Theoretical study on the origin of the lattice structure variation of in the iron based superconductors

The paper focuses on the theoretical studies regarding the correlation between the lattice structure, band structure, spin fluctuations, and T c in the iron-based superconductors. It is shown how the appearance and the disappearance of the pocket-like Fermi surfaces affect the spin fluctuations and superconductivity. Within the theoretical study described here, T c is optimized around the regular tetrahedron bond angle because the Fermi surface multiplicity tends to be maximized around that angle due to the good symmetry of the system. A possible guiding principle for obtaining higher T c materials is provided.