Renormalization in Raman spectral evolution through electron-phonon coupling in the correlated polar metal Ca₃Ru₂O₇

Polar metal Ca3Ru2O7 undergoes two transitions: 1) at 48K where the spins reorientation followed by the reconfiguration of electronic properties near Fermi surface drive the system from metallic to pseudo-gapped phase[1]; 2) at 30K where the Fermi surface is further reconstructed [2] and the thermal transport property drastically changes due to fermiology changes[3]. Here we demonstrate two phonon modes in Ca3Ru2O7 strongly correlated with electronic states near Fermi level and are sensitive to Fermi surface reconstruction. First principal calculation explained mode-specific e-ph constants of the two modes crossed-over at 48K. Besides, experimental evidence of phonon amplitude renormalization is found at 30K. Our result suggests Raman spectroscopy as a sensitive tool to fermiology changes in strong correlated systems.

 

[1] Markovic, I. et al. Electronically driven spin-reorientation transition of the correlated polar metal Ca3Ru2O7. P Natl Acad Sci USA 117, 15524-15529, doi:10.1073/pnas.2003671117 (2020).

[2] Horio, M. et al. Electronic reconstruction forming a C2-symmetric Dirac semimetal in Ca3Ru2O7. npj Quantum Materials 6, (2021).

[3] Xing, H. et al. Existence of electron and hole pockets and partial gap opening in the correlated semimetal Ca3Ru2O7. Physical Review B 97, (2018).