Critical role of magnetic moments in the lattice dynamics of YBa2Cu3O6

The role of lattice dynamics in unconventional high-temperature superconductivity is still vigorously debated. Theoretical insights into this problem have long been prevented by the absence of an accurate first-principles de-scription of the combined electronic, magnetic, and lattice degrees of freedom. Utilizing the recently constructed r2SCAN density functional that stabilizes the antiferromagnetic (AFM) state of the pristine oxide YBa2Cu3O6, we faithfully reproduce the experimental dispersion of key phonon modes. We further find significant magnetoe-lastic coupling in numerous high-energy Cu-O bond stretching optical branches, where the AFM results improve over the soft nonmagnetic phonon bands.

Automated summary

The role of lattice dynamics in unconventional high-temperature superconductivity is still debated, but has long been hindered by the lack of an accurate first-principles description of the combined electronic, magnetic, and lattice degrees of freedom. Using the r2SCAN density functional that stabilizes the antiferromagnetic state of YBa2Cu3O6, we accurately reproduce the experimental dispersion of key phonon modes and find significant magnetoe-lastic coupling in high-energy Cu-O bond stretching optical branches.