Superconductivity at 28.3 and 17.1 K in (Ca4Al2O6−y)(Fe2Pn2) (Pn=As and P)

Shirage, Parasharam M.; Kihou, Kunihiro; Lee, Chul‐Ho; Kitô, Hijiri; Eisaki, H.; Iyo, A.

doi:10.1063/1.3508957

Cited by 71 publications

(85 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…5 By contrast, MgTi-42622 with a nearly ideal FeAs 4 -tetrahedron possesses slightly worse FS nesting properties of than that of Al-42622, 30 but T c is higher than in Al-42622. This result suggests that AFM spin fluctuations are not only a unique parameter for enhancing T c .…”

Section: 24mentioning

confidence: 95%

“…This contrasts with the optimally electron-doped LaFeAsO with T c =28 K in which either the F-substitution or the O-deficiency changes both the electron-doping level and the lattice parameters. In another context, note that the normalstate property for x=0 differs from the case of the related 42622 compound Ca 4 Al 2 O 6 Fe 2 As 2 (denoted as Al-42622), 5 as shown in Fig. 3(a).…”

Section: 24mentioning

confidence: 99%

“…25 Ti 0.75 ) 3 O y Fe 2 As 2 2 and ∼ 37 K for Sr 4 V 2 O 6 Fe 2 As 2 (V-42622), 3 in which an interlayer distance between FePn layers (L) is longer than 13Å. [2][3][4][5] However, a ground state of undoped (FeAs) − layer and a relation with the onset of SC in the Fe-pnictides with thick perovskite blocks has not been identified sufficiently, although it is well known that the superconductivity (SC) in Fe-pnictide compounds emerges in close proximity to antiferromagnetism (AFM).…”

mentioning

confidence: 99%

See 2 more Smart Citations

Antiferromagnetic Order and Superconductivity in Sr₄(Mg_0.5-xTi_0.5+x)₂O₆Fe₂As₂ with Electron Doping: ⁷⁵As-NMR Study

et al. 2012

View full text Add to dashboard Cite

We report an 75 As-NMR study on iron (Fe)-based superconductors with thick perovskitetype blocking layers Sr4(Mg0.5−xTi0.5+x)2O6Fe2As2 with x=0 and 0.2. We have found that antiferromagnetic (AFM) order takes place when x=0, and superconductivity (SC) emerges below Tc=36 K when x=0.2. These results reveal that the Fe-pnictides with thick perovskitetype blocks also undergo an evolution from the AFM order to the SC by doping electron carriers into FeAs planes through the chemical substitution of Ti +4 ions for Mg +2 ions, analogous to the F-substitution in LaFeAsO compound. The reason why the Tc=36 K when x=0.2 being higher than the optimally electron-doped LaFeAsO with Tc=27 K relates to the fact that the local tetrahedron structure of FeAs4 is optimized for the onset of SC.

show abstract

Section: 24mentioning

confidence: 95%

Section: 24mentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Antiferromagnetic Order and Superconductivity in Sr₄(Mg_0.5-xTi_0.5+x)₂O₆Fe₂As₂ with Electron Doping: ⁷⁵As-NMR Study

et al. 2012

View full text Add to dashboard Cite

show abstract

“…[2][3][4][5][6][7][8][9][10][11][12][13][14] All of the iron pnictide superconductors identified so far consist of a common structural motif, i.e., Fe 2 As 2 layers that are alternately stacked with various kinds of spacer layers. Therefore, the central goal for realizing a higher T c has been finding a novel spacer layer that can suitably tune the electronic states of Fe 2 As 2 layers.…”

mentioning

confidence: 99%

Superconductivity in Ca_1-xLa_xFeAs₂: A Novel 112-Type Iron Pnictide with Arsenic Zigzag Bonds

et al. 2013

View full text Add to dashboard Cite

We report superconductivity in the novel 112-type iron-based compound Ca 1Àx La x FeAs 2 . Single-crystal X-ray diffraction analysis revealed that the compound crystallizes in a monoclinic structure (space group P2 1 ), in which Fe 2 As 2 layers alternate with Ca 2 As 2 spacer layers such that monovalent arsenic forms zigzag chains. Superconductivity with a transition temperature (T c ) of 34 K was observed for the x ¼ 0:1 sample, while the x ¼ 0:21 sample exhibited trace superconductivity at 45 K. First-principles band calculations demonstrated the presence of almost cylindrical Fermi surfaces, favorable for the high T c in La-doped CaFeAs 2 .KEYWORDS: iron-based superconductors, Ca-La-Fe-As, 112-type, CaFeAs 2Since the discovery of superconductivity with a transition temperature (T c ) of 26 K in LaFeAsO 1Àx F x , 1) there has been tremendous effort towards synthesizing novel iron pnictide superconductors. [2][3][4][5][6][7][8][9][10][11][12][13][14] All of the iron pnictide superconductors identified so far consist of a common structural motif, i.e., Fe 2 As 2 layers that are alternately stacked with various kinds of spacer layers. Therefore, the central goal for realizing a higher T c has been finding a novel spacer layer that can suitably tune the electronic states of Fe 2 As 2 layers.Recently, superconductivity has been discovered in Ca 10 (Pt n As 8 )(Fe 2Àx Pt x As 2 ) 5 , which consists of As-As dimers with a formal electron count of As 2À in the spacer layer. [15][16][17][18] Because of the 4p 3 electron configuration of elemental arsenic, arsenic can form various bonding structures: (i) Isolated arsenic with a formal electron count of As 3À . Examples include A 3 As (A ¼ Li, Na, and K) and iron-based superconductors. (ii) Dimerized As-As with a single bond. Its formal electron count is As 2À . Sr 2 As 2 and Ca 10 (Pt n As 8 )(Fe 2Àx Pt x As 2 ) 5 with As-As dimer bonds in the spacer layer can be categorized here. (iii) A one-dimensional chain connected by arsenic single bonds with a formal electron count of As À . This category includes KAs as an example. Realizing novel iron-based superconductors with spacer layers composed of complex bonding networks of arsenic such as (iii) has been a longstanding challenge: Shim et al. have theoretically proposed the hypothetical compound BaFeAs 2 (112-type) with spacer layers of the arsenic square network, and suggested that such compounds can be used to examine the role of charge and polarization fluctuations as well as the importance of two-dimensionality in the mechanism of superconductivity. 19) Although the 112-type iron pnictides AEFeAs 2 (AE ¼ Ca, Sr, Ba) have not yet been synthesized, the isostructural compounds RET As 2 (RE = rare-earth elements; T ¼ Cu, Ag, Au) have been studied intensively. 20,21) In this letter, we present a report on the novel 112-type iron-based superconductor Ca 1Àx La x FeAs 2 . Although pure CaFeAs 2 was not obtained, we found that the substitution of a small amount of La for Ca stabilizes the 112 phase. Thus, Ca 1Àx La x FeAs 2 ...

show abstract

“…[1,[4][5][6][7][8][9][10] Figure 1 shows the crystal structures of the latter type, Ca n+1 M n Fe 2 As 2 O 3n−1 (n = 3 and 4). The thick blocking layer composed of Ca n+1 M n O 3n−1 expands the distance between FeAs layers along the c axis, and this layer distance ranges from ∼ 15to25 A.…”

Section: Introductionmentioning

confidence: 99%

NMR investigation of the iron-based superconductors Ca4(Mg,Ti)3Fe2As
Tomita
¹
,
Kotegawa
²
,
Tao
³

et al. 2012
Phys. Rev. B

View full text Add to dashboard Cite

75 As and 45 Sc NMR measurements unravel the electronic state for Fe-based superconductors with perovskite-type blocking layers Ca4(Mg,Ti)3Fe2As2O8−y (T onset c = 47 K) and Ca5(Sc,Ti)4Fe2As2O11−y (T onset c = 41 K). In Ca5(Sc,Ti)4Fe2As2O11−y, the nuclear spin relaxation rate 1/T1 shows pseudogap behavior below ∼ 80 K, suggesting that the electronic state is similar to that of LaFeAs(O,F) system with moderate electron doping. The presence of the pseudogap behavior gives an interpretation that the hole-like band (so-called γ pocket) is located just below the Fermi level from the analogy to LaFeAs(O,F) system and the disappearance of the γ pocket yields the suppression of the low-energy spin fluctuations. On the other hand, in Ca4(Mg,Ti)3Fe2As2O8−y satisfying the structural optimal condition for higher Tc among the perovskite systems, the extrinsic contribution, which presumably originates in the Ti moment, is observed in 1/T1T ; however, the moderate temperature dependence of 1/T1T appears by its suppression under high magnetic field. In both systems, the high Tc of ∼ 40 K is realized in the absence of the strong development of the low-energy spin fluctuations. The present results reveal that the structural optimization does not induce the strong development of the low-energy spin fluctuations. If we consider that superconductivity is mediated by spin fluctuations, the structural optimization is conjectured to provide a benefit to the development of the high-energy spin fluctuations irrespective to the low-energy part.

show abstract

Superconductivity at 28.3 and 17.1 K in (Ca4Al2O6−y)(Fe2Pn2) (Pn=As and P)

Cited by 71 publications

References 25 publications

Antiferromagnetic Order and Superconductivity in Sr₄(Mg_0.5-xTi_0.5+x)₂O₆Fe₂As₂ with Electron Doping: ⁷⁵As-NMR Study

Antiferromagnetic Order and Superconductivity in Sr₄(Mg_0.5-xTi_0.5+x)₂O₆Fe₂As₂ with Electron Doping: ⁷⁵As-NMR Study

Superconductivity in Ca_1-xLa_xFeAs₂: A Novel 112-Type Iron Pnictide with Arsenic Zigzag Bonds

NMR investigation of the iron-based superconductors Ca4(Mg,Ti)3Fe2As
Tomita
¹
,
Kotegawa
²
,
Tao
³

et al. 2012
Phys. Rev. B

Contact Info

Product

Resources

About

Superconductivity at 28.3 and 17.1 K in (Ca4Al2O6−y)(Fe2Pn2) (Pn=As and P)

Cited by 71 publications

References 25 publications

Antiferromagnetic Order and Superconductivity in Sr4(Mg0.5-xTi0.5+x)2O6Fe2As2 with Electron Doping: 75As-NMR Study

Antiferromagnetic Order and Superconductivity in Sr4(Mg0.5-xTi0.5+x)2O6Fe2As2 with Electron Doping: 75As-NMR Study

Superconductivity in Ca1-xLaxFeAs2: A Novel 112-Type Iron Pnictide with Arsenic Zigzag Bonds

NMR investigation of the iron-based superconductors Ca4(Mg,Ti)3Fe2AsTomita1, Kotegawa2, Tao3 et al. 2012Phys. Rev. B

Contact Info

Product

Resources

About

Antiferromagnetic Order and Superconductivity in Sr₄(Mg_0.5-xTi_0.5+x)₂O₆Fe₂As₂ with Electron Doping: ⁷⁵As-NMR Study

Antiferromagnetic Order and Superconductivity in Sr₄(Mg_0.5-xTi_0.5+x)₂O₆Fe₂As₂ with Electron Doping: ⁷⁵As-NMR Study

Superconductivity in Ca_1-xLa_xFeAs₂: A Novel 112-Type Iron Pnictide with Arsenic Zigzag Bonds

NMR investigation of the iron-based superconductors Ca4(Mg,Ti)3Fe2As
Tomita
¹
,
Kotegawa
²
,
Tao
³

et al. 2012
Phys. Rev. B