Superconductivity of KFe2As2 Under Pressure: Ab Initio Study of Tetragonal and Collapsed Tetragonal Phases

Abstract

KFe2As2 is one of the representatives of iron-based superconductors. Many interesting features distinguish this compound from other iron-based superconductors, e.g., a realization of the Pauli limit or an occurrence of the superconducting gap with nodal lines. Moreover, with increasing pressure, the isostructural phase transition from the tetragonal to collapsed tetragonal phase is experimentally observed. We discuss the structural, electronic, and superconducting properties of the KFe2As2 under pressure using the ab initio density functional theory (DFT) methods. We analyze the untypical properties of this superconductor considering, among others, the Fermi surfaces or the dependence of the anion height from the iron layer on the superconducting critical temperature.

Superconductivity in Quantum Complex Matter: the Superstripes Landscape

“…At Superstripes 2019 conference Torsello et al [83], Pal et al [84] and Ptok et al [85] presented the most recent investigations on the gap anisotropy in multigap superconductivity and the effect of pressure in iron based superconductors.…”

Sign change in c-axis thermal expansion constant and lattice collapse by Ni substitution in transition-metal zirconide superconductor Co1−xNixZr2

“…We propose that the change in the c/a ratio as shown in Fig. 5c is a kind of transition to collapsed tetragonal phases as observed in iron-based superconductors CaFe 2 As 2 and KFe 2 As 2 and related layered compound [26][27][28][29][30] . The electronic structure is generally affected by a collapsed tetragonal transition, which affects superconductivity as well 31,32 , we assume that the disappearance of bulk superconductivity by Ni heavy doping is related to the collapsed transition.…”