Accurate lattice dynamics of cuprates from first principles*

The role lattice dynamics play in unconventional high-temperature superconductivity is unclear and is still vigorously debated. Theoretical insights into this problem have long been frustrated by the absence of an accurate first-principles description of the electronic, magnetic, and lattice degrees of freedom. Utilizing the recently constructed SCAN meta-GGA density functional [1] we find the calculated phonon dispersions of YBa₂Cu₃O₆ in excellent accord with experimental measurements. Moreover, we find the strong magnetoelastic coupling for key phonon modes to be crucial in reproducing the experimental results. The improved description of SCAN over PBE, LDA, and DFT+U, is attributed to the holistic picture SCAN provides, where charge, magnetism, and lattice dynamics are treated on the same footing [2]. This work paves the way for further studies on the coupling between quasiparticles in cuprates, which is vital for unveiling the secrets behind unconventional high temperature superconductivity.

[1] J. Sun, A. Ruzsinszky, J. P. Perdew, Physical Review Letters 115, 036402 (2015).
[2] Proceedings of the National Academy of Sciences, 117, 68 (2020).