Effect of As-chain layers in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mtext>CaFeAs</mml:mtext><mml:mn>2</mml:mn></mml:msub></mml:math>

Wu, Xianxin; Le, Congcong; Liang, Yi; Qin, Shengshan; Fan, Heng; Hu, Jiangping

doi:10.1103/physrevb.89.205102

Cited by 52 publications

(69 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Second harmonic generation experiments confirmed the space group P 2 1 for La doped compounds [15]. More recently, theoretical studies focusing on the spacer layers determined that the As p x and p y orbitals are responsible for the Dirac cones, and the spin orbit coupling can open a gap and induce topological phases on these layers, suggesting the 112 compounds as prime candidates for proximity induced topological superconductivity [16,17].…”

Section: Introductionmentioning

confidence: 75%

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

2017

View full text Add to dashboard Cite

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.

show abstract

Section: Introductionmentioning

confidence: 75%

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

2017

View full text Add to dashboard Cite

show abstract

“…Thus, the S 4 symmetry for As 4p orbitals should be broken. The X and Y points would no longer be equivalent in BZ, and thus the Dirac-cone like feature could only be observed around one point 22,23 . Actually, our DFT calculation [ Fig.…”

Section: Pacs Numbersmentioning

confidence: 99%

“…Recently, high-temperature (high-T c ) superconductors such as Bi 2 Sr 2 CaCu 2 O 8+x (Bi-2212) have been also applied as the substrate materials to synthesize artificial topological insulator/superconductor heterostructures, based on the expectation that a larger superconducting gap could be resolved since more robust cooper pairs might be introduced into the normal side through superconducting proximity effect [19][20][21] . However, whether this proximity system can really host Majorana fermions is still lack of further support, and whether high-T c superconductors could work in realizing Majorana fermions is a seductive but still open question 22,23 .…”

Section: Pacs Numbersmentioning

confidence: 99%

“…Consequently, below T c the proximity effect would drive the zigzag As chain of the CaAs layer to become a one-dimensional topological superconductor. In this proposal, the key argument is that the p x and p y orbitals of the As atoms in the unique arsenic zigzag bond layers of CaFeAs 2 would result in an anisotropic Dirac cone near the Fermi level (E F ), which is gapped by the spin-orbit coupling (SOC) and topological nontrivial 22,23 . Once this Dirac-cone like band dispersion could be confirmed experimentally, the staggered intercalation of quantum spin Hall insulator and superconductor in this 112-type iron-based superconductor could provide us a unique opportunity to realize Majorana modes in solids.…”

Section: Pacs Numbersmentioning

confidence: 99%

See 1 more Smart Citation

Observation of the anisotropic Dirac cone in the band dispersion of 112-structured iron-based superconductor Ca0.9La0.1FeAs2

Liu

Xing

et al. 2016

Applied Physics Letters

View full text Add to dashboard Cite

CaFeAs 2 is a parent compound of recently discovered 112-type iron-based superconductors. It is predicted to be a staggered intercalation compound that naturally integrates both quantum spin Hall insulating and superconducting layers and an ideal system for the realization of Majorana modes. We performed a systematical angle-resolved photoemission spectroscopy and first-principle calculation study of the slightly electron-doped CaFeAs 2 . We found that the zigzag As chain of 112-type iron-based superconductors play a considerable role in the low-energy electronic structure, resulting in the characteristic Dirac-cone like band dispersion as the prediction. Our experimental results further confirm that these Dirac cones only exists around the X but not Y points in the Brillouin zone, breaking the S 4 symmetry at iron sites. Our findings present the compelling support to the theoretical prediction that the 112-type iron-based superconductors might host the topological nontrivial edge states. The slightly electron doped CaFeAs 2 would provide us a unique opportunity to realize and explore Majorana fermion physics.

show abstract

“…Searches for new iron-based superconductors have been still continuing, resulted in a recent discovery of new series of iron-based superconductors (Ca,RE)FeAs 2 ((Ca,RE)112) [5][6][7][8][9] . (Ca,RE)112 has several unique properties, such as monoclinic structure with space group of P2 1 or P2 1 /m, and co-existence of As -1 and As -3 in the crystal lattice [5,6] .…”

Section: Introductionmentioning

confidence: 99%

Dependences on RE of superconducting properties of transition metal co-doped (Ca,RE)FeAs2 with RE= La–Gd

Yakita

Sala

Okada

et al. 2015

Physica C: Superconductivity and its Applications

View full text Add to dashboard Cite

Dependence of superconducting properties of (Ca,RE)(Fe,TM)As 2 [(Ca,RE)112, TM: Co, Ni)] on RE elements (RE = La-Gd) was systematically investigated. Improvement of superconducting properties by Co or Ni co-doping was observed for all (Ca,RE)112, which is similar to Co-co-doped (Ca,La)112 or (Ca,Pr)112. T c of Co-co-doped samples decreased from 38 K for RE = La to 29 K for RE = Gd with decreasing ionic radii of RE 3+ . However, Co-co-doped (Ca,Eu)112 showed exceptionally low T c = 21 K probably due to the co-existence of Eu 3+ and Eu 2+ suggested by longer interlayer distance d Fe-Fe of (Ca,Eu)112 than other (Ca,RE)112.

show abstract

Effect of As-chain layers inCaFeAs2

Cited by 52 publications

References 39 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

Observation of the anisotropic Dirac cone in the band dispersion of 112-structured iron-based superconductor Ca0.9La0.1FeAs2

Dependences on RE of superconducting properties of transition metal co-doped (Ca,RE)FeAs2 with RE= La–Gd

Contact Info

Product

Resources

About