AUTHOR=Yu Rong , Hu Haoyu , Nica Emilian M. , Zhu Jian-Xin , Si Qimiao 

TITLE=Orbital Selectivity in Electron Correlations and Superconducting Pairing of Iron-Based Superconductors

JOURNAL=Frontiers in Physics

VOLUME=9

YEAR=2021

URL=https://www.frontiersin.org/journals/physics/articles/10.3389/fphy.2021.578347

DOI=10.3389/fphy.2021.578347

ISSN=2296-424X

ABSTRACT=<p>Electron correlations play a central role in iron-based superconductors. In these systems, multiple Fe <inline-formula id="inf1"><mml:math id="minf1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>3</mml:mn><mml:mi>d</mml:mi></mml:mrow></mml:math></inline-formula>-orbitals are active in the low-energy physics, and they are not all degenerate. For these reasons, the role of orbital-selective correlations has been an active topic in the study of the iron-based systems. In this article, we survey the recent developments on the subject. For the normal state, we emphasize the orbital-selective Mott physics that has been extensively studied, especially in the iron chalcogenides, in the case of electron filling <inline-formula id="inf2"><mml:math id="minf2" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>n</mml:mi><mml:mo>∼</mml:mo><mml:mn>6</mml:mn></mml:mrow></mml:math></inline-formula>. In addition, the interplay between orbital selectivity and electronic nematicity is addressed. For the superconducting state, we summarize the initial ideas for orbital-selective pairing and discuss the recent explosive activities along this direction. We close with some perspectives on several emerging topics. These include the evolution of the orbital-selective correlations, magnetic and nematic orders, and superconductivity as the electron filling factor is reduced from 6 to 5, as well as the interplay between electron correlations and topological band structure in iron-based superconductors.</p>