Frustrated charge order and cooperative distortions in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi mathvariant="normal">ScV</mml:mi><mml:mn>6</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">Sn</mml:mi><mml:mn>6</mml:mn></mml:msub></mml:math>
Ganesh Pokharel, Brenden R. Ortiz, Linus Kautzsch, Steven J. Gomez Alvarado, Krishnanand Mallayya, Guang Wu, Eun-Ah Kim, Jacob P. C. Ruff, Suchismita Sarker, Stephen D. Wilson
Abstract
Here we study the stability of charge order in the kagome metal ${\mathrm{ScV}}_{6}{\mathrm{Sn}}_{6}$. Synchrotron x-ray diffraction measurements reveal high-temperature, short-range charge correlations at the wave vectors along $\mathbf{q}=(\frac{1}{3},\frac{1}{3},\frac{1}{2})$ whose interlayer correlation lengths diverge upon cooling. At the charge order transition, this divergence is interrupted, and long-range order freezes in along $\mathbf{q}=(\frac{1}{3},\frac{1}{3},\frac{1}{3})$, as previously reported, while disorder enables the charge correlations to persist at the $\mathbf{q}=(\frac{1}{3},\frac{1}{3},\frac{1}{2})$ wave vector down to the lowest temperatures measured. Both short-range and long-range charge correlations seemingly arise from the same instability and both are rapidly quenched upon the introduction of larger Y ions onto the Sc sites. Our results validate the theoretical prediction of the primary lattice instability at $\mathbf{q}=(\frac{1}{3},\frac{1}{3},\frac{1}{2})$, and we present a heuristic picture for viewing the frustration of charge order in this compound.