Why $T_c$ of (CaFeAs)$_{10}$Pt$_{3.58}$As$_8$ is twice as high as (CaFe$_{0.95}$Pt$_{0.05}$As)$_{10}$Pt$_3$As$_8$

TL;DR

This study compares the electronic structures of two similar superconductors, revealing that differences in their Fermi surface details and band-edge singularities significantly influence their critical temperatures.

Contribution

The paper provides the first detailed ARPES comparison of these compounds, emphasizing the impact of Fermiology on superconducting transition temperatures.

Findings

Significant differences in electronic structure between the two compounds.

Fermi surface details and band-edge singularities correlate with $T_c$ differences.

Highlights the importance of electronic structure in high-$T_c$ superconductivity.

Abstract

Recently discovered (CaFe$_{1-x}$Pt$_x$As)$_{10}$Pt$_3$As$_8$ and (CaFeAs)$_{10}$Pt$_{4-y}$As$_8$ superconductors are very similar materials having the same elemental composition and structurally similar superconducting FeAs slabs. Yet the maximal critical temperature achieved by changing Pt concentration is approximately twice higher in the latter. Using angle-resolved photoemission spectroscopy(ARPES) we compare the electronic structure of their optimally doped compounds and find drastic differences. Our results highlight the sensitivity of critical temperature to the details of fermiology and point to the decisive role of band-edge singularities in the mechanism of high-$T_c$ superconductivity.