based on rare-earth compounds, the correlation effects among $f$ electrons may play a crucial role in shaping the properties of Weyl nodes, potentially giving rise to magnetic Weyl semimetals or correlated Weyl excitations. Here, we investigates a recently identified class of magnetic rare-earth Weyl semimetals, RGaGe (R = La, Ce, and Pr). By employing a combination of density functional theory (DFT) and dynamical mean-field theory (DMFT) calculations, we demonstrate that under ambient pressure, the $f$ electrons in CeGaGe and PrGaGe are nearly fully localized. Concurrently, three inequivalent types of Weyl nodes emerge near the Fermi level due to intersections between $spd$ bands. Notably, one type of Weyl point exhibits substantial chiral separation (significantly greater than in CeAlSi and CeAlGe), leading to the formation of long and well-defined surface Fermi arcs on the (001) surface. These Fermi arcs remain well-separated by bulk states, thereby facilitating future experimental observations. In contrast, the chiral separation of Weyl points in LaGaGe is relatively modest. Upon application of volume compression, the $f$ electrons in CeGaGe progressively become itinerant and begin to obscure the Weyl nodes formed by $spd$ electrons, rendering them less accessible for direct observation. These findings suggest that in correlated materials, particularly $f$-electron systems, even when $f$ electrons do not directly contribute to the formation of topological nodes, they can still exert a profound influence on the characteristics of Weyl nodes.