Superconducting gap symmetry of strained Sr$_2$RuO$_4$

The superconducting gap symmetry of Sr$_2$RuO$_4$ is still under debate. Even though many experimental evidences suggest a chiral p-wave symmetry, others would rather support a d-wave symmetry\footnote{E. Hassinger \textit{and al}, arXiv:1606.04936}. Recently, it was shown that the uniaxial or biaxial strain can be employed to induce a Lifshitz transition in this compound. The ARPES results of the strained Sr$_2$RuO$_4$ have shown that the Fermi level could be brought very close to van Hove singularities, leading to a change in the Fermi surface topology and strong variations of the quasi-particule mass enhancement\footnote{Y. Hsu \textit{and al}, Phys. Rev. B \textbf{94}, 045118 (2016)}$^{,}$\footnote{B. Burganov \textit{and al}, Phys. Rev. Lett. \textbf{116}, 197003 (2016)}. Such a drastic change in the electronic structure of the system should influence the competition between different pairing symmetries. In our study, we used DFT+DMFT calculation to investigate the effect of strain on the spin excitation spectra of Sr$_2$RuO$_4$ and in turn the spin fluctuation mediated pairing interaction.