Chemical enhancement of superconductivity in LaRu3Si2 with mode-selective coupling between kagome phonons and flat bands
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| Main Authors: | , , , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866911120121397248 |
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| author | Misawa, Ryo Kriener, Markus Yamada, Rinsuke Nakano, Ryota Jovanovic, Milena Schoop, Leslie M. Hirschberger, Max |
| author_facet | Misawa, Ryo Kriener, Markus Yamada, Rinsuke Nakano, Ryota Jovanovic, Milena Schoop, Leslie M. Hirschberger, Max |
| contents | 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 LaRu$_3$(Si$_{1-x}$Ge$_x$)$_2$ 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 $T_\mathrm{c}$. 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-$4d_{x^2-y^2}$ 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 LaRu$_3$Si$_2$ by mode-selective coupling between specific kagome phonons and the Ru-$d_{x^2-y^2}$ orbitals. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2503_22477 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Chemical enhancement of superconductivity in LaRu3Si2 with mode-selective coupling between kagome phonons and flat bands Misawa, Ryo Kriener, Markus Yamada, Rinsuke Nakano, Ryota Jovanovic, Milena Schoop, Leslie M. Hirschberger, Max Superconductivity Materials Science Strongly Correlated Electrons 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 LaRu$_3$(Si$_{1-x}$Ge$_x$)$_2$ 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 $T_\mathrm{c}$. 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-$4d_{x^2-y^2}$ 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 LaRu$_3$Si$_2$ by mode-selective coupling between specific kagome phonons and the Ru-$d_{x^2-y^2}$ orbitals. |
| title | Chemical enhancement of superconductivity in LaRu3Si2 with mode-selective coupling between kagome phonons and flat bands |
| topic | Superconductivity Materials Science Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2503.22477 |