Double-Q spin-density wave in iron arsenide superconductors

Allred, Jared M.; Taddei, Keith M.; Bugaris, Daniel E.; Krogstad, Matthew; Lapidus, Saul H.; Chung, Duck Young; Claus, H.; Kanatzidis, Mercouri G.; Brown, Dennis E.; Kang, Jian; Fernandes, Rafael M.; Eremin, I.; Rosenkranz, S.; Chmaissem, O.; Osborn, R.

doi:10.1038/nphys3629

Cited by 130 publications

(161 citation statements)

References 46 publications

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“…Although the cuprates and iron pnictides appear very different from each other, e.g., in the properties of their parent materials, Fermi surface topology, forms of interactions, etc., they both exhibit strong phase competition. In fact, the active orbital physics in iron pnictides make the C 2 and C 4 competition more apparent in K-doped BaFe 2 AS 2 or Na-doped SrFe 2 AS 2 [80][81][82][83][84].…”

Section: Discussionmentioning

confidence: 99%

Phase competition and anomalous thermal evolution in high-temperature superconductors

Zhou

Yin

et al. 2017

Phys. Rev. B

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The interplay of competing orders is relevant to high-temperature superconductivity known to emerge upon suppression of a parent antiferromagnetic order typically via charge doping. How such interplay evolves at low temperature-in particular at what doping level the zero-temperature quantum critical point (QCP) is located-is still elusive because it is masked by the superconducting state. The QCP had long been believed to follow a smooth extrapolation of the characteristic temperature T * for the strange normal state well above the superconducting transition temperature. However, recently the T * within the superconducting dome was reported to unexpectedly exhibit back-bending likely in the cuprate Bi2Sr2CaCu2O 8+δ . Here we show that the original and revised phase diagrams can be understood in terms of weak and moderate competitions, respectively, between superconductivity and a pseudogap state such as d-density-wave or spin-density-wave, based on both Ginzburg-Landau theory and the realistic t-t ′ -t ′′ -J-V model for the cuprates. We further found that the calculated temperature and doping-level dependence of the quasiparticle spectral gap and Raman response qualitatively agrees with the experiments. In particular, the T * back-bending can provide a simple explanation of the observed anomalous two-step thermal evolution dominated by the superconducting gap and the pseudogap, respectively. Our results imply that the revised phase diagram is likely to take place in high-temperature superconductors.

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Section: Discussionmentioning

confidence: 99%

Phase competition and anomalous thermal evolution in high-temperature superconductors

Zhou

Yin

et al. 2017

Phys. Rev. B

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“…3c belongs to the B 1,M representation, while the conjugate phase, 3d, belongs to the A 2,M representation. It is perhaps interesting to note that a number of experiments have found evidence of the C 4 symmetric charge-spin density wave in hole doped Ba122 compounds [31][32][33][34][35][36] . The space group of BaFe 2 As 2 , and indeed the 122 family, is I4/mmm, which is symmorphic, and we have seen that P4/nmm becomes symmorphic upon inversion symmetry breaking, stabilizing the C 4 symmetric spin vortex crystal.…”

Section: Group Structurementioning

confidence: 99%

Stabilizing the spin vortex crystal phase in two-dimensional iron-based superconductors

2017

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We present an investigation of the magnetic structure for iron-based superconductors (FeSCs) when inversion symmetry is broken, such as in substrate-supported monolayers or in the presence of a c-axis electric field. We perform group-, mean-field-, and density-functional-theoretic analyses on a model system of monolayer iron selenide (FeSe) on a strontium titanate (SrTiO3(001)) substrate. Our group-and mean-field-theoretic calculations are more generally applicable to thin films of the rest of the 11 (e.g., FeSe) family of iron-based superconductors, as well as to thin films of the 111 (e.g., LiFeAs) and 1111 (e.g., LaOFeAs) families, as these all belong to the same space group. We find that in systems with a collinear antiferromagnetic phase in bulk, when inversion symmetry is broken the transition is instead into a "spin vortex crystal" phase, and that a further phase transition can occur at a lower temperature in some circumstances. The spin vortex crystal is a C4 symmetric magnetic phase which is related to this parent C2 symmetric collinear antiferromagnetic (stripe) phase which is ubiquitous among the iron-based superconductors.

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“…12,13 The C 4 phase has been observed in three members of the hole-doped '122' family so far: Ba 1−x Na x Fe 2 As 2 , Ba 1−x K x Fe 2 As 2 and most recently Sr 1−x Na x Fe 2 As 2 . [12][13][14] In these materials the typical suppression of the antiferromagnetically (AFM) ordered orthorhombic C 2 phase (so-called for the 2-fold rotation axis) upon doping is complicated by a re-entrant tetragonal (I4/mmm symmetry) magnetically re-orientated C 4 phase. This higher symmetry phase appears at temperatures (T r ) below the C 2 transition (T N ) and at compositions (x) less than or equal to the critical concentration (x c ) beyond which no ordered magnetism is observed.…”

Section: Introductionmentioning

confidence: 99%

Observation of the magnetic C4 phase in Ca1−xNaxFe2As2

et al. 2017

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Since its discovery in 2014 the magnetic tetragonal C4 phase has been identified in a growing number of hole-doped '122' Fe-based superconducting compounds. Exhibiting a unique double-Q magnetic structure and a strong competition with both superconducting and magnetic order parameters, the C4 phase and the conditions of its formation are of significant interest to understanding the fundamental mechanisms in these materials. Particularly, separating the importance of direct changes to the relative size of hole and electron pockets at the Fermi surface (achieved via charge doping) from the role of structural changes due to differences of ionic radii of dopants is useful to determine the underlying parameter which causes the C4 instability. Here, we report the discovery of the C4 phase in a fourth member of the hole-doped '122' materials Ca1−xNaxFe2As2 (0.20 ≤ x ≤ 0.50) as determined from neutron and X-ray powder diffraction studies. The maximum of the C4 dome is observed at x = 0.44 with a re-entrant temperature Tr= 52K and an extent of ∆x ∼ 0.07 in composition. It is observed that for a range of compositions within the C4 dome (0.40 ≤ x ≤ 0.42) there is a second re-entrance (Tr 2 < Tr) where the AFM-C2 phase is recovered -a feature previously only seen in Ba1−xKxFe2As2. A phase diagram is presented for Ca1−xNaxFe2As2 and compared to the other Na + -doped '122's' -A1−xNaxFe2As2 with A = Ba, Sr and Ca. The structural parameters for these three systems are compared and the importance of the 'chemical pressure' due to changing the A-site ion (A = Ba, Sr, Ca) is discussed.

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Double-Q spin-density wave in iron arsenide superconductors

Cited by 130 publications

References 46 publications

Phase competition and anomalous thermal evolution in high-temperature superconductors

Phase competition and anomalous thermal evolution in high-temperature superconductors

Stabilizing the spin vortex crystal phase in two-dimensional iron-based superconductors

Observation of the magnetic C4 phase in Ca1−xNaxFe2As2

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