Correlation-enhanced electron-phonon coupling and superconductivity in (Ba,K)SbO3 superconductors

The electronic structure, lattice dynamics, and electron-phonon coupling (EPC) of the recently discovered (Ba, K)SbO3 superconductors are investigated by first-principles calculations. The EPC of (Ba, K)SbO3 is significantly enhanced by considering nonlocal electronic correlation using the Heyd-Scuseria-Ernzerhof hybrid exchange-correlation functional (HSE06). The EPC strength lambda of Ba0.35K0.65SbO3 is strongly increased from 0.33 in local-density approximation calculations to 0.59 in HSE06 calculations, resulting in a superconducting transition temperature T T of about 14.9 K, which is in excellent agreement with experimental value of similar to 15 K. Our findings suggest (Ba, K)SbO3 are extraordinary conventional superconductors, where nonlocal electronic correlation expands the bandwidth, enhances the EPC, and boosts the T-c. Moreover, we find both lambda and T-c depend crucially on the K-doping level for (Ba, K)SbO3 and (Ba, K)BiO3 compounds. (Ba, K)SbO3 have stronger EPC strength and higher T-c than those of (Ba, K)BiO3 at the same K-doping level.

Automated summary

The electronic structure, lattice dynamics, and electron-phonon coupling of (Ba, K)SbO3 superconductors are investigated using first-principles calculations. The nonlocal electronic correlation greatly enhances the EPC strength, resulting in an increased superconducting transition temperature.