Abstract
The newly discovered iron-chalcogenide superconductor K x Fe2−y Se2 exhibits a distinct electronic structure from other iron-based superconductors. Exploiting polarization-dependent angle-resolved photoemission spectroscopy, we have determined the orbital characters of band structure in a K x Fe2−y Se2 superconductor. To a large extent, we find that K x Fe2−y Se2 superconductor shares similar orbital characters with other iron-based superconductors, but with its own characteristics. For example, we have resolved two highly degenerate electron cylinders around the zone corner in the s and p geometries, respectively, indicating negligible interactions between them. Moreover, in contrast to the band calculation results, the small electron pocket around Z is found to be mainly consisted of the d Z orbital. The determined orbital characters would help to construct a realistic model for K x Fe2−y Se2.
Article PDF
Similar content being viewed by others
References
Guo J G, Jin S F, Wang S C, et al. Superconductivity in the iron selenide KxFe2−y Se2 (0⩽ x ⩽1.0). Phys Rev B, 2010, 82: 180520
Luo Y K, Li Y K, Jiang S, et al. Phase diagram of CeFeAs1−x PxO obtained from electrical resistivity, magnetization, and specific heat measurements. Phys Rev B, 2010, 81: 134422
Hu W Z, Li G, Zheng P, et al. Optical study of the spin-densitywave properties of single-crystalline Na1−δFeAs. Phys Rev B, 2009, 80: 100507
Hu W Z, Dong J, Li G, et al. Origin of the spin density wave instability in AFe2As2 (A=Ba,Sr) as revealed by optical spectroscopy. Phys Rev Lett, 2008, 101: 257005
Yan Y J, Zhang M, Wang A F, et al. Electronic and magnetic phase diagram in KxFe2−y Se2 superconductors. Sci Rep, 2012, 2: 212
Craco L, Laad M S, Leoni S, et al. Unconventional Mott transition in KxFe2−y Se2. arXiv: 1109.0116v1
Chen F, Xu M, Ge Q Q, et al. Electronic identification of the parental phases and mesoscopic phase separation of KxFe2−y Se2 superconductors. Phys Rev X, 2011, 1: 021020
Chen Z G, Yuan R H, Dong T, et al. Infrared spectrum and its implications for the electronic structure of the semiconducting iron selenide K0.83Fe1.53Se2. Phys Rev B, 2011, 83: 220507
Cao C, Dai J H. Electronic structure of KFe2Se2 from first-principles calculations. Chin Phys Lett, 2011, 28: 057402
Li W, Ding H, Deng P, et al. Phase separation and magnetic order in K-doped iron selenide superconductor. Nat Phys, 2012, 8: 126–130
Zhang Y, Yang L X, Xu M, et al. Nodeless superconducting gap in KxFe2Se2 (A=K,Cs) revealed by angle-resolved photoemission spectroscopy. Nat Mater, 2011, 10: 273–277
Mou D X, Liu S Y, Jia X W, et al. Distinct Fermi surface topology and nodeless superconducting gap in a (Tl0.58Rb0.42)Fe1.72Se2 superconductor. Phys Rev Lett, 2011, 106: 107001
Yang L X, Xie B P, Zhang Y, et al. Surface and bulk electronic structures of LaFeAsO studied by angle-resolved photoemission spectroscopy. Phys Rev B, 2011, 82: 104519
Yang L X, Zhang Y, Ou H W, et al. Electronic structure and unusual exchange splitting in the spin-density-wave state of the BaFe2As2 parent compound of iron-based superconductors. Phys Rev Lett, 2009, 102: 107002
Zhang Y, Wei J, Ou HW, et al. Unusual doping dependence of the electronic structure and coexistence of spin-density-wave and superconductor phases in single crystalline Sr1−x KxFe2As2. Phys Rev Lett, 2009, 102: 127003
He C, Zhang Y, Xie B P, et al. Electronic-structure-driven magnetic and structure transitions in superconducting NaFeAs single crystals measured by angle-resolved photoemission spectroscopy. Phys Rev Lett, 2010, 105: 117002
Chen F, Zhou B, Zhang Y, et al. Electronic structure of Fe1.04Te0.66Se0.34. Phys Rev B, 2010, 81: 014526
Kuroki K, Onari S, Arita R, et al. Unconventional pairing originating from the disconnected Fermi surfaces of superconducting LaFeAsO1−x Fx. Phys Rev Lett, 2008, 101: 087004
Graser S, Maier T A, Hirschfeld P J, et al. Near-degeneracy of several pairing channels inmultiorbital models for the Fe pnictides. New J Phys, 2009, 11: 025016
Ran Y, Wang F, Zhai H, et al. Nodal spin density wave and band topology of the FeAs-based materials. Phys Rev B, 2009, 79: 014505
Zhang Y, Ye Z R, Ge Q Q, et al. Nodal superconducting-gap structure in ferropnictide superconductor BaFe2(As0.7P0.3)2. Nat Phys, 2012, 8: 371–375
Damascelli A, Hussain Z, Shen Z X. Angle-resolved photoemission studies of the cuprate superconductors. Rev Mod Phys, 2003, 75: 473–541
Zhang Y, Chen F, He C, et al. Orbital characters of bands in the iron-based superconductor BaFe1.85Co0.15As2. Phys Rev B, 2011, 83: 054510
Ye Z R, Zhang Y, Xu M, et al. Phosphor induced significant hole-doping in ferropnictide superconductor BaFe2(As1−x Px)2. arXiv: 1105.5242v1
Zhang Y, Yang L X, Chen F, et al. Out-of-plane momentum and symmetry-dependent energy gap of the pnictide Ba0.6K0.4Fe2As2 superconductor revealed by angle-resolved photoemission spectroscopy. Phys Rev Lett, 2010, 105: 117003
Wray L A, Hsieh D, Xia Y, et al. Observation of intertwined Fermi surface topology, orbital parity symmetries and electronic interactions in iron arsenide superconductors. arXiv: 0912.5089v1
Wang X P, Richard P, Huang Y B, et al. Orbital characters determined from Fermi surface intensity patterns using angle-resolved photoemission spectroscopy. arXiv: 1201.3655v1
Zhang Y, He C, Ye Z R, et al. Symmetry breaking via orbital-dependent reconstruction of electronic structure in detwinned NaFeAs. Phys Rev B, 2012, 85: 085121
Yi M, Lu D H, Moore R G, et al. Electronic reconstruction through the structural and magnetic transitions in detwinned NaFeAs. arXiv:1111. 6134v1
Khodas M, Chubukov A V. Inter-pocket pairing and gap symmetry in Fe-based superconductors with only electron pockets. arXiv: 1202.5563v1
Xu M, Ge Q Q, Peng R, et al. Evidence for an s-wave superconducting gap in KxFe2−y Se2 from angle-resolved photoemission. Phys Rev B, 2012, 85: 220504
Wang A F, Ying J J, Yan Y J, et al. Superconductivity at 32 K in singlecrystalline RbxFe2−y Se2. Phys Rev B, 2011, 83: 060512
Shen Z X. Private communication
Blaha P, Schwarz K, Madsen G K H, et al. WIEN2k: An augmented plane wave plus local orbitals program for calculating crystal properties. User’s Guide. Vienna: Vienna University of Technology, 2001
Liu Z H, Richard P, Xu N, et al. Three-dimensionality and orbital characters of Fermi surface in (Tl,Rb)yFe2−x Se2. arXiv: 1202.6417v2
Cai P, Ye C, Ruan W, et al. Imaging the coexistence of a superconducting phase and a charge-density modulation in the K0.73Fe1.67Se2 superconductor using a scanning tunneling microscope. Phys Rev B, 2012, 85: 094512
Li J Q, Song Y J, Yang H X, et al. Collapse of the Fe-vacancy order and successive phase transitions in superconducting KxFe2−y Se2 (0.7 ⩽x ⩽0.8, 0.2 ⩽ y ⩽0.3). arXiv: 1104.5340v1
Author information
Authors and Affiliations
Corresponding author
Additional information
This article is published with open access at Springerlink.com
Rights and permissions
This article is published under an open access license. Please check the 'Copyright Information' section either on this page or in the PDF for details of this license and what re-use is permitted. If your intended use exceeds what is permitted by the license or if you are unable to locate the licence and re-use information, please contact the Rights and Permissions team.
About this article
Cite this article
Chen, F., Ge, Q., Xu, M. et al. The orbital characters of low-energy electronic structure in iron-chalcogenide superconductor K x Fe2−y Se2 . Chin. Sci. Bull. 57, 3829–3835 (2012). https://doi.org/10.1007/s11434-012-5405-7
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11434-012-5405-7