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Quasiparticle interference in LiFeAs: Signature of inelastic tunneling through spin fluctuations

Shun Chi1,2,*, Carolina A. Marques3, W. N. Hardy1,2, Ruixing Liang1,2, Pinder Dosanjh1,2, D. A. Bonn1,2, S. A. Burke1,2,4, and Peter Wahl3,5,†

  • *Deceased.
  • †Contact author: wahl@st-andrews.ac.uk
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Phys. Rev. B 113, 235148 – Published 24 June, 2026

DOI: https://doi.org/10.1103/6s6t-5396

Abstract

Quasiparticle interference (QPI) is a powerful tool to characterize the symmetry of the superconducting order parameter in unconventional superconductors, by mapping the spatial dependence of elastic tunneling of electrons between the tip of a scanning tunneling microscope and a sample. Here, we consider the influence of inelastic tunneling on quasiparticle interference, exemplarily for the iron-based superconductor LiFeAs. We clearly observe replica features in both experimental QPI maps and the dispersion extracted from QPI, which from comparison with theoretical model calculations can be attributed to inelastic tunneling. Analysis of the QPI dispersion shows that the inelastic mode that gives rise to these replica features exhibits a resonance between 8 and 10 meV. Comparison of the energy scale of the resonance energy estimated from QPI with inelastic neutron scattering indicates that the replica features arise from interaction with spin fluctuations.

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References (40)

  1. J. E. Hoffman, Spectroscopic scanning tunneling microscopy insights into Fe-based superconductors, Rep. Prog. Phys. 74, 124513 (2011).
  2. J. E. Hoffman, K. McElroy, D.-H. Lee, K. M. Lang, H. Eisaki, S. Uchida, and J. C. Davis, Imaging quasiparticle interference in Bi2Sr2CaCu2O8+δ, Science 297, 1148 (2002).
  3. T. Hanaguri, Y. Kohsaka, M. Ono, M. Maltseva, P. Coleman, I. Yamada, M. Azuma, M. Takano, K. Ohishi, and H. Takagi, Coherence factors in a high-Tc cuprate probed by quasi-particle scattering off vortices, Science 323, 923 (2009).
  4. M. P. Allan, F. Massee, D. K. Morr, J. Van Dyke, A. W. Rost, A. P. Mackenzie, C. Petrovic, and J. C. Davis, Imaging Cooper pairing of heavy fermions in CeCoIn5, Nat. Phys. 9, 468 (2013).
  5. B. B. Zhou, S. Misra, E. H. da Silva Neto, P. Aynajian, R. E. Baumbach, J. D. Thompson, E. D. Bauer, and A. Yazdani, Visualizing nodal heavy fermion superconductivity in CeCoIn5, Nat. Phys. 9, 474 (2013).
  6. A. Yazdani, E. H. da Silva Neto, and P. Aynajian, Spectroscopic imaging of strongly correlated electronic states, Annu. Rev. Condens. Matter Phys. 7, 11 (2016).
  7. B. C. Stipe, M. A. Rezaei, and W. Ho, Single-molecule vibrational spectroscopy and microscopy, Science 280, 1732 (1998).
  8. A. J. Heinrich, J. A. Gupta, C. P. Lutz, and D. M. Eigler, Single-atom spin-flip spectroscopy, Science 306, 466 (2004).
  9. S. Loth, C. P. Lutz, and A. J. Heinrich, Spin-polarized spin excitation spectroscopy, New J. Phys. 12, 125021 (2010).
  10. J. R. Kirtley and D. J. Scalapino, Inelastic-tunneling model for the linear conductance background in the high-Tc superconductors, Phys. Rev. Lett. 65, 798 (1990).
  11. S. Chi, R. Aluru, S. Grothe, A. Kreisel, U. R. Singh, B. M. Andersen, W. N. Hardy, R. Liang, D. A. Bonn, S. A. Burke, and P. Wahl, Imaging the real space structure of the spin fluctuations in an iron-based superconductor, Nat. Commun. 8, 15996 (2017).
  12. P. Hlobil, J. Jandke, W. Wulfhekel, and J. Schmalian, Tracing the electronic pairing glue in unconventional superconductors via inelastic scanning tunneling spectroscopy, Phys. Rev. Lett. 118, 167001 (2017).
  13. X.-Y. Hou, F. Zhang, X.-H. Tu, Y.-D. Gu, M.-D. Zhang, J. Gong, Y.-B. Tu, B.-T. Wang, W.-G. Lv, H.-M. Weng, Z.-A. Ren, G.-F. Chen, X.-D. Zhu, N. Hao, and L. Shan, Inelastic electron tunneling in 2H−TaxNb1−xSe2 evidenced by scanning tunneling spectroscopy, Phys. Rev. Lett. 124, 106403 (2020).
  14. T. Gozlinski, M. Henn, T. Wolf, M. Le Tacon, J. Schmalian, and W. Wulfhekel, Bosonic excitation spectra of superconducting and extracted from scanning tunneling spectra, J. Phys.: Condens. Matter 36, 175601 (2024).
  15. Ø. Fischer, M. Kugler, I. Maggio-Aprile, C. Berthod, and C. Renner, Scanning tunneling spectroscopy of high-temperature superconductors, Rev. Mod. Phys. 79, 353 (2007).
  16. Y. Yin, M. Zech, T. L. Williams, X. F. Wang, G. Wu, X. H. Chen, and J. E. Hoffman, Scanning tunneling spectroscopy and vortex imaging in the iron pnictide superconductor BaFe1.8Co0.2As2, Phys. Rev. Lett. 102, 097002 (2009).
  17. Z. Wang, H. Yang, D. Fang, B. Shen, Q.-H. Wang, L. Shan, C. Zhang, P. Dai, and H.-H. Wen, Close relationship between superconductivity and the bosonic mode in Ba0.6K0.4Fe2As2 and Na(Fe0.975Co0.025)As, Nat. Phys. 9, 42 (2013).
  18. S. Chi, S. Grothe, R. Liang, P. Dosanjh, W. N. Hardy, S. A. Burke, D. A. Bonn, and Y. Pennec, Scanning tunneling spectroscopy of superconducting LiFeAs single crystals: Evidence for two nodeless energy gaps and coupling to a bosonic mode, Phys. Rev. Lett. 109, 087002 (2012).
  19. S. V. Borisenko, V. B. Zabolotnyy, D. V. Evtushinsky, T. K. Kim, I. V. Morozov, A. N. Yaresko, A. A. Kordyuk, G. Behr, A. Vasiliev, R. Follath, and B. Büchner, Superconductivity without nesting in LiFeAs, Phys. Rev. Lett. 105, 067002 (2010).
  20. K. Umezawa, Y. Li, H. Miao, K. Nakayama, Z.-H. Liu, P. Richard, T. Sato, J. B. He, D.-M. Wang, G. F. Chen, H. Ding, T. Takahashi, and S.-C. Wang, Unconventional anisotropic s-wave superconducting gaps of the LiFeAs iron-pnictide superconductor, Phys. Rev. Lett. 108, 037002 (2012).
  21. R. P. Day, M. X. Na, M. Zingl, B. Zwartsenberg, M. Michiardi, G. Levy, M. Schneider, D. Wong, P. Dosanjh, T. M. Pedersen, S. Gorovikov, S. Chi, R. Liang, W. N. Hardy, D. A. Bonn, S. Zhdanovich, I. S. Elfimov, and A. Damascelli, Three-dimensional electronic structure of LiFeAs, Phys. Rev. B 105, 155142 (2022).
  22. T. Hanaguri, K. Kitagawa, K. Matsubayashi, Y. Mazaki, Y. Uwatoko, and H. Takagi, Scanning tunneling microscopy/spectroscopy of vortices in LiFeAs, Phys. Rev. B 85, 214505 (2012).
  23. M. P. Allan, A. W. Rost, A. P. Mackenzie, Y. Xie, J. C. Davis, K. Kihou, C. H. Lee, A. Iyo, H. Eisaki, and T.-M. Chuang, Anisotropic energy gaps of iron-based superconductivity from intraband quasiparticle interference in LiFeAs, Science 336, 563 (2012).
  24. B. Li, Z. W. Xing, and M. Liu, Phonon softening induced by striped antiferromagnetic order in LiFeAs, Appl. Phys. Lett. 98, 072506 (2011).
  25. A. E. Taylor, M. J. Pitcher, R. A. Ewings, T. G. Perring, S. J. Clarke, and A. T. Boothroyd, Antiferromagnetic spin fluctuations in LiFeAs observed by neutron scattering, Phys. Rev. B 83, 220514(R) (2011).
  26. N. Qureshi, P. Steffens, Y. Drees, A. C. Komarek, D. Lamago, Y. Sidis, L. Harnagea, H.-J. Grafe, S. Wurmehl, B. Büchner, and M. Braden, Inelastic neutron-scattering measurements of incommensurate magnetic excitations on superconducting LiFeAs single crystals, Phys. Rev. Lett. 108, 117001 (2012).
  27. N. Qureshi, P. Steffens, D. Lamago, Y. Sidis, O. Sobolev, R. A. Ewings, L. Harnagea, S. Wurmehl, B. Büchner, and M. Braden, Fine structure of the incommensurate antiferromagnetic fluctuations in single-crystalline LiFeAs studied by inelastic neutron scattering, Phys. Rev. B 90, 144503 (2014).
  28. S. Chi, S. Johnston, G. Levy, S. Grothe, R. Szedlak, B. Ludbrook, R. Liang, P. Dosanjh, S. A. Burke, A. Damascelli, D. A. Bonn, W. N. Hardy, and Y. Pennec, Sign inversion in the superconducting order parameter of LiFeAs inferred from Bogoliubov quasiparticle interference, Phys. Rev. B 89, 104522 (2014).
  29. M. P. Allan, K. Lee, A. W. Rost, M. H. Fischer, F. Massee, K. Kihou, C.-H. Lee, A. Iyo, H. Eisaki, T.-M. Chuang, et al., Identifying the 'fingerprint'of antiferromagnetic spin fluctuations in iron pnictide superconductors, Nat. Phys. 11, 177 (2015).
  30. A. J. Macdonald, Y. S. Tremblay-Johnston, S. Grothe, S. Chi, P. Dosanjh, S. Johnston, and S. A. Burke, Dispersing artifacts in FT-STS: A comparison of set point effects across acquisition modes, Nanotechnology 27, 414004 (2016).
  31. P. O. 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).
  32. C. Berthod and T. Giamarchi, Tunneling conductance and local density of states in tight-binding junctions, Phys. Rev. B 84, 155414 (2011).
  33. J. Tersoff and D. R. Hamann, Theory of the scanning tunneling microscope, Phys. Rev. B 31, 805 (1985).
  34. Y. Zhang, V. W. Brar, F. Wang, C. Girit, Y. Yayon, M. Panlasigui, A. Zettl, and M. F. Crommie, Giant phonon-induced conductance in scanning tunnelling spectroscopy of gate-tunable graphene, Nat. Phys. 4, 627 (2008).
  35. A. Mitra, A. Corticelli, P. Ribeiro, and P. A. McClarty, Magnon interference tunneling spectroscopy as a probe of 2D magnetism, Phys. Rev. Lett. 130, 066701 (2023).
  36. S. Chi et al., Data for “Quasiparticle interference in LiFeAs: Signature of inelastic tunneling through spin fluctuations,” 2026, https://doi.org/10.17605/OSF.IO/MDB3V.
  37. M. N. Gastiasoro, P. J. Hirschfeld, and B. M. Andersen, Impurity states and cooperative magnetic order in Fe-based superconductors, Phys. Rev. B 88, 220509(R) (2013).
  38. S. C. White, U. R. Singh, and P. Wahl, A stiff scanning tunneling microscopy head for measurement at low temperatures and in high magnetic fields, Rev. Sci. Instrum. 82, 113708 (2011).
  39. P. Wahl, L. C. Rhodes, and C. A. Marques, calcQPI: A versatile tool to simulate quasiparticle interference, SciPost Phys. Codebases 61 (2025).
  40. See Supplemental Material at http://link.aps.org/supplemental/10.1103/6s6t-5396 for a movie of the quasiparticle interference.

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Phys. Rev. B 113, 235148– Published 24 June, 2026
  • Received 15 August 2025
  • Revised 20 May 2026
  • Accepted 5 June 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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