Emergence of superconductivity at 45 K by lanthanum and phosphorus co-doping of CaFe2As2

Kudo, Kazuhiro; Iba, Keita; Takasuga, Masaya; Kitahama, Yutaka; Matsumura, Jun Ichi; Danura, Masataka; Nogami, Yasuyuki; Nohara, M.

doi:10.1038/srep01478

Cited by 62 publications

(72 citation statements)

References 31 publications

(86 reference statements)

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“…(The c-axis length is unchanged in the C 2 structure transition at x ∼ 0.) Similarly, high-T c (∼ 50K) superconductivity is realized near the "collapsed C 4 phase" in rare-earth doped CaFe 2 As 2 [19,20]. In (La,P) co-doped CaFe 2 As 2 , higher-T c state is realized near the anion-height instability, whereas it avoids the AFM phase as clearly shown in Ref.…”

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confidence: 61%

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High-TcSuperconductivity near the Anion Height Instability in Fe-Based Superconductors: Analysis ofLaFeAsO1−x
Onari
¹
,
Yamakawa
²
,
Kontani
³

2014
Phys. Rev. Lett.
70
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100
0
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confidence: 61%

“…In (La,P) co-doped CaFe 2 As 2 , higher-T c state is realized near the anion-height instability, whereas it avoids the AFM phase as clearly shown in Ref. [19,20]. These experiments strongly indicate that the anion-height instability is a key ingredient for higher-T c superconductivity of order 50K.…”

mentioning

confidence: 66%

High-TcSuperconductivity near the Anion Height Instability in Fe-Based Superconductors: Analysis ofLaFeAsO1−x
Onari
¹
,
Yamakawa
²
,
Kontani
³

2014
Phys. Rev. Lett.
70
10
100
0
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“…However, as mentioned above, many studies show that the high Tc value will decrease after an optimal doping value, which also can't happen in the case of interface superconductivity. In fact, through codoping of element P, Kudo et al [24] have largely improved the high-Tc superconducting properties. The diamagnetic signal becomes relatively visible, indicating a possibility of obtaining bulk high-Tc superconductivity.…”

Section: Superconductivity Originmentioning

confidence: 99%

“…SC origins that are exotic such as interface SC, cloverlike defects, and strain effect should be excluded. The 'intrinsic' origin is also supported by the achievement of relatively large diamagnetic signal via co-doping of element P [24] or Co [25]. Nevertheless, if the high-Tc is really intrinsic, is there any possible way to increase the SC volume fraction and further realize bulk SC?…”

Section: Introductionmentioning

confidence: 99%

Review on origin of the unusual high-Tc superconductivity in Ca1−xRExFe2As2 (RE = La, Ce, Pr, Nd)

Zhou¹,

Shi²

2015

Novel Superconducting Materials

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Review on origin of the unusual high-T c superconductivity in Ca 1−x RE x Fe 2 As 2 (RE = La, Ce, Pr, Nd) Abstract: Since the discovery of high temperature superconductivity in iron pnictides in 2008, many iron-based superconductors (IBSs) with various crystal structures have been exploited. Among them, superconductivity with the onset transition temperature Tc up to 49 K has been detected in rare earth element doped CaFe 2 As 2 system (CaRE122). The electron doping induced high Tc values clearly exceed the highest Tcs induced by both hole doping (~38 K) and chemical or physical pressure (~33 K) in the 122-type iron-based superconductors. The occurrence of high-Tc superconductivity in this unique system is quite strange in terms of the much lower Tc observed in the sister compounds bearing structural and chemical similarities. Though the high-Tc superconductivity in Ca 1−x RExFe 2 As 2 is of the non-bulk feature, its superconducting origin served as a most important question has attracted tremendous attentions ever since its discovery. In this review, we summarize the previous experimental results observed in this series of superconductors and list the possible key points that may be related to the understanding of the nature for the strange high-Tc superconductivity.

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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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Emergence of superconductivity at 45 K by lanthanum and phosphorus co-doping of CaFe2As2

Cited by 62 publications

References 31 publications

High-TcSuperconductivity near the Anion Height Instability in Fe-Based Superconductors: Analysis ofLaFeAsO1−x
Onari
¹
,
Yamakawa
²
,
Kontani
³

2014
Phys. Rev. Lett.
70
10
100
0
View full text Add to dashboard Cite

High-TcSuperconductivity near the Anion Height Instability in Fe-Based Superconductors: Analysis ofLaFeAsO1−x
Onari
¹
,
Yamakawa
²
,
Kontani
³

2014
Phys. Rev. Lett.
70
10
100
0
View full text Add to dashboard Cite

Review on origin of the unusual high-Tc superconductivity in Ca1−xRExFe2As2 (RE = La, Ce, Pr, Nd)

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

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Emergence of superconductivity at 45 K by lanthanum and phosphorus co-doping of CaFe2As2

Cited by 62 publications

References 31 publications

High-TcSuperconductivity near the Anion Height Instability in Fe-Based Superconductors: Analysis ofLaFeAsO1−xOnari1, Yamakawa2, Kontani3 2014Phys. Rev. Lett.70101000View full textAdd to dashboardCite

High-TcSuperconductivity near the Anion Height Instability in Fe-Based Superconductors: Analysis ofLaFeAsO1−xOnari1, Yamakawa2, Kontani3 2014Phys. Rev. Lett.70101000View full textAdd to dashboardCite

Review on origin of the unusual high-Tc superconductivity in Ca1−xRExFe2As2 (RE = La, Ce, Pr, Nd)

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

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High-TcSuperconductivity near the Anion Height Instability in Fe-Based Superconductors: Analysis ofLaFeAsO1−x
Onari
¹
,
Yamakawa
²
,
Kontani
³

2014
Phys. Rev. Lett.
70
10
100
0
View full text Add to dashboard Cite

High-TcSuperconductivity near the Anion Height Instability in Fe-Based Superconductors: Analysis ofLaFeAsO1−x
Onari
¹
,
Yamakawa
²
,
Kontani
³

2014
Phys. Rev. Lett.
70
10
100
0
View full text Add to dashboard Cite

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