Electronic structure and phonon spectrum of binary iron-based superconductor FeSe in both nonmagnetic and striped antiferromagnetic phases

Abstract

Using first-principles calculations, we investigate electronic structure and phonon spectrum of binary iron-based superconductor FeSe in both tetragonal nonmagnetic (NM) phase and orthorhombic striped antiferromagnetic (SAF) phase. It is found that the softening of atomic vibration modes and main electron–phonon coupling contribution from low-frequency Eliashberg spectral function α 2 F ( ω ) in SAF phase of FeSe lead to the enhancement of electron–phonon coupling strength λ ep and logarithmically average frequency ω ln . However, the obtained superconducting T c in SAF phase just increases up to 0.34 K, even though Coulomb pseudopotential μ ∗ is limited to zero. As a result, our magnetic phonons calculation still rules out phonon mediated superconductivity, although the electron–phonon coupling through the spin channel play an important role in FeSe.