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Field-Induced Magnon Decay, Magnon Shadows, and Rotonlike Excitations in the Honeycomb Antiferromagnet YbBr3

J. A. Hernández1, A. A. Eberharter2, M. Schuler3, J. Lass1, D. G. Mazzone1, R. Sibille1, S. Raymond4, K. W. Krämer5, B. Normand2,6 et al.

B. Roessli1, A. M. Läuchli2,6, and M. Kenzelmann1

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Phys. Rev. Lett. 135, 146701 – Published 3 October, 2025

DOI: https://doi.org/10.1103/q29r-8x1m

Abstract

Although the search for quantum many-body phenomena in magnetic materials has a strong focus on highly frustrated systems, even unfrustrated quantum magnets show a multitude of unconventional phenomena in their spin excitation spectra. YbBr3 is an excellent realization of the S=1/2 antiferromagnetic Heisenberg model on the honeycomb lattice, and we have performed detailed spectroscopic experiments with both unpolarized and polarized neutrons at all applied magnetic fields up to saturation. We observe extensive excitation continua, which cause strong renormalization and the decay of single magnons at higher fields, while coherent features include field-induced “shadows” of the single magnons and the spectacular emergence of a rotonlike excitation. To guide and interpret our experiments, we performed systematic calculations by the method of cylinder matrix-product states that provide quantitative agreement with the neutron scattering data and a qualitative benchmark for the spectral signatures of strong quantum fluctuations even in the absence of magnetic frustration.

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References (68)

  1. L. Savary and L. Balents, Quantum spin liquids: A review, Rep. Prog. Phys. 80, 016502 (2016).
  2. C. Broholm, R. J. Cava, S. A. Kivelson, D. G. Nocera, M. R. Norman, and T. Senthil, Quantum spin liquids, Science 367, eaay0668 (2020).
  3. M. E. Zhitomirsky and A. L. Chernyshev, Instability of antiferromagnetic magnons in strong fields, Phys. Rev. Lett. 82, 4536 (1999).
  4. A. Lüscher and A. M. Läuchli, Exact diagonalization study of the antiferromagnetic spin-1/2 Heisenberg model on the square lattice in a magnetic field, Phys. Rev. B 79, 195102 (2009).
  5. M. Mourigal, M. E. Zhitomirsky, and A. L. Chernyshev, Field-induced decay dynamics in square-lattice antiferromagnets, Phys. Rev. B 82, 144402 (2010).
  6. W. T. Fuhrman, M. Mourigal, M. E. Zhitomirsky, and A. L. Chernyshev, Dynamical structure factor of quasi-two-dimensional antiferromagnet in high fields, Phys. Rev. B 85, 184405 (2012).
  7. M. E. Zhitomirsky and A. L. Chernyshev, Colloquium: Spontaneous magnon decays, Rev. Mod. Phys. 85, 219 (2013).
  8. N. S. Headings, S. M. Hayden, R. Coldea, and T. G. Perring, Anomalous high-energy spin excitations in the high-Tc superconductor-parent antiferromagnet La2CuO4, Phys. Rev. Lett. 105, 247001 (2010).
  9. K. W. Plumb, A. T. Savici, G. E. Granroth, F. C. Chou, and Y.-J. Kim, High-energy continuum of magnetic excitations in the two-dimensional quantum antiferromagnet Sr2CuO2Cl2, Phys. Rev. B 89, 180410(R) (2014).
  10. B. Dalla Piazza, M. Mourigal, N. B. Christensen, G. J. Nilsen, P. Tregenna-Piggott, T. G. Perring, M. Enderle, D. F. McMorrow, D. A. Ivanov, and H. M. Rønnow, Fractional excitations in the square-lattice quantum antiferromagnet, Nat. Phys. 11, 62 (2014).
  11. M. Powalski, G. S. Uhrig, and K. P. Schmidt, Roton minimum as a fingerprint of magnon-Higgs scattering in ordered quantum antiferromagnets, Phys. Rev. Lett. 115, 207202 (2015).
  12. M. Powalski, K. P. Schmidt, and G. S. Uhrig, Mutually attracting spin waves in the square-lattice quantum antiferromagnet, SciPost Phys. 4, 001 (2018).
  13. A. Auerbach and D. P. Arovas, Spin dynamics in the square-lattice antiferromagnet, Phys. Rev. Lett. 61, 617 (1988).
  14. T. C. Hsu, Spin waves in the flux-phase description of the S=1/2 Heisenberg antiferromagnet, Phys. Rev. B 41, 11379 (1990).
  15. C.-M. Ho, V. N. Muthukumar, M. Ogata, and P. W. Anderson, Nature of spin excitations in two-dimensional Mott insulators: Undoped cuprates and other materials, Phys. Rev. Lett. 86, 1626 (2001).
  16. H. Shao, Y. Q. Qin, S. Capponi, S. Chesi, Z. Y. Meng, and A. W. Sandvik, Nearly deconfined spinon excitations in the square-lattice spin-1/2 Heisenberg antiferromagnet, Phys. Rev. X 7, 041072 (2017).
  17. S.-L. Yu, W. Wang, Z.-Y. Dong, Z.-J. Yao, and J.-X. Li, Deconfinement of spinons in frustrated spin systems: Spectral perspective, Phys. Rev. B 98, 134410 (2018).
  18. S.-S. Zhang, E. A. Ghioldi, L. O. Manuel, A. E. Trumper, and C. D. Batista, Schwinger boson theory of ordered magnets, Phys. Rev. B 105, 224404 (2022).
  19. J. B. Fouet, P. Sindzingre, and C. Lhuillier, An investigation of the quantum J1−J2−J3 model on the honeycomb lattice, Eur. Phys. J. B 20, 241 (2001).
  20. A. Mulder, R. Ganesh, L. Capriotti, and A. Paramekanti, Spiral order by disorder and lattice nematic order in a frustrated Heisenberg antiferromagnet on the honeycomb lattice, Phys. Rev. B 81, 214419 (2010).
  21. J. Oitmaa and R. R. P. Singh, Phase diagram of the J1−J2−J3 Heisenberg model on the honeycomb lattice: A series expansion study, Phys. Rev. B 84, 094424 (2011).
  22. D. J. J. Farnell, R. F. Bishop, P. H. Y. Li, J. Richter, and C. E. Campbell, Frustrated Heisenberg antiferromagnet on the honeycomb lattice: A candidate for deconfined quantum criticality, Phys. Rev. B 84, 012403 (2011).
  23. A. F. Albuquerque, D. Schwandt, B. Hetényi, S. Capponi, M. Mambrini, and A. M. Läuchli, Phase diagram of a frustrated quantum antiferromagnet on the honeycomb lattice: Magnetic order versus valence-bond crystal formation, Phys. Rev. B 84, 024406 (2011).
  24. R. Ganesh, J. van den Brink, and S. Nishimoto, Deconfined criticality in the frustrated Heisenberg honeycomb antiferromagnet, Phys. Rev. Lett. 110, 127203 (2013).
  25. Z. Zhu, D. A. Huse, and S. R. White, Weak plaquette valence bond order in the S=1/2 honeycomb J1−J2 Heisenberg model, Phys. Rev. Lett. 110, 127205 (2013).
  26. S.-S. Gong, D. N. Sheng, O. I. Motrunich, and M. P. A. Fisher, Phase diagram of the spin-1/2 J1−J2 Heisenberg model on a honeycomb lattice, Phys. Rev. B 88, 165138 (2013).
  27. E. Ghorbani, F. Shahbazi, and H. Mosadeq, Quantum phase diagram of distorted J1−J2 Heisenberg S=1/2 antiferromagnet in honeycomb lattice: A modified spin wave study, J. Phys. Condens. Matter 28, 406001 (2016).
  28. S. S. Pershoguba, S. Banerjee, J. C. Lashley, J. Park, H. Ågren, G. Aeppli, and A. V. Balatsky, Dirac magnons in honeycomb ferromagnets, Phys. Rev. X 8, 011010 (2018).
  29. P. McClarty, Topological magnons: A review, Annu. Rev. Condens. Matter Phys. 13, 171 (2022).
  30. S. E. Nikitin, B. Fåk, K. W. Krämer, T. Fennell, B. Normand, A. M. Läuchli, and C. Rüegg, Thermal evolution of Dirac magnons in the honeycomb ferromagnet CrBr3, Phys. Rev. Lett. 129, 127201 (2022).
  31. P. A. Maksimov and A. L. Chernyshev, Field-induced dynamical properties of the XXZ model on a honeycomb lattice, Phys. Rev. B 93, 014418 (2016).
  32. F. Ferrari and F. Becca, Dynamical properties of Néel and valence-bond phases in the J1−J2 model on the honeycomb lattice, J. Phys. Condens. Matter 32, 274003 (2020).
  33. C. Gu, S.-L. Yu, and J.-X. Li, Spin dynamics and continuum spectra of the honeycomb J1−J2 antiferromagnetic Heisenberg model, Phys. Rev. B 105, 174403 (2022).
  34. C. Wessler, B. Roessli, K. W. Krämer, B. Delley, O. Waldmann, L. Keller, D. Cheptiakov, H. B. Braun, and M. Kenzelmann, Observation of plaquette fluctuations in the spin-1/2 honeycomb lattice, npj Quantum Mater. 5, 85 (2020).
  35. G. Sala, M. B. Stone, B. K. Rai, A. F. May, P. Laurell, V. O. Garlea, N. P. Butch, M. D. Lumsden, G. Ehlers, G. Pokharel, A. Podlesnyak, D. Mandrus, D. S. Parker, S. Okamoto, G. B. Halász, and A. D. Christianson, Van Hove singularity in the magnon spectrum of the antiferromagnetic quantum honeycomb lattice, Nat. Commun. 12, 171 (2021).
  36. G. Sala, M. B. Stone, G. B. Halász, M. D. Lumsden, A. F. May, D. M. Pajerowski, S. Ohira-Kawamura, K. Kaneko, D. G. Mazzone, G. Simutis, J. Lass, Y. Kato, S.-H. Do, J. Y. Y. Lin, and A. D. Christianson, Field-tuned quantum renormalization of spin dynamics in the honeycomb lattice Heisenberg antiferromagnet YbCl3, Commun. Phys. 6, 234 (2023).
  37. See the Supplemental Material at http://link.aps.org/supplemental/10.1103/q29r-8x1m, which includes Refs. [38–55], for detailed descriptions of our single-crystal sample, our unpolarized and polarized INS experiments, data-analysis procedures, spin-wave fits to the fully polarized spectra, and cylinder MPS calculations.
  38. K. W. Krämer, H. U. Güdel, B. Roessli, P. Fischer, A. Dönni, N. Wada, F. Fauth, M. T. Fernandez-Diaz, and T. Hauss, Noncollinear two- and three-dimensional magnetic ordering in the honeycomb lattices of ErX3 (X= Cl, Br, I), Phys. Rev. B 60, R3724 (1999).
  39. D. Brown, S. Fletcher, and D. G. Holah, The preparation and crystallographic properties of certain lanthanide and actinide tribromides and tribromide hexahydrates, J. Chem. Soc. A 2, 1889 (1968).
  40. L. B. Asprey, T. K. Keenan, and F. H. Kruse, Preparation and crystal data for lanthanide and actinide triiodides, Inorg. Chem. 3, 1137 (1964).
  41. D. H. Templeton and G. F. Carter, The crystal structures of yttrium trichloride and similar compounds, J. Phys. Chem. 58, 940 (1954).
  42. M. F. Collins, Magnetic Critical Scattering (Oxford University Press, New York, 1989).
  43. J. Lass, H. Jacobsen, D. G. Mazzone, and K. Lefmann, MJOLNIR: A software package for multiplexing neutron spectrometers, SoftwareX 12, 100600 (2020).
  44. L. Facheris, K. Y. Povarov, S. D. Nabi, D. G. Mazzone, J. Lass, B. Roessli, E. Ressouche, Z. Yan, S. Gvasaliya, and A. Zheludev, Spin density wave versus fractional magnetization plateau in a triangular antiferromagnet, Phys. Rev. Lett. 129, 087201 (2022).
  45. J. Lass, E. Y. Lenander, K. M. L. Krighaar, T. N. Tošić, D. Prabhakaran, P. P. Deen, S. Holm-Janas, and K. Lefmann, Characterizing the diffuse continuum excitations in the classical spin liquid h−YMnO3, Phys. Rev. B 110, 144429 (2024).
  46. R. M. Moon, T. Riste, and W. C. Koehler, Polarization analysis of thermal-neutron scattering, Phys. Rev. 181, 920 (1969).
  47. A. T. Boothroyd, Principles of Neutron Scattering from Condensed Matter (Oxford University Press, New York, 2020).
  48. A. R. Wildes, Scientific reviews: Neutron polarization analysis corrections made easy, Neutron News 17, 17 (2006).
  49. Sunny.jl, version v0.7.3, software available online at https://github.com/SunnySuite/Sunny.jl.
  50. C. Wessler, Neutron scattering study of the 2D dipolar magnet ErBr3 and the 2D quantum spin liquid system YbBr3, Ph.D. thesis, Universität Basel, 2022.
  51. U. Schollwöck, The density-matrix renormalization group in the age of matrix product states, Ann. Phys. (Amsterdam) 326, 96 (2011).
  52. E. M. Stoudenmire and S. R. White, Studying two-dimensional systems with the density matrix renormalization group, Annu. Rev. Condens. Matter Phys. 3, 111 (2012).
  53. J. Hauschild and F. Pollmann, Efficient numerical simulations with tensor networks: Tensor Network Python (TeNPy), SciPost Phys. Lect. Notes 5, 1 (2018).
  54. M. Popovici, On the resolution of slow-neutron spectrometers. IV. The triple-axis spectrometer resolution function, spatial effects included, Acta Crystallogr. A 31, 507 (1975).
  55. G. Eckold and O. Sobolev, Analytical approach to the 4d-resolution function of three axes neutron spectrometers with focussing monochromators and analysers, Nucl. Instrum. Methods Phys. Res., Sect. A 752, 54 (2014).
  56. J. Lass, H. Jacobsen, K. M. L. Krighaar, D. Graf, F. Groitl, F. Herzog, M. Yamada, C. Kägi, R. A. Müller, R. Bürge, M. Schild, M. S. Lehmann, A. Bollhalder, P. Keller, M. Bartkowiak, U. Filges, U. Greuter, G. Theidel, H. M. Rønnow, C. Niedermayer, and D. G. Mazzone, Commissioning of the novel continuous angle multi-energy analysis spectrometer at the Paul Scherrer Institut, Rev. Sci. Instrum. 94, 023302 (2023).
  57. K. Schmalzl, W. Schmidt, S. Raymond, H. Feilbach, C. Mounier, B. Vettard, and T. Brückel, The upgrade of the cold neutron three-axis spectrometer IN12 at the ILL, Nucl. Instrum. Methods Phys. Res., Sect. A 819, 89 (2016).
  58. M. Gohlke, R. Verresen, R. Moessner, and F. Pollmann, Dynamics of the Kitaev-Heisenberg model, Phys. Rev. Lett. 119, 157203 (2017).
  59. R. Verresen, F. Pollmann, and R. Moessner, Quantum dynamics of the square-lattice Heisenberg model, Phys. Rev. B 98, 155102 (2018).
  60. T. Xie, A. A. Eberharter, J. Xing, S. Nishimoto, M. Brando, P. Khanenko, J. Sichelschmidt, A. A. Turrini, D. G. Mazzone, P. G. Naumov, L. D. Sanjeewa, N. Harrison, A. S. Sefat, B. Normand, A. M. Läuchli, A. Podlesnyak, and S. E. Nikitin, Complete field-induced spectral response of the spin-1/2 triangular-lattice antiferromagnet CsYbSe2, npj Quantum Mater. 8, 48 (2023).
  61. T. Weber, R. Georgii, and P. Böni, takin: An open-source software for experiment planning, visualisation, and data analysis, SoftwareX 5, 121 (2016).
  62. C. A. Pocs, P. E. Siegfried, J. Xing, A. S. Sefat, M. Hermele, B. Normand, and M. Lee, Systematic extraction of crystal electric-field effects and quantum magnetic model parameters in triangular rare-earth magnets, Phys. Rev. Res. 3, 043202 (2021).
  63. M. Oshikawa and I. Affleck, Field-induced gap in S=1/2 antiferromagnetic chains, Phys. Rev. Lett. 79, 2883 (1997).
  64. J. G. Rau and M. J. P. Gingras, Frustration and anisotropic exchange in ytterbium magnets with edge-shared octahedra, Phys. Rev. B 98, 054408 (2018).
  65. R. Verresen, R. Moessner, and F. Pollmann, Avoided quasiparticle decay from strong quantum interactions, Nat. Phys. 15, 750 (2019).
  66. F. Elson, M. Nayak, A. A. Eberharter, M. Skoulatos, S. Ward, N. B. Christensen, D. Voneshen, C. Fiolka, K. W. Krämer, Ch. Rüegg, B. Normand, M. Mourigal, H. M. Rønnow, F. Mila, A. M. Läuchli, and M. Månsson, Field-induced shadow-mode excitations in the square-lattice quantum antiferromagnet CuF2(D2O)2 (pyz) (unpublished).
  67. L. D. Landau, Theory of the superfluidity of helium II, Phys. Rev. 60, 356 (1941).
  68. J. A. Hernández, A. A. Eberharter, O. S. Fjellvag, M. Kenzelmann, K. W. Krämer, A. M. Läuchli, S. Raymond, B. Roessli, and M. Schuler, Investigation of the polarization-dependence of field-induced roton minima in the 2D van der Waals honeycomb antiferromagnet YbBr3, 10.5291/ILL-DATA.CRG-3010 (2022).

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Phys. Rev. Lett. 135, 146701– Published 3 October, 2025
  • Received 23 December 2024
  • Revised 4 July 2025
  • Accepted 24 July 2025
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