Structural properties and superconductivity of SrFe₂As_{2 −x}P_x(0.0 ≤x≤ 1.0) and CaFe₂As_{2 −y}P_y(0.0 ≤y≤ 0.3)

Abstract

The SrFe(2)As(2 - x)P(x) (0.0 ≤ x ≤ 1.0) and CaFe(2)As(2 - y)P(y) (0.0 ≤ y ≤ 0.3) materials were prepared by a solid-state reaction method. X-ray diffraction measurements indicate that the single-phase samples can be successfully obtained for SrFe(2)As(2 - x)P(x) (0.0 ≤ x ≤ 0.8) and CaFe(2)As(2 - y)P(y) (0.0 ≤ y ≤ 0.3). Visible contraction of the lattice parameters is determined due to the relatively smaller radius of P ions in comparison with that of As. The spin-density-wave (SDW) instability associated with the tetragonal to orthorhombic phase transition is suppressed noticeably in both systems following the increase in P content. The highest superconducting transitions are observed at about 27 K in SrFe(2)As(1.3)P(0.7) and at about 13 K in CaFe(2)As(1.925)P(0.075), respectively. Structural analysis suggests that lattice contraction could notably affect the superconductivity in these materials.

NMR evidence for an intimate relationship between antiferromagnetic spin fluctuations and extendeds-wave superconductivity in monocrystallineSrFe2(As1−xMiyamoto1, Mukuda2, Kobayashi3 et al. 2015Phys. Rev. B13260View full textAdd to dashboardCite

“…4,8 Note that the lattice parameter along the c-axis in Sr122AsP is smaller than that in Ba122AsP due to the ion radius smaller for Sr than for Ba, giving rise to a significant deformation in the Fermi surface topologies. 21 Nevertheless the phase diagram of AFM and SC phases in Sr122AsP 14,16 resembles that in Ba122AsP.…”

Quantum oscillation studies of the Fermi surface of iron-pnictide superconductors

“…Unlike the corresponding arsenides, the Fermi surfaces of the phosphides are very similar to those of the superconducting phases of the Ba and Sr 122 materials. In all three (Ba, Sr, Ca) phosphides superconductivity can be induced by partial substitution of P with isovalent As [32,33] and hence the pure phosphide can be viewed as the end member of these series. The maximum T c produced by P/As substitution is very comparable to that obtained by the non-isovalent dopants K [11] / Co [34] or pressure [35].…”

Ferromagnetism and superconductivity in CeFeAs1−xPxO (Jesche1, Förster2, Spehling3 et al. 2012Phys. Rev. B

“…This is a very general property of the Fe-based superconductors and in fact there are only a few examples known where SC does not show up despite vanishing Fe ordering [e.g., Mn-doped LaFeAsO 7 or BaFe 2 As 2 8 ]. In this sense CeFeAs 1−x P x O presents a unique situation because of the following: First, replacing As with P "usually" results in SC as shown for AFe 2 As 2 [A = Ca, 9 Ba, 10 Sr, 9 Eu 11 ] and RFeAsO [R = La, 5 Sm 12 ], and second, CeFeAsO becomes superconducting when substituting Fe with Co 13 or O with F 14 and also by inducing oxygen vacancies. 2 But combining P doping with R = Ce among the RFeAsO compounds results in exceptional behavior: The Fe ordering is suppressed, as shown by de la Cruz et al 15 and Luo et al, 16 however, superconductivity had not yet been observed in CeFeAs 1−x P x O.…”