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Spectroscopic Evidence for an Additional Symmetry Breaking in the Nematic State of FeSe Superconductor

Cong Li1,2, Xianxin Wu1,3, Le Wang1,2, Defa Liu1,4, Yongqing Cai1,2, Yang Wang1,2, Qiang Gao1,2, Chunyao Song1,2, Jianwei Huang1,2 et al.

Chenxiao Dong1,2, Jing Liu1,2, Ping Ai1,2, Hailan Luo1,2, ChaoHui Yin1,2, Guodong Liu1, Yuan Huang1, Qingyan Wang1, Xiaowen Jia5, Fengfeng Zhang6, Shenjin Zhang6, Feng Yang6, Zhimin Wang6, Qinjun Peng6, Zuyan Xu6, Youguo Shi1,2, Jiangping Hu1,2,9, Tao Xiang1,2,9, Lin Zhao1,*, and X. J. Zhou1,2,7,8,†

  • 1Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
  • 2University of Chinese Academy of Sciences, Beijing 100049, China
  • 3Institute for Theoretical Physics and Astrophysics, Julius-Maximilians University of Wurzburg, Am Hubland, D-97074 Wurzburg, Germany
  • 4Max Planck Institute of Microstructure Physics, Weinberg 2, Halle 06120, Germany
  • 5Military Transportation University, Tianjin 300161, China
  • 6Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China
  • 7Songshan Lake Materials Laboratory, Dongguan 523808, China
  • 8Beijing Academy of Quantum Information Sciences, Beijing 100193, China
  • 9Collaborative Innovation Center of Quantum Matter, Beijing 100190, China

  • *Corresponding author. lzhao@iphy.ac.cn
  • †Corresponding author. XJZhou@iphy.ac.cn
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Phys. Rev. X 10, 031033 – Published 12 August, 2020

DOI: https://doi.org/10.1103/PhysRevX.10.031033

Abstract

The iron-based superconductor FeSe has attracted much recent attention because of its simple crystal structure, distinct electronic structure, and rich physics exhibited by itself and its derivatives. Determination of its intrinsic electronic structure is crucial to understanding its physical properties and superconductivity mechanism. Both theoretical and experimental studies so far have provided a picture that FeSe consists of one holelike Fermi surface around the Brillouin zone center in its nematic state. Here we report direct observation of two holelike Fermi surface sheets around the Brillouin zone center, and the splitting of the associated bands, in the nematic state of FeSe by taking high-resolution laser-based angle-resolved photoemission measurements. These results indicate that, in addition to nematic order and spin-orbit coupling, there is an additional order in FeSe that breaks either inversion or time-reversal symmetries. The new Fermi surface topology asks for reexamination of the existing theoretical and experimental understanding of FeSe and stimulates further efforts to identify the origin of the hidden order in its nematic state.

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Popular Summary

The iron-based superconductor FeSe has a simple crystal structure and a rich electronic behavior that carries over to superconductors derived from it. To take full advantage of FeSe and better understand its physical properties and superconductivity mechanism, researchers need a clear picture of its electronic structure. To that end, we conduct experiments that take a deeper look at FeSe’s electronic structure and find greater complexity than was previously known.

To get a complete picture of a material’s electronic structure, researchers need information about its Fermi surface and band structure. The Fermi surface is a “surface” in momentum space that separates occupied electron states from unoccupied ones; the band structure describes the range of energy levels that electrons may occupy.

We use angle-resolved photoemission spectroscopy—a technique that uses light to liberate electrons, whose energy and momentum provide details about the electronic structure—to probe the Fermi surface and band structure of FeSe. Contrary to previous work, we find a two-hole-like Fermi surface sheet and a splitting of one band into two. We attribute these findings to some additional unknown “order”—or state of matter—in FeSe. It is already known that FeSe features nematicity, a state where the crystal structure differs little along perpendicular axes, while the electronic and physical properties differ a lot. Some have suggested that this nematicity is related to the superconductivity, but we find that it alone cannot explain the observed electronic structure.

We hope this work can stimulate further effort to identify the hidden order and provide new information in understanding the nematicity and superconductivity in FeSe.

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References (59)

  1. F. Hsu et al., Superconductivity in the PbO-type Structure α-FeSe, Proc. Natl. Acad. Sci. U.S.A. 105, 14262 (2008).
  2. T. M. McQueen, A. J. Williams, P. W. Stephens, J. Tao, Y. Zhu, V. Ksenofontov, F. Casper, C. Felser, and R. J. Cava, Tetragonal-to-Orthorhombic Structural Phase Transition at 90 K in the Superconductor Fe1.01Se, Phys. Rev. Lett. 103, 057002 (2009).
  3. S. Medvedev et al., Electronic and Magnetic Phase Diagram of β-Fe1.01Se with Superconductivity at 36.7 K Under Pressure, Nat. Mater. 8, 630 (2009).
  4. J. P. Sun et al., Dome-Shaped Magnetic Order Competing with High-Temperature Superconductivity at High Pressures in FeSe, Nat. Commun. 7, 12146 (2016).
  5. J. Maletz, V. B. Zabolotnyy, D. V. Evtushinsky, S. Thirupathaiah, A. U. B. Wolter, L. Harnagea, A. N. Yaresko, A. N. Vasiliev, D. A. Chareev, A. E. Bohmer et al., Unusual Band Renormalization in the Simplest Iron-Based Superconductor FeSe1−x, Phys. Rev. B 89, 220506(R) (2014).
  6. K. Nakayama, Y. Miyata, G. N. Phan, T. Sato, Y. Tanabe, T. Urata, K. Tanigaki, and T. Takahashi, Reconstruction of Band Structure Induced by Electronic Nematicity in an FeSe Superconductor, Phys. Rev. Lett. 113, 237001 (2014).
  7. T. Shimojima et al., Lifting of xz/yz Orbital Degeneracy at the Structural Transition in Detwinned FeSe, Phys. Rev. B 90, 121111(R) (2014).
  8. P. Zhang et al., Observation of Two Distinct dxz/dyz Band Splittings in FeSe, Phys. Rev. B 91, 214503 (2015).
  9. Y. Suzuki, T. Shimojima, T. Sonobe, A. Nakamura, M. Sakano, H. Tsuji, J. Omachi, K. Yoshioka, M. Kuwata-Gonokami, T. Watashige et al., Momentum-Dependent Sign Inversion of Orbital Order in Superconducting FeSe, Phys. Rev. B 92, 205117 (2015).
  10. M. D. Watson et al., Emergence of the Nematic Electronic State in FeSe, Phys. Rev. B 91, 155106 (2015).
  11. M. D. Watson, T. K. Kim, L. C. Rhodes, M. Eschrig, M. Hoesch, A. A. Haghighirad, and A. I. Coldea, Evidence for Unidirectional Nematic Bond Ordering in FeSe, Phys. Rev. B 94, 201107(R) (2016).
  12. M. D. Watson, A. A. Haghighirad, L. C. Rhodes, M. Hoesch, and T. K. Kim, Electronic Anisotropies Revealed by Detwinned Angle-Resolved Photoemission Spectroscopy Measurements of FeSe, New J. Phys. 19, 103021 (2017).
  13. H. C. Xu, X. H. Niu, D. F. Xu, J. Jiang, Q. Yao, Q. Y. Chen, Q. Song, M. Abdel-Hafiez, D. A. Chareev, A. N. Vasiliev et al., Highly Anisotropic and Twofold Symmetric Superconducting Gap in Nematically Ordered FeSe0.93S0.07, Phys. Rev. Lett. 117, 157003 (2016).
  14. T. Hashimoto et al., Superconducting Gap Anisotropy Sensitive to Nematic Domains in FeSe, Nat. Commun. 9, 282 (2018).
  15. D. Liu, C. Li, J. Huang, B. Lei, L. Wang, X. Wu, B. Shen, Q. Gao, Y. Zhang, X. Liu et al., Orbital Origin of Extremely Anisotropic Superconducting Gap in Nematic Phase of FeSe Superconductor, Phys. Rev. X 8, 031033 (2018).
  16. L. C. Rhodes, M. D. Watson, A. A. Haghighirad, D. V. Evtushinsky, M. Eschrig, and T. K. Kim, Scaling of the Superconducting Gap with Orbital Character in FeSe, Phys. Rev. B 98, 180503(R) (2018).
  17. Y. Kushnirenko, A. V. Fedorov, E. Haubold, S. Thirupathaiah, T. Wolf, S. Aswartham, I. Morozov, T. K. Kim, B. Büchner, and S. V. Borisenko, Three-Dimensional Superconducting Gap in FeSe from Angle-Resolved Photoemission Spectroscopy, Phys. Rev. B 97, 180501(R) (2018).
  18. H. Pfau et al., Momentum Dependence of the Nematic Order Parameter in Iron-Based Superconductors, Phys. Rev. Lett. 123, 066402 (2019).
  19. M. D. Watson, A. A. Haghighirad, H. Takita, W. Mansuer, H. Iwasawa, E. F. Schwier, A. Ino, and M. Hoesch, Shifts and Splittings of the Hole Bands in the Nematic Phase of FeSe, J. Phys. Soc. Jpn. 86, 053703 (2017).
  20. S. Kasahara et al., Field-Induced Superconducting Phase of FeSe in the BCS-BEC Crossover, Proc. Natl. Acad. Sci. U.S.A. 111, 16309 (2014).
  21. P. Sprau, A. Kostin, A. Kreisel, A. E. Böhmer, V. Taufour, P. C. Canfield, S. Mukherjee, P. J. Hirschfeld, B. M. Andersen, and J. C. S. Davis, Discovery of Orbital-Selective Cooper Pairing in FeSe, Science 357, 75 (2017).
  22. T. Hanaguri, S. Kasahara, J. Boker, I. Eremin, T. Shibauchi, and Y. Matsuda, Quantum Vortex Core and Missing Pseudogap in the Multiband BCS-BEC Crossover Superconductor FeSe, Phys. Rev. Lett. 122, 077001 (2019).
  23. T. Terashima, N. Kikugawa, A. Kiswandhi, E. S. Choi, J. S. Brooks, S. Kasahara, T. Watashige, H. Ikeda, T. Shibauchi, Y. Matsuda et al., Anomalous Fermi Surface in FeSe Seen by Shubnikov–de Haas Oscillation Measurements, Phys. Rev. B 90, 144517 (2014).
  24. M. D. Watson et al., Dichotomy between the Hole and Electron Behavior in Multiband Superconductor FeSe Probed by Ultrahigh Magnetic Fields, Phys. Rev. Lett. 115, 027006 (2015).
  25. J. Guo, S. Jin, G. Wang, S. Wang, K. Zhu, T. Zhou, M. He, and X. Chen, Superconductivity in the Iron Selenide KxFe2Se2 (0≤x≤1), Phys. Rev. B 82, 180520(R) (2010).
  26. T. P. Ying, X. Chen, G. Wang, S. Jin, X. Lai, T. Zhou, H. Zhang, S. Shen, and W. Wang, Superconducting Phases in Potassium-Intercalated Iron Selenides, J. Am. Chem. Soc. 135, 2951 (2013).
  27. T. P. Ying, X. L. Chen, G. Wang, S. F. Jin, T. T. Zhou, X. F. Lai, H. Zhang, and W. Y. Wang, Observation of Superconductivity at 30–46 K in AxFe2Se2 (A=Li, Na, Ba, Sr, Ca, Yb, and Eu), Sci. Rep. 2, 426 (2012).
  28. A. K. Maziopa, E. V. Pomjakushina, V. Yu. Pomjakushin, F. von Rohr, A. Schilling, and K. Conder, Synthesis of a New Alkali Metal-Organic Solvent Intercalated Iron Selenide Superconductor with Tc∼45  K, J. Phys. Condens. Matter 24, 382202 (2012).
  29. M. B. Lucas et al., Enhancement of the Superconducting Transition Temperature of FeSe by Intercalation of a Molecular Spacer Layer, Nat. Mater. 12, 15 (2013).
  30. T. Hatakeda, T. Noji, T. Kawamata, M. Kato, and Y. Koike, New Li-Ethylenediamine-Intercalated Superconductor Lix(C2H8N2)yFe2−zSe2 with Tc=45  K, J. Phys. Soc. Jpn. 82, 123705 (2013).
  31. M. Z. Shi, N. Z. Wang, B. Lei, C. Shang, F. B. Meng, L. K. Ma, F. X. Zhang, D. Z. Kuang, and X. H. Chen, Organic-Ion-Intercalated FeSe-Based Superconductors, Phys. Rev. Mater. 2, 074801 (2018).
  32. X. F. Lu et al., Coexistence of Superconductivity and Antiferromagnetism in (Li0.8Fe0.2)OHFeSe, Nat. Mater. 14, 325 (2015).
  33. B. Lei, J.  H. Cui, Z.  J. Xiang, C. Shang, N.  Z. Wang, G.  J. Ye, X.  G. Luo, T. Wu, Z. Sun, and X.  H. Chen, Evolution of High-Temperature Superconductivity from Low-Tc Phase Tuned by Carrier Concentration in FeSe Thin Flakes, Phys. Rev. Lett. 116, 077002 (2016).
  34. B. Lei et al., Tuning Phase Transitions in FeSe Thin Flakes by Field-Effect Transistor with Solid Ion Conductor as the Gate Dielectric, Phys. Rev. B 95, 020503(R) (2017).
  35. J. Seo, B. Y. Kim, B. S. Kim, J. K. Jeong, J. M. Ok, J. S. Kim, J. D. Denlinger, S.-K. Mo, C. Kim, and Y. K. Kim, Superconductivity Below 20 K in Heavily Electron-Doped Surface Layer of FeSe Bulk Crystal, Nat. Commun. 7, 11116 (2016).
  36. Q. Y. Wang et al., Interface-Induced High-Temperature Superconductivity in Single Unit-Cell FeSe Films on SrTiO3, Chin. Phys. Lett. 29, 037402 (2012).
  37. D. F. Liu et al., Electronic Origin of High-Temperature Superconductivity in Single-Layer FeSe Superconductor, Nat. Commun. 3, 931 (2012).
  38. S. L. He et al., Phase Diagram and Electronic Indication of High-Temperature Superconductivity at 65 K in Single-Layer FeSe Films, Nat. Mater. 12, 605 (2013).
  39. S. Y. Tan et al., Interface-Induced Superconductivity and Strain-Dependent Spin Density Waves in FeSe/SrTiO3 Thin Films,. Nat. Mater. 12, 634 (2013).
  40. J. J. Lee et al., Interfacial Mode Coupling as the Origin of the Enhancement of Tc in FeSe Films on SrTiO3, Nature (London) 515, 245 (2014).
  41. H. Hu, R. Yu, E. M. Nica, J. X. Zhu, and Q. Si, Orbital-Selective Superconductivity in the Nematic Phase of FeSe, Phys. Rev. B 98, 220503(R) (2018).
  42. J. Kang, R. M. Fernandes, and A. Chubukov, Superconductivity in FeSe: The Role of Nematic Order, Phys. Rev. Lett. 120, 267001 (2018).
  43. G. Y. Chen, X. Zhu, H. Yang, and H. H. Wen, Highly Anisotropic Superconducting Gaps and Possible Evidence of Antiferromagnetic Order in FeSe Single Crystals, Phys. Rev. B 96, 064524 (2017).
  44. P. K. Biswas, A. Kreisel, Q. Wang, D. T. Adroja, A. D. Hillier, J. Zhao, R. Khasanov, J.-C. Orain, A. Amato, and E. Morenzoni, Evidence of Nodal Gap Structure in the Basal Plane of the FeSe Superconductor, Phys. Rev. B 98, 180501(R) (2018).
  45. F. Hardy et al., Calorimetric Evidence of Nodal Gaps in the Nematic Superconductor FeSe, Phys. Rev. B 99, 035157 (2019).
  46. A. Kreisel, B. M. Andersen, P. O. Sprau, A. Kostin, J. C. S. Davis, and P. J. Hirschfeld, Orbital Selective Pairing and Gap Structures of Iron-Based Superconductors, Phys. Rev. B 95, 174504 (2017).
  47. L. Benfatto, B. Valenzuela, and L. Fanfarillo, Nematic Pairing from Orbital-Selective Spin Fluctuations in FeSe, npj Quantum Mater. 3, 56 (2018).
  48. X. J. Zhou, S. He, G. Liu, L. Zhao, L. Yu, and W. Zhang, New Developments in Laser-Based Photoemission Spectroscopy and Its Scientific Applications: A Key Issues Review, Rep. Prog. Phys. 81, 062101 (2018).
  49. See Supplemental Material at http://link.aps.org/supplemental/10.1103/PhysRevX.10.031033 for details on electronic structure analysis of single domain FeSe, temperature dependent Fermi surface mappings of single domain FeSe, and kz dispersion around the Brillouin zone center using different photon energies.
  50. L. Fanfarillo, J. Mansart, P. Toulemonde, H. Cercellier, P. LeFevre, F. Bertran, B. Valenzuela, L. Benfatto, and V. Brouet, Orbital-Dependent Fermi Surface Shrinking as a Fingerprint of Nematicity in FeSe, Phys. Rev. B 94, 155138 (2016).
  51. S. Hufner, in Photoelectron Spectroscopy: Principles and Applications, Springer Series in Solid State Sciences Vol. 82 (Springer, Berlin, 1995).
  52. G. D. Liu et al., Development of a Vacuum Ultra-Violet Laser-Based Angle-Resolved Photoemission System with a Super-High Energy Resolution Better than 1 meV, Rev. Sci. Instrum. 79, 023105 (2008).
  53. T. Watashige et al., Evidence for Time-Reversal Symmetry Breaking of the Superconducting State Near Twin-Boundary Interfaces in FeSe Revealed by Scanning Tunneling Spectroscopy, Phys. Rev. X 5, 031022 (2015).
  54. X. L. Qi, T. L. Hughes, and S. C. Zhang, Topological Invariants for the Fermi Surface of a Time-Reversal-Invariant Superconductor, Phys. Rev. B 81, 134508 (2010).
  55. A. E. Böhmer, F. Hardy, F. Eilers, D. Ernst, P. Adelmann, P. Schweiss, T. Wolf, and C. Meingast, Lack of Coupling between Superconductivity and Orthorhombic Distortion in Stoichiometric Single-Crystalline FeSe, Phys. Rev. B 87, 180505(R) (2013).
  56. Y. Zhang et al., Electronic Evidence of Temperature Induced Lifshitz Transition and Topological Nature in ZrTe5, Nat. Commun. 8, 15512 (2017).
  57. Y. Su, H. Liao, and T. Li, The Form and Origin of Orbital Ordering in the Electronic Nematic Phase of Iron-Based Superconductors, J. Phys. Condens. Matter 27, 105702 (2015).
  58. X. Wu et al., Nematic Orders and Nematicity-Driven Topological Phase Transition in FeSe, arXiv:1603.02055.
  59. T. Li and Y. Su, Driving Force of the Orbital-Relevant Electronic Nematicity in Fe-Based Superconductors, J. Phys. Condens. Matter 29, 425603 (2017).

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Phys. Rev. X 10, 031033– Published 12 August, 2020
  • Received 13 February 2020
  • Revised 11 May 2020
  • Accepted 16 June 2020
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