Physical Review Materials

Charge density waves in kagome metals are typically identified through long-range structural order, yet their fluctuating counterparts may play an equally important role in shaping electronic phases. Using ultrafast coherent phonon spectroscopy, the authors reveal that in hole-doped CsV₃Sb₅, strong charge density wave fluctuations persist far beyond the disappearance of static order, with picosecond correlation times. These fluctuations peak near a doping-tuned quantum phase transition that coincides with a minimum in the superconducting double dome. Their results establish fluctuating charge order as a robust and ubiquitous feature of kagome metals and highlight its potential influence on superconductivity and other emergent quantum phenomena.

Kagome materials, with their corner-sharing triangular lattice, have attracted strong interest due to the interplay of correlations, magnetism, symmetry, and topology. Here, the authors engineer the magnetic landscape of ScMn${}_6$Sn${}_6$ via Ga doping to realize ScMn${}_6$(Sn${}_{0.78}$Ga${}_{0.22}$)${}_6$, which exhibits robust ferromagnetism below 375 K with an in-plane easy axis. High-resolution angle-resolved photoemission spectroscopy (ARPES) measurements reveal a Dirac cone near the Fermi energy, while theoretical calculations show that its gap can be tuned by the orientation of the magnetic moments. Additionally, a flat band spanning a large region of the Brillouin zone, originating from the Kagome lattice, is observed.

The kagome lattice has long attracted interest because its geometric frustration can give rise to unusual quantum states. When this lattice is distorted into a twisted or buckled arrangement, the resulting magnetic and electronic behavior becomes even richer. In this work, the authors synthesize and characterize single crystals of ErPdPb, a twisted kagome antiferromagnet in which the Er atoms form a frustrated magnetic network within the noncentrosymmetric ZrNiAl-type structure. Below 2.7 K, ErPdPb enters a strongly anisotropic magnetic state marked by fractional magnetization plateaus, competing exchange interactions, and pronounced directional dependence in its electronic properties. First-principles calculations in the field-polarized ferromagnetic state further reveal a spin-split saddle point close to the Fermi level and a quasi-one-dimensional Fermi surface. Together, these findings identify ErPdPb as a promising platform for investigating the interplay of magnetic frustration, electronic anisotropy, and topological band structure.

Antiferromagnetic kagome metals remain far less explored than their ferromagnetic counterparts, despite predictions of unconventional spin textures and emergent transport phenomena. Here, the authors report the growth of single crystals of the metallic kagome antiferromagnet CrRhAs and investigate its magnetic and electronic properties. While no nonlinear Hall effect is observed, Hall measurements reveal an unexpected sign reversal upon changing the current direction, together with a pronounced enhancement below the antiferromagnetic transition. These findings point to a strong coupling between magnetic order and an anisotropic electronic structure, highlighting CrRhAs as a promising platform for exploring transport phenomena in antiferromagnetic kagome metals.

Nematicity in kagome metals $A$V${}_3$Sb${}_5$ ($A$ = K, Rb, Cs) has been widely regarded as an electronically driven phenomenon. Here, the authors uncover a structural origin of nematic behavior in the CDW phase of RbV${}_3$Sb${}_5$ through firstprinciples calculations. They show that an interlayer $\pi$ phase shift induces anisotropic V–V bond reconstruction, forming a bond-order wave that breaks C${}_6$ rotational symmetry and gives rise to intrinsic C${}_2$ anisotropy. This bond-order mechanism manifests in distinctive signatures across the electronic structure, Fermi surface, phonon spectrum, and transport properties, establishing a unified microscopic framework for lattice-driven nematicity in kagome quantum materials.

Co substitution in the kagome magnet TbFe${}_{6-x}$Co${}_x$Ge${}_6$ drives a remarkable evolution of both crystal structure and magnetic behavior. Through combined diffraction and magnetization studies, the series transitions from an ordered orthorhombic phase to a hexagonal Yb${}_{0.5}$Co${}_3$Ge${}_3$-type structure as Co content increases. The gradual disappearance of superstructure reflections reveals suppression of short-range structural order, while magnetic measurements demonstrate significant modification of transition-metal sublattice magnetism. These results establish chemical substitution as an effective route for tuning the interplay between structural ordering and magnetic interactions in rare-earth kagome materials, providing new insight into composition-driven phase evolution.