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arXiv · 2407.02654

Pairing interaction from Demons in Sr$_2$RuO$_4$

Young Woo Choi·Jisoon Ihm·Marvin L. Cohen
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Abstract

We investigate the properties of the recently observed "demon" mode, a 3D acoustic plasmon, in Sr$_2$RuO$_4$ with an emphasis on evaluating its role for the pairing interactions in this superconductor. The demon mode is a low-energy electronic excitation, and it has been suggested that it could contribute to a reduced Coulomb repulsion and even a possible attractive interaction between electrons. In this study, we explicitly calculate the dynamically screened Coulomb interaction for Sr$_2$RuO$_4$ by using a renormalized tight-binding band structure and the random phase approximation for the dielectric function. Although the focus here is on Sr$_2$RuO$_4$, this material is considered mainly as a prototype system, having an observed demon mode, and our results should be considered as a guide for application to other systems. Our calculations show that there are regions in ($\mathbf{q}$, $ω$) space where the Coulomb interaction becomes attractive. We find that, although the demon mode is not capable of producing a total attractive electron pairing interaction in Sr$_2$RuO$_4$, it does contribute to a significant reduction in the Coulomb repulsion at the relevant pairing energy scale.

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Young Woo Choi, Jisoon Ihm, Marvin L. Cohen. 2024-07-02. Pairing interaction from Demons in Sr$_2$RuO$_4$. https://arxiv.org/abs/2407.02654

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