Electronic structure of new oxygen-free 38-K superconductor Ba1−x K x Fe2As2 in comparison with BaFe2As2 from the first principles

Abstract

Based on first-principles FLAPW-GGA calculation, we have investigated electronic structure of newly discovered oxygen-free 38K superconductor Ba 1-x K x Fe 2 As 2 in comparison with parent phase -tetragonal ternary iron arsenide BaFe 2 As 2 . The density of states, magnetic properties, near-Fermi bands compositions, together with Sommerfeld coefficients γ and molar Pauli paramagnetic susceptibility χ are evaluated. The results allow us to classify these systems as quasi-two-dimensional ionic metals, where the conduction is strongly anisotropic, only happening on the (Fe-As) layers.

Electronic properties of novel 6 K superconductor LiFeP in comparison with LiFeAs from first principles calculations

“…Our results show that replacements in blocks [Pd(Ni) 2 Ge(As) 2 ] of the d metal atoms (Pd ↔ Ni) or p elements (Ge ↔ As) lead to anisotropic deformations of the crystal structure caused by strong anisotropy of inter-atomic bonds in "122' phases (see also [20,24]), but the type of such deformations will be quite different. Thus, going from SrPd 2 Ge 2 to SrNi 2 Ge 2 , i.e.…”

“…The superconductivity in all these systems is attributed to the [M 2 Pn 2 ] blocks which make a decisive contribution to the near-Fermi region of these materials, while the positively charged blocks (for example, [RO] δ+ or A δ+ ) serve as the so-called charge reservoirs, see [2][3][4][5][6][7][8][9]. In particular, a broad family of the mentioned "122" superconductors (SC's) with transition temperatures up to T C ~ 38K (see [2][3][4][5][10][11][12][13][14][15][16]) based on AFe 2 As 2 phases (A = Ca, Sr or Ba) was prepared by hole doping, i.e. by partial substitution of alkaline metals for alkaline earth metals; or by partial replacement of Fe (in [Fe 2 As 2 ] blocks) by other 3d transition metals as Mn, Co or Ni.…”

“…These materials, where magnetic metal (Fe) is completely replaced by the other 3d magnetic metal (Ni) or non-magnetic metals (Ru, Rh) arsenic is completely replaced by other pnictogen -phosphorus, belong to the above mentioned "122" family and are low-temperature SC's (T C ~ 0.3-3.0K), see [21][22][23][24].…”

Electronic structure of Fe-based superconductors

“…[20,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51] While these differ in detail a number of common features are present. Fig.…”

Fermi surface, structural and electronic properties of ThCr2Si2-type charge-balanced KFe2AsSe: A parent sy

“…The valence states occupy the energy interval from E F to -6 eV, where the states from -6 eV to -4 eV and from -4 eV to -2 eV are mainly of Se 4p and As 4p character, respectively, and are hybridized with Fe 3d states. The near-Fermi states are mainly of the Fe 3d type, 31,32 As the electronic bands near the Fermi surface are involved in the formation of the superconducting state, it is important to elucidate their nature. Figure 4 shows the nearFermi bands for KFe 2 AsSe (1 and 2).…”