New iron-based arsenide oxides (Fe2As2)(Sr4M2O6)(M = Sc, Cr)

Ogino, Hiroshi; Katsura, Yukari; Horii, Shigeru; Kishio, K.; Shimoyama, Jun–ichi

doi:10.1088/0953-2048/22/8/085001

Cited by 85 publications

(89 citation statements)

References 25 publications

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“…14) is still controversial. Findings from 57 Fe-Mössbauer spectroscopy gave evidence of homogeneous co-existence, while 75 As-NMR [106] and mSR [107] data indicated mesoscopic phase separation in magnetic and superconducting fractions. On the other hand, homogeneous co-existence is generally accepted in the Co-doped system Ba(Fe 1Àx Co x ) 2 As 2 [108] (see below).…”

Section: Structural Flexibilitymentioning

confidence: 98%

Structural chemistry of superconducting pnictides and pnictide oxides with layered structures

Johrendt

Hosono

Hoffmann

et al. 2011

Zeitschrift Für Kristallographie

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Abstract. The basic structural chemistry of superconducting pnictides and pnictide oxides is reviewed. Crystal chemical details of selected compounds and group subgroup schemes are discussed with respect to phase transitions upon charge-density formation, the ordering of vacancies, or the ordered displacements of oxygen atoms. Furthermore, the influences of doping and solid solutions on the valence electron concentration are discussed in order to highlight the structural and electronic flexibility of these materials.

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Section: Structural Flexibilitymentioning

confidence: 98%

Structural chemistry of superconducting pnictides and pnictide oxides with layered structures

Johrendt

Hosono

Hoffmann

et al. 2011

Zeitschrift Für Kristallographie

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“…Although many Fe-based compounds contain the perovskite-related layers, such as A 3 M 2 Fe 2 (As,P) 2 O 5 [16,19] and A 4 M 2 Fe 2 (As,P) 2 O 6 [20][21][22][23] (A = Ca, Sr, Ba, M = Sc, V, Cr), only 2 members Sr 4 Sc 2 Fe 2 P 2 O 6 [16] and Sr 4 V 2 Fe 2 As 2 O 6 [20] are superconducting (T c is 17 K and 37 K, respectively) as far as we know. It appears that progress of studies of the distant Fe 2 As 2 layered systems seems to be much behind that of the studies of the intensely coupled Fe 2 As 2 layered systems such as the doped LnFeAsO (Ln = rare-earth element) and AFe 2 As 2 (A = Ca, Sr, Ba).…”

Section: Introductionmentioning

confidence: 99%

“…synthesized under an ambient-pressure condition. The stoichiometric mixture of the powders was heated in a Ta capsule in an evacuated quartz tube at 1050 °C for 50 hr, as reported elsewhere [22].…”

Section: Introductionmentioning

confidence: 99%

Magnetic and electrical properties and carrier doping effects on the iron-based host compound Sr2ScFeAsO3

et al. 2011

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Additional charge carriers were introduced to the iron oxyarsenide Sr 4 Sc 2 Fe 2 As 2 O 6 under a high-pressure condition, followed by measurements of electrical resistivity, Hall coefficient, and magnetic susceptibility. The host compound Sr 4 Sc 2 Fe 2 As 2 O 6 shows metallic conductivity down to ~200 K and turns to show a semiconducting-like conductivity accompanied by a positive magneto-resistance (22% at 70 kOe). Although the carrier density is comparable at 300 K (5.9×10 21 cm -3 ) with that of the other Fe-based superconductors, no superconductivity appears down to 2 K. This is primarily because the net carrier density decreases over 3 orders of magnitude on cooling and additionally a possible magnetic order at ~120 K prevents carriers from pairing. The properties were altered largely by introducing the additional carriers.

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“…[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.…”

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confidence: 99%

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

et al. 2013

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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 ...

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New iron-based arsenide oxides (Fe₂As₂)(Sr₄M₂O₆)(M = Sc, Cr)

Cited by 85 publications

References 25 publications

Structural chemistry of superconducting pnictides and pnictide oxides with layered structures

Structural chemistry of superconducting pnictides and pnictide oxides with layered structures

Magnetic and electrical properties and carrier doping effects on the iron-based host compound Sr2ScFeAsO3

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

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New iron-based arsenide oxides (Fe2As2)(Sr4M2O6)(M = Sc, Cr)

Cited by 85 publications

References 25 publications

Structural chemistry of superconducting pnictides and pnictide oxides with layered structures

Structural chemistry of superconducting pnictides and pnictide oxides with layered structures

Magnetic and electrical properties and carrier doping effects on the iron-based host compound Sr2ScFeAsO3

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

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New iron-based arsenide oxides (Fe₂As₂)(Sr₄M₂O₆)(M = Sc, Cr)

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