Bond-density-wave orders induced by geometric frustration in the kagome metal CeRu3Si2

TL;DR

This paper reports the discovery of bond-density-wave orders in the kagome metal CeRu3Si2, induced by geometric frustration, revealing a new pathway for frustration physics involving chemical bonding at above-room temperatures.

Contribution

It demonstrates that chemical bonding in kagome metals can host complex bond-ordered states driven by geometric frustration, expanding the understanding of emergent phases in quantum materials.

Findings

Observation of two distinct long-period superlattices with structural modulations.

Interlayer bonds modulate in a sublattice-selective manner to satisfy zero-sum constraint.

Bond-density-wave orders are induced by geometric frustration in CeRu3Si2.

Abstract

Geometric frustration gives rise to vast manifolds of degenerate ground states and competing orders in spin and charge systems. Typically, classical ground states are governed by a local ``zero-sum constraint" that relieves frustrated antiferromagnetic interactions or Coulomb repulsion. To date, the paradigm of geometric frustration has yielded a rich landscape of emergent phases, from spin ices and quantum spin liquids to charge glasses. However, an analogous phase rooted in chemical bonding has yet to be firmly demonstrated. Here we report the discovery of bond-density-wave orders induced by geometric frustration in the kagome metal CeRu$_3$Si$_2$ above room temperature. Through synchrotron X-ray diffraction, real-space transmission electron microscopy, and model calculations, we observe two distinct long-period superlattices with harmonic and anharmonic structural modulations. Crucially, interlayer bonds between kagome planes modulate in a sublattice-selective manner to fulfill the zero-sum constraint on the kagome lattice. We demonstrate the potential of kagome metals to host complex bond-ordered states constrained by geometric frustration and establish chemical bonding as a distinct pathway to frustration physics in quantum materials even above room temperature.