title: Revealing an unusual transparent phase of superhard iron tetraboride under high pressure.
abstract: First principles-based electronic structure calculations of superhard iron tetraboride (FeB4) under high pressure have been undertaken in this study. Starting with a "conventional" superconducting phase of this material under high pressure leads to an unexpected phase transition toward a semiconducting one. This transition occurred at 53.7 GPa, and this pressure acts as a demarcation between two distinct crystal symmetries, metallic orthorhombic and semiconducting tetragonal phases, with Pnnm and I4₁/acd space groups, respectively. In this work, the electron-phonon coupling-derived superconducting T(c) has been determined up to 60 GPa and along with optical band gap variation with increasing pressure up to 300 GPa. The dynamic stability has been confirmed by phonon dispersion calculations throughout this study.
authors.affiliation: Center of Excellence in Forum for Theoretical Science, Department of Physics, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand;
authors.forename: Komsilp
authors.initials: K
authors.lastname: Kotmool
authors.affiliation: Condensed Matter Theory Group, Department of Physics and Astronomy, Uppsala University, S-75120 Uppsala, Sweden;
authors.forename: Thanayut
authors.initials: T
authors.lastname: Kaewmaraya
authors.affiliation: Condensed Matter Theory Group, Department of Physics and Astronomy, Uppsala University, S-75120 Uppsala, Sweden;
authors.forename: Sudip
authors.initials: S
authors.lastname: Chakraborty
authors.affiliation: Departamento de Física, Universidade Federal de Santa Maria, 97105-900 Santa Maria, Rio Grande do Sul, Brazil;
authors.forename: Jonas
authors.initials: J
authors.lastname: Anversa
authors.affiliation: Center of Excellence in Forum for Theoretical Science, Department of Physics, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand; Thailand Center of Excellence in Physics, Commission on Higher Education, Bangkok 10400, Thailand;
authors.forename: Thiti
authors.initials: T
authors.lastname: Bovornratanaraks
authors.affiliation: Condensed Matter Theory Group, Department of Physics and Astronomy, Uppsala University, S-75120 Uppsala, Sweden;
authors.forename: Wei
authors.initials: W
authors.lastname: Luo
authors.affiliation: Geophysical Laboratory, Carnegie Institution for Science, Washington, DC 20015;
authors.forename: Huiyang
authors.initials: H
authors.lastname: Gou
authors.affiliation: Departamento de Física, Universidade Federal de Santa Maria, 97105-900 Santa Maria, Rio Grande do Sul, Brazil;
authors.forename: Paulo Cesar
authors.initials: PC
authors.lastname: Piquini
authors.affiliation: Quantum Functional Semiconductor Research Center, Dongguk University, Chung gu, Seoul 100-715, Korea;
authors.forename: Tae Won
authors.initials: TW
authors.lastname: Kang
authors.affiliation: Geophysical Laboratory, Carnegie Institution for Science, Washington, DC 20015; Center for High Pressure Science and Technology Advanced Research, Shanghai 201203, People's Republic of China; and mao@gl.ciw.edu rajeev.ahuja@physics.uu.se.
authors.forename: Ho-kwang
authors.initials: HK
authors.lastname: Mao
authors.affiliation: Condensed Matter Theory Group, Department of Physics and Astronomy, Uppsala University, S-75120 Uppsala, Sweden; Quantum Functional Semiconductor Research Center, Dongguk University, Chung gu, Seoul 100-715, Korea; Applied Materials Physics, Department of Materials and Engineering, Royal Institute of Technology, S-100 44 Stockholm, Sweden mao@gl.ciw.edu rajeev.ahuja@physics.uu.se.
authors.forename: Rajeev
authors.initials: R
authors.lastname: Ahuja
keywords: first principle study; high pressure; metal–semiconductor phase transition; superconductivity; superhard material