2018/05/24 by Wong, Chi Ho, Lortz, Rolf
#FOS: Physical sciences #Superconductivity (cond-mat.supr-con)
paper · doi:10.48550/arxiv.1805.09754
We present a theoretical ab-initio approach that allows us to explicitly calculate the superconducting transition temperatures (Tc) of the iron-based superconductors of LaFeAsO1-xFx, SmFeAsO1-xFx, NdFeAsO1-xFx, Ba1-xKxFe2As2, FeSe and LiFeAs that fit perfectly with the experiments. We consider recent evidence that electron-phonon coupling may have been underestimated previously, and a prediction that antiferromagnetism can greatly enhance electron-phonon coupling through localized iron d orbitals. We then include the contribution of these localized orbitals in a McMillan formalism. In addition, we take into account the spin-lattice interaction between the spin-polarized electrons at the Fermi surface and the iron orbitals in combination with a modified exchange Hamiltonian involving a ferrimagnetic coupling between Fe and As. With this approach we can accurately calculate the Tc of FeSe (11 family), LiFeAs (111 family), LaFeAsO0.9F0.1 (1111 family) and BaFe2As2 (122 family) as a function of pressure. In addition, we also obtain the correct doping dependence of Tc of LaFeAsO0.9F0.1 (1111 family) and BaFe2As2 (122 family).