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arXiv · 2411.10635

Stability frontiers in the AM$_6$X$_6$ kagome metals: The LnNb$_6$Sn$_6$ (Ln:Ce-Lu,Y) family and density-wave transition in LuNb$_6$Sn$_6$

Brenden R. Ortiz·William R. Meier·Ganesh Pokharel·Juan Chamorro·Fazhi Yang·Shirin Mozaffari·Alex Thaler·Steven J. Gomez Alvarado·Heda Zhang·David S. Parker·German D. Samolyuk·Joseph A. M. Paddison·Jiaqiang Yan·Feng Ye·Suchismita Sarker·Stephen D. Wilson·Hu Miao·David Mandrus·Michael A. McGuire
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Abstract

The kagome motif is a versatile platform for condensed matter physics, hosting rich interactions between magnetic, electronic, and structural degrees of freedom. In recent years, the discovery of a charge density wave (CDW) in the AV$_3$Sb$_5$ superconductors and structurally-derived bond density waves in FeGe and ScV$_6$Sn$_6$ have stoked the search for new kagome platforms broadly exhibiting density wave (DW) transitions. In this work, we evaluate the known AM$_6$X$_6$ chemistries and construct a stability diagram that summarizes the structural relationships between the $\approx$125 member family. Subsequently we introduce our discovery of the broader LnNb$_6$Sn$_6$ (Ln:Ce-Nd,Sm,Gd-Tm,Lu,Y) family of kagome metals and an analogous DW transition in LuNb$_6$Sn$_6$. Our X-ray scattering measurements clearly indicate a (1/3, 1/3, 1/3) ordering wave vector ($\sqrt{3}\times\sqrt{3}\times3$ superlattice) and diffuse scattering on half-integer $L$-planes. Our analysis of the structural data supports the ``rattling mode'' DW model proposed for ScV$_6$Sn$_6$ and paints a detailed picture of the steric interactions between the rare-earth filler element and the host Nb-Sn kagome scaffolding. We also provide a broad survey of the magnetic properties within the HfFe$_6$Ge$_6$-type LnNb$_6$Sn$_6$ members, revealing a number of complex antiferromagnetic and metamagnetic transitions throughout the family. This work integrates our new LnNb$_6$Sn$_6$ series of compounds into the broader AM$_6$X$_6$ family, providing new material platforms and forging a new route forward at the frontier of kagome metal research.

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Brenden R. Ortiz, William R. Meier, Ganesh Pokharel, Juan Chamorro, Fazhi Yang, Shirin Mozaffari, Alex Thaler, Steven J. Gomez Alvarado, Heda Zhang, David S. Parker, German D. Samolyuk, Joseph A. M. Paddison, Jiaqiang Yan, Feng Ye, Suchismita Sarker, Stephen D. Wilson, Hu Miao, David Mandrus, Michael A. McGuire. 2024-11-16. Stability frontiers in the AM$_6$X$_6$ kagome metals: The LnNb$_6$Sn$_6$ (Ln:Ce-Lu,Y) family and density-wave transition in LuNb$_6$Sn$_6$. https://doi.org/10.1021/jacs.4c16347

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