Publisher's Note: Structural and magnetic phase transitions in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>Ca</mml:mi><mml:mrow><mml:mn>0.73</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mi>La</mml:mi><mml:mrow><mml:mn>0.27</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mi>FeAs</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>with electron-overdoped FeAs layers [Phys. Rev. B<b>93</b>, 054522 (2016)]

Jiang, Shan; Liu, Chang; Cao, Huibo; Birol, Turan; Allred, Jared M.; Tian, Wei; Liu, Lian; Cho, Kyuil; Krogstad, Matthew; Ma, Jie; Taddei, Keith M.; Tanatar, M. A.; Hoesch, Moritz; Prozorov, Ruslan; Rosenkranz, Stephan; Uemura, Y. J.; Kotliar, Gabriel; Ni, Ni

doi:10.1103/physrevb.93.099902

Cited by 14 publications

(55 citation statements)

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“…Raising the question of relative stability of these compounds, what is the role of the rare earth like La in stabilizing the structure? (3) Photoemission experiments, confirmed the theoretical prediction of the existence of metallic spacer layers (with Fermi pockets of As p z and Ca character, in addition to the Dirac cones) [19,20], however, it is not clear from them what the role of doping is, since in the 112 structure both the CaAs and the FeAs layers can accommodate carriers. (4) It would also be useful to establish consequences of the anisotropy introduced by the formation of the CaAs chains, which should be visible in the optical response, and elucidate how this anisotropy couples to the nematic order parameter whose origin is a subject of intensive discussion.…”

Section: Introductionmentioning

confidence: 51%

“…Ca 1−x La x FeAs 2 also undergoes a structural transition near its antiferromagnetic ordering temperature [19]. This transition is from monoclinic to triclinic symmetry.…”

Section: Figmentioning

confidence: 99%

“…[35]. We use the Coulomb interaction U = 5.0 eV and the Hund's coupling J = 0.8 eV, which were shown to describe Ca 1−x La x FeAs 2 compounds [19,36]. The temperature is set to T = 116 K. The experimental crystal structure determined by X-ray diffraction [14] is used.…”

Section: Methodsmentioning

confidence: 99%

“…A fast-dispersing band near the X point has the dominant character of the zig-zag As chain [19,20], and this band goes down below the Fermi level upon doping as shown in Fig. 8(b), indicating that the spacer of the zig-zag As chain has a crucial role in doping [19].…”

Section: Hypothetical Srfeas2 and Bafeas2 Compoundsmentioning

confidence: 99%

“…Since the parent compound of Ca 1−x La x FeAs 2 is regarded as Ca 0.7 La 0.3 FeAs 2 [19], the superconductivity in Ca 0.8 La 0.2 FeAs 2 arises from the hole doping through Ca substitution on the La sites. The resistivity anisotropy is a nonmonotonic function of doping as shown in Fig.…”

Section: Hypothetical Srfeas2 and Bafeas2 Compoundsmentioning

confidence: 99%

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Phase stability and large in-plane resistivity anisotropy in the 112-type iron-based superconductor Ca1−xLaxFeAs2

2017

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The recently discovered high-Tc superconductor Ca1−xLaxFeAs2 is a unique compound not only because of its low symmetry crystal structure, but also because of its electronic structure which hosts Dirac-like metallic bands resulting from (spacer) zig-zag As chains. We present a comprehensive first principles theoretical study of the electronic and crystal structures of Ca1−xLaxFeAs2. After discussing the connection between the crystal structure of the 112 family, which Ca1−xLaxFeAs2 is a member of, with the other known structures of Fe pnictide superconductors, we check the thermodynamic phase stability of CaFeAs2, and similar hyphothetical compounds SrFeAs2 and BaFeAs2 which, we find, are slightly higher in energy. We calculate the optical conductivity of Ca1−xLaxFeAs2 using the DFT + DMFT method, and predict a large in-plane resistivity anisotropy in the normal phase, which does not originate from electronic nematicity, but is enhanced by the electronic correlations. In particular, we predict a 0.34 eV peak in the yy component of the optical conductivity of the 30% La doped compound, which correponds to coherent interband transitions within a fast-dispersing band arising from the zig-zag As-chains which are unique to this compound. We also study the Landau free energy for Ca1−xLaxFeAs2 including the order parameter relevant for the nematic transition and find that the free energy does not have any extra terms that could induce ferro-orbital order. This explains why the presence of As chains does not broaden the nematic transition in Ca1−xLaxFeAs2.

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Section: Introductionmentioning

confidence: 51%

“…Ca 1−x La x FeAs 2 also undergoes a structural transition near its antiferromagnetic ordering temperature [19]. This transition is from monoclinic to triclinic symmetry.…”

Section: Figmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Hypothetical Srfeas2 and Bafeas2 Compoundsmentioning

confidence: 99%

Section: Hypothetical Srfeas2 and Bafeas2 Compoundsmentioning

confidence: 99%

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Phase stability and large in-plane resistivity anisotropy in the 112-type iron-based superconductor Ca1−xLaxFeAs2

2017

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Superconductivity and Dirac fermions in 112‐phase pnictides

Ray

Alff

2016

Physica Status Solidi (b)

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This article reviews the current research on the 112‐phase of pnictides. The 112‐phase has gained augmented attention due to the recent discovery of high‐temperature superconductivity in Ca1−xLaxFeAs2 with a maximum critical temperature Tnormalc∼ 47thinmathspacenormalK upon Sb substitution. The structural, magnetic, and electronic properties of Ca1−xLaxFeAs2 bear some similarities with other superconducting pnictide phases, however, the different valence states of the pnictogen and the presence of a metallic spacer layer are unique features of the 112‐system. Low‐temperature superconductivity which coexists with antiferromagnetic order was observed in transition metal (Ni, Pd) deficient 112‐compounds like CeNixBi2, LaPdxBi2, LaPdxSb2, LaNixSb2. Besides superconductivity, the presence of naturally occurring anisotropic Dirac Fermionic states were observed in the layered 112‐compounds SrMnBi2, CaMnBi2, LaAgBi2 which are of significant interest for future nanoelectronics as an alternative to graphene. In these compounds, the linear energy dispersion resulted in a high magnetoresistance that stayed unsaturated even at the highest applied magnetic fields. Here, we describe various 112‐type materials systems combining experimental results and theoretical predictions to stimulate further research on this less well‐known member of the pnictide family.

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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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Publisher's Note: Structural and magnetic phase transitions inCa0.73La0.27FeAs2with electron-overdoped FeAs layers [Phys. Rev. B93, 054522 (2016)]

Cited by 14 publications

References 0 publications

Phase stability and large in-plane resistivity anisotropy in the 112-type iron-based superconductor Ca1−xLaxFeAs2

Phase stability and large in-plane resistivity anisotropy in the 112-type iron-based superconductor Ca1−xLaxFeAs2

Superconductivity and Dirac fermions in 112‐phase pnictides

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

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