2025/03/28 by Misawa, Ryo, Kriener, Markus, Yamada, Rinsuke +4 · 2 citations
#FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Strongly Correlated Electrons (cond-mat.str-el) #Superconductivity (cond-mat.supr-con)
paper · doi:10.48550/arxiv.2503.22477
In kagome metals, flat electronic bands induced by frustrated hopping are a platform for strong electron correlations. In particular, a selective coupling of flat band states to certain kagome phonon modes is proposed as a universal origin of superconductivity in this material class. Here, we investigate the superconductivity in the kagome system LaRu3(Si1-xGex)2 by chemical pressure tuning while preserving the Ru-4d states that constitute the kagome flat bands. We observe a sizable enhancement in the density of states up to x = 0.07, as determined by the specific heat, with a concomitant increase in the superconducting transition temperature Tc. Ge-dopants induce a uniaxial lattice expansion along the c-axis. Our first-principles calculations suggest that this mitigates the detrimental effect of hybridization between kagome layers and reduces the dispersion of the Ru-4dx2-y2 flat band. The calculated chemical potential moves closer to the maximum in the energy-dependent density of states. Our result is consistent with a theoretical prediction of tunable flat band superconductivity in LaRu3Si2 by mode-selective coupling between specific kagome phonons and the Ru-dx2-y2 orbitals.