Kagome Metal GdNb$_6$Sn$_6$: A 4d Playground for Topological Magnetism and Electron Correlations

TL;DR

This paper reports the synthesis and characterization of GdNb$_6$Sn$_6$, a kagome metal exhibiting topological electronic features, magnetic frustration, and electron correlations, highlighting its potential for studying complex quantum phenomena.

Contribution

It introduces GdNb$_6$Sn$_6$ as a new kagome metal with detailed experimental and theoretical analysis of its magnetic, electronic, and topological properties.

Findings

Magnetic transition near 2.3 K

Metallic behavior with positive magnetoresistance

Multiple topologically nontrivial band crossings

Abstract

Magnetic kagome metals have garnered considerable attention as an ideal platform for investigating intrinsic topological structures, frustrated magnetism, and electron correlation effects. In this work, we present the synthesis and detailed characterization of GdNb$_6$Sn$_6$, a metal that features a niobium-based kagome lattice and a frustrated triangular gadolinium network. The compound adopts the HfFe$_6$Ge$_6$-type crystal structure, with lattice parameters of a = b = 5.765(4) {\AA} and c = 9.536(8) {\AA}. Magnetic susceptibility and specific heat measurements reveal a magnetic transition near 2.3 K. Electrical transport data confirm metallic behavior, unsaturated positive magnetoresistance, and a hole-dominated multiband Hall effect. Furthermore, first-principles calculations indicate that Nb-4d orbitals predominantly contribute to the electronic states near the Fermi energy, with the band structure showing multiple topologically nontrivial crossings around the Fermi surface. This study also compares GdNb$_6$Sn$_6$ with GdV$_6$Sn$_6$, highlighting their similarities and differences. Our findings pave the way for exploring RNb$_6$Sn$_6$ (R = rare earth) with customized substitutions of R sites to fine-tune their properties.