The effect of As-Chain layers in CaFeAs${}_2$

Abstract

The new discovered iron-based superconductors have chain-like As layers. These layers generate an additional 3-dimensional hole pocket and cone-like electron pockets. The former is attributed to the Ca $d$ and As1 $p_z$ orbitals and the latter are attributed to the anisotropic Dirac cone, contributed by As1 $p_x$ and $p_y$ orbitals. We find that large gaps on these pockets open in the collinear antiferromagnetic ground state of CaFeAs${}_2$, suggesting that the chain-like As layers are strongly coupled to FeAs layers. Moreover due to the low symmetry crystal induced by the As layers, the bands attributed to FeAs layers in $k_y=\pi$ plane are two-fold degenerate but in $k_x=\pi$ plane are lifted. This degeneracy is protected by a hidden symmetry $\widehat{{\rm Y}}=\hat{T}{\hat{R}}_y$. Ignoring the electron cones, the materials can be well described by a six-band model, including five Fe $d$ and As1 $p_z$ orbitals. We suggest that these new features may help us to identify the sign change and pairing symmetry in iron based superconductors.

7 pages, 10 figures

References in corpus (16)

• Superconductivity at 38 K in the iron arsenide (Ba1-xKx)Fe2As2
• Unconventional pairing originating from disconnected Fermi surfaces in superconducting LaFeAsO${}_{1-x}$F${}_x$}
• LaFeAsO${}_{1-x}$F${}_x$: A low carrier density superconductor near itinerant magnetism
• Spin density wave anomaly at 140 K in the ternary iron arsenide BaFe2As2
• The superconductivity at 18 K in LiFeAs system
• Near-degeneracy of several pairing channels in multiorbital models for the Fe-pnictides
• Thorium-doping induced superconductivity up to 56 K in Gd1-xThxFeAsO
• Funtional Renormalization Group Study of the Pairing Symmetry and Pairing Mechanism of the FeAs Based High Temperature Superconductors
• Electronic Structure and Doping in BaFe${}_2$As${}_2$ and LiFeAs: Density Functional Calculations
• Pairing Symmetry in a Two-Orbital Exchange Coupling Model of Oxypnictides
• The challenge of unravelling magnetic properties in LaFeAsO
• Electron-Hole Symmetry and Magnetic Coupling in Antiferromagnetic LaOFeAs
• d-wave pairing from spin fluctuations in the KxFe{2-y}Se2 superconductors
• Superconductivity in Ca1-xLaxFeAs2: A Novel 112-Type Iron Pnictide with Arsenic Zigzag Bonds
• Inter-pocket pairing and gap symmetry in Fe-based superconductors with only electron pockets
• Discovery of New Layered Iron Arsenide Superconductor (Ca,Pr)FeAs2

Cited by in corpus (18)

• Topological Characters in Fe(Te${}_{1-x}$Se${}_x$) thin films
• Topological quantum states of matter in iron-based superconductors: From concepts to material realization
• Boundary-obstructed topological high-T${}_c$ superconductivity in iron pnictides
• CaFeAs${}_2$: a Staggered Intercalation of Quantum Spin Hall and High Temperature Superconductivity
• Correlated materials design: prospects and challenges
• Doping-Enhanced Antiferromagnetism in Ca1-xLaxFeAs2
• Structural and magnetic phase transitions in Ca${}_{0.73}$La${}_{0.27}$FeAs${}_2$ with electron overdoped FeAs layers
• Significant contribution of As 4p orbitals to the low-lying electronic structure of 112-type iron-based superconductor Ca0.9La0.1FeAs2
• Anisotropic Ginzburg-Landau scaling of Hc2 and transport properties of 112-type Ca0.8La0.2Fe0.98Co0.02As2 single crystal
• Discovery of a novel 112-type iron-pnictide and La-doping induced superconductivity in Eu1-xLaxFeAs2 (x = 0 ~ 0.15)
• Superconductivity and Dirac Fermions in 112-phase Pnictides
• Observation of the anisotropic Dirac cone in the band dispersion of 112-structured iron-based superconductor Ca0.9La0.1FeAs2
• Phase stability and large in-plane resistivity in the 112-type iron-based superconductor Ca${}_{1-x}$La${}_x$FeAs${}_2$
• Co-doping effects on magnetism and superconductivity in the 112-type EuFeAs2 system
• Site-Selective Antimony Doping in Arsenic Zigzag Chains of 112-type Ca1-xLaxFeAs2
• Magnetic and superconducting phase diagram of Eu(Fe${}_{1-x}$Ni${}_x$)As${}_2$
• First-principle study of antimony doping effects on the iron-based superconductor CaFe(Sb${}_x$As${}_{1-x}$)${}_2$
• Persistent antiferromagnetic order in heavily overdoped Ca${}_{1-x}$La${}_x$FeAs${}_2$