Highly two-dimensional electronic structure and strong fermi-surface nesting of the iron-based superconductor Sr_2ScFePO_3: A first-principles study

摘要

We perform first-principles calculations for a newly discovered iron-based superconductor Sr_2ScFePO_3 whose blocking layer is a thick perovskite-based oxide (Sr_2ScO_3) and systematically compare its results with those of other typical iron-based superconductors. We find that the thick blocking layer (Sr_2ScO_3) gives alomost perfectly cylindrical hole and electron Fermi surfaces compared to other types whose Fermi surfaces wind along k_z-axis. This high two-dimensionality can bring about the best nesting condition between the Fermi surfaces. This explains why Sr_2ScFePO_3 exhibits an exceptionally high-T_c among non-arsenic iron-based superconductors and suggests a strategy to enhance the superconducting transition temperature.