Correlation-enhanced electron-phonon coupling and superconductivity in (Ba ,K ) Sb O3 superconductors
The electronic structure, lattice dynamics, and electron-phonon coupling (EPC) of the recently discovered (Ba ,K ) Sb O3 superconductors are investigated by first-principles calculations. The EPC of (Ba ,K ) Sb O3 is significantly enhanced by considering nonlocal electronic correlation using the Heyd-Scuseria-Ernzerhof hybrid exchange-correlation functional (HSE06). The EPC strength λ 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 Tc of about 14.9 K, which is in excellent agreement with experimental value of ∼15 K. Our findings suggest (Ba ,K ) Sb O3 are extraordinary conventional superconductors, where nonlocal electronic correlation expands the bandwidth, enhances the EPC, and boosts the Tc. Moreover, we find both λ and Tc depend crucially on the K-doping level for (Ba ,K ) Sb O3 and (Ba ,K ) Bi O3 compounds. (Ba ,K ) Sb O3 have stronger EPC strength and higher Tc than those of (Ba ,K ) Bi O3 at the same K-doping level.
Physical Review B
- Pub Date:
- January 2022
- Condensed Matter - Superconductivity;
- Physics - Computational Physics
- 29 pages, 10 figures