2017/08/24 by Thiago X. R. Souza, F. Marsiglio
Physics and Astronomy · #BCS theory #Coupling (piping) #Crossover #Gravitational singularity #Limit (mathematics) #Physics of Superconductivity and Magnetism #Quantum, superfluid, helium dynamics #Singularity #Superconductivity #Superconductivity in MgB2 and Alloys #Van Hove singularity #cond-mat.supr-con
paper · pdf · doi:10.1142/s0217979217450035
published as International Journal of Modern Physics B, Vol. 31, 1745003-1-9 (2017) · 5 pages 2 figures
arxiv created 2017/08/24 · openalex publication_date 2017/08/28 · openalex created_date 2017/08/31 · arxiv updated 2018/01/09 · openalex updated_date 2026/08/05
We observe that H 3 S has a BCC structure and, with nearest neighbor hopping only, a strong singularity occurs at zero energy. This singularity is accompanied with a highly nested Fermi surface, which is not conducive to a stable superconducting instability. Introduction of next-nearest-neighbor hopping removes the singularity, but a “robust” peak remains in the electron density of states. Solution of the BCS equations shows an enhanced superconducting [Formula: see text] due to this peak. Furthermore, nesting is no longer present, so other instabilities will not compete effectively with superconductivity. We find high critical temperatures are possible, even with very modest coupling strengths. We also examine a limit of the [Formula: see text] equations (in an Appendix) where an analytical solution is possible over the entire range of coupling strengths, and therefore the BCS-BEC crossover is fully covered.