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The Effects of Pressure on the Structural, Electronic, and Lattice Dynamical Properties of FeSe Superconductor

Authors
  • Lu, Hong-Yan1
  • Wang, Ni-Na1
  • Wei, Meng-Jun1
  • Chen, San1
  • Yang, Yang2
  • Shao, Ding-Fu3
  • Lu, Wen-Jian3
  • 1 Huaibei Normal University, School of Physics and Electronic Information, Huaibei, 235000, China , Huaibei (China)
  • 2 Zhengzhou University of Light Industry, College of Physics and Electronic Engineering, Zhengzhou, 450002, China , Zhengzhou (China)
  • 3 Chinese Academy of Sciences, Key Laboratory of Materials Physics, Institute of Solid State Physics, Hefei, 230031, China , Hefei (China)
Type
Published Article
Journal
Journal of Low Temperature Physics
Publisher
Springer US
Publication Date
Dec 02, 2014
Volume
178
Issue
5-6
Pages
355–366
Identifiers
DOI: 10.1007/s10909-014-1253-y
Source
Springer Nature
Keywords
License
Yellow

Abstract

Motivated by the experimental huge enhancement of the superconducting transition temperature Tc\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$T_\mathrm{c}$$\end{document} in FeSe superconductor under high pressure, we perform first-principles calculations of the evolutions of structural, electronic, and lattice dynamical properties of FeSe at varying hydrostatic pressures up to 8 GPa. The pressure response is anisotropic with a larger compressibility along c\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$c$$\end{document}-axis. At ambient pressure, Fermi surface nesting between hole and electron pockets induces spin density wave (SDW) order at the vector (π\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\pi $$\end{document}, π\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\pi $$\end{document}, 0) with a collinear antiferromagnetic structure. With the increase of pressure, the Fermi surface nesting is reduced, and therefore the SDW is suppressed, which could not enhance superconductivity based on the spin-fluctuation scenario. For the phonon dispersion, the bands have blue-shift except for the modes around 100 cm-1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{-1}$$\end{document}, indicating hardening of the vibration modes in a wide frequency range. Furthermore, the electron–phonon coupling constant and the corresponding Tc\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$T_\mathrm{c}$$\end{document} by McMillan equation are calculated. However, there is no obvious enhancement of Tc\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$T_\mathrm{c}$$\end{document} under pressure, which further rules out the conventional phonon-mediated superconductivity of FeSe. Maybe the local magnetic moment plays an important role for the superconductivity and enhancement of Tc\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$T_\mathrm{c}$$\end{document} under pressure.

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