Extraordinary quasiparticle scattering and bandwidth-control by dopants in iron-based superconductors

TL;DR

This study reveals how dopants in iron-based superconductors uniquely influence quasiparticle scattering and bandwidth, providing a comprehensive microscopic understanding of their electronic effects and phase diagram diversities.

Contribution

It uncovers site and band dependencies of quasiparticle scattering and demonstrates significant bandwidth control by various dopants, advancing the understanding of doping effects in iron-based superconductors.

Findings

Doping affects quasiparticle scattering depending on site and band.

Bandwidth can be controlled by isovalent and heterovalent dopants.

Bandwidth control is achieved through chemical pressure or electron doping, not hole doping.

Abstract

The diversities in crystal structures and ways of doping result in extremely diversified phase diagrams for iron-based superconductors. With angle-resolved photoemission spectroscopy (ARPES), we have systematically studied the effects of chemical substitution on the electronic structure of various series of iron-based superconductors. In addition to the control of Fermi surface topology by heterovalent doping, we found two more extraordinary effects of doping: 1. the site and band dependencies of quasiparticle scattering; and more importantly 2. the ubiquitous and significant bandwidth-control by both isovalent and heterovalent dopants in the iron-anion layer. Moreover, we found that the bandwidth-control could be achieved by either applying the chemical pressure or doping electrons, but not by doping holes. Together with other findings provided here, these results complete the microscopic picture of the electronic effects of dopants, which facilitates a unified understanding of the diversified phase diagrams and resolutions to many open issues of various iron-based superconductors.