Site-Selective Antimony Doping in Arsenic Zigzag Chains of 112-Type Ca1−xLaxFeAs2

Ota, Hiromi; Kudo, Kazuhiro; Kimura, T.; Kitahama, Yutaka; Mizukami, Tasuku; Ioka, Satoshi; Nohara, M.

doi:10.7566/jpsj.86.025002

Cited by 11 publications

(7 citation statements)

References 21 publications

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“…This sample exhibits as a metallic behavior in normal state. It was observed that by substitution of P in Nd-1111, the superconductivity state eliminates and the structural transition temperature appears at 140 K. The shape of the FeAs 4 tetrahedron seems to play a conclusive role with, in particular, the Fe-As bond length having a robust effect on the transition temperature superconductivity [35,53,20,24,22,54,12]. The bond length of Fe-As in the Nd-1111 sample is 0.2404 nm and it decreases by substitution of P/As and Sb/As.…”

Section: Resultsmentioning

confidence: 99%

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Isovalent Substitution Effects of Arsenic on Structural and Electrical Properties of Iron-Based Superconductor NdFeAsO0.8F0.2

Alborzi

Daadmehr

2019

J Supercond Nov Magn

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In this paper, nominal compositions of NdFeAsO 0.8 F 0.2 , NdFeAs 0.95 Sb 0.05 O 0.8 F 0.2 and NdFeAs 0.95 P 0.05 O 0.8 F 0.2 were prepared by one-step solid-state reaction method. The structural, electrical and morphological properties of samples were characterized through the XRD pattern, the 4-probe method and SEM, respectively. The crystal structure of our samples was tetragonal with P4/nmm:2 symmetry group. Also, the (x, y, z), occupancy of ions and lattice parameters were changed by isovalent substitution of Phosphorus (P) and Antimony (Sb)in the NdFeAsO 0.8 F 0.2 sample. The ⍺, β bond angles and Fe-As bond length are changed from the corresponding value of ⍺ and β regular FeAs4-tetrahedron by isovalent doping P/As and Sb/As, that they are effective on the superconductivity transition temperature. The microstrain and crystalline size of samples were studied by the Williamson Hall method. The superconducting critical temperatures were attained at 56 K and 46 K for NdFeAsO 0.8 F 0.2 , NdFeAs 0.95 Sb 0.05 O 0.8 F 0.2 , respectively. The NdFeAs 0.95 P 0.05 O 0.8 F 0.2 showed the structural transition temperature at 140 K. It seems that there is a relation between the superconductivity and shrinkage of the crystal lattice. The flake-type of grains was observed by SEM pictures of samples.

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Section: Resultsmentioning

confidence: 99%

“…1111type) [9][10][11]of course two other subgroups were introduced for this category of superconductors: MFeAs 2 (M=Ca, La. 112-type) [12] and A 2 Fe 4 Se 5 (A = K, Rb, Cs. 245type) [13].…”

Section: Introductionmentioning

confidence: 99%

Isovalent Substitution Effects of Arsenic on Structural and Electrical Properties of Iron-Based Superconductor NdFeAsO0.8F0.2

Alborzi

Daadmehr

2019

J Supercond Nov Magn

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“…However, one additional 3D hole pocket around Γ point and one more electron pocket at the Brillouin zone edge (X point) are contributed by 4p orbitals from As chains in hybridization with Fe 3d orbitals [42,43]. While filamentary superconductivity can be obtained in the pure La doped compounds [41,[44][45][46], further doping Co or Ni can improve the system to bulk superconductivity [5, 12-16, 18-26, 28, 29, 32, 36, 37]. (e) Photo of the coaligned Ca0.82La0.18Fe0.96Ni0.04As2 crystals.…”

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Neutron Spin Resonance in the 112-Type Iron-Based Superconductor

et al. 2018

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We use inelastic neutron scattering to study the low-energy spin excitations of the 112-type iron pnictide Ca_{0.82}La_{0.18}Fe_{0.96}Ni_{0.04}As_{2} with bulk superconductivity below T_{c}=22 K. A two-dimensional spin resonance mode is found around E=11 meV, where the resonance energy is almost temperature independent and linearly scales with T_{c} along with other iron-based superconductors. Polarized neutron analysis reveals the resonance is nearly isotropic in spin space without any L modulations. Because of the unique monoclinic structure with additional zigzag arsenic chains, the As 4p orbitals contribute to a three-dimensional hole pocket around the Γ point and an extra electron pocket at the X point. Our results suggest that the energy and momentum distribution of the spin resonance does not directly respond to the k_{z} dependence of the fermiology, and the spin resonance intrinsically is a spin-1 mode from singlet-triplet excitations of the Cooper pairs in the case of weak spin-orbital coupling.

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“…Furthermore, in the Ca 1−x La x Fe(As 1−y Sb y ) 2 simultaneously doped with La and Sb, the superconducting transition temperature rises up to 47 K [5]. According to single crystal X-ray structure analysis, Sb substitutes preferably to As in zigzag chains, rather than As in the FeAs layer [45], as predicted by first-principles calculations [46]. In contrast, excess doping of La causes antiferromagnetic and structural phase transitions [47][48][49], which results in loss of superconductivity.…”

Section: Arsenic Chains In the 112-type Structurementioning

confidence: 99%

Arsenic chemistry of iron-based superconductors and strategy for novel superconducting materials

Nohara

Kudo

2017

Advances in Physics: X

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The progress of materials discovery of iron-based superconductors is reviewed with the emphasis on the valence states and chemical bonds of arsenic. We demonstrate that monovalent As -produces the 112-type CaFeAs 2 with arsenic zigzag chains. When co-doping of La and Sb is performed, the superconducting transition temperature rises to 47 K. In the 10-4-8-type Ca 10 (Pt 4 As 8 )(Fe 2−x Pt x As 2 ) 5 , the divalent As 2-produces As 2 molecules, and creates an interlayer substance with PtAs 4 planar squares. The maximum superconducting transition temperature is 38 K. In the 122-type CaFe 2 As 2 , Rh doping induces a lattice collapse transition accompanying the formation of As 2 molecules between the adjacent FeAs layers. This transition can be viewed as a valence transition between As 3-and As 2-. These properties of arsenic that produces various chemical bonds can be used to create new superconducting materials.

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Site-Selective Antimony Doping in Arsenic Zigzag Chains of 112-Type Ca₁₋_xLa_xFeAs₂

Cited by 11 publications

References 21 publications

Isovalent Substitution Effects of Arsenic on Structural and Electrical Properties of Iron-Based Superconductor NdFeAsO0.8F0.2

Isovalent Substitution Effects of Arsenic on Structural and Electrical Properties of Iron-Based Superconductor NdFeAsO0.8F0.2

Neutron Spin Resonance in the 112-Type Iron-Based Superconductor

Arsenic chemistry of iron-based superconductors and strategy for novel superconducting materials

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