- Physical Review Journals
All JournalsPhysics Magazine

Physical Review Research

Reuse & Permissions

It is not necessary to obtain permission to reuse this article or its components as it is available under the terms of the Creative Commons Attribution 4.0 International license. This license permits unrestricted use, distribution, and reproduction in any medium, provided attribution to the author(s) and the published article's title, journal citation, and DOI are maintained. Please note that some figures may have been included with permission from other third parties. It is your responsibility to obtain the proper permission from the rights holder directly for these figures.

Export citation

Export citation

Choose format for download:

Download Citation
  • Letter
  • Open Access

Chiral excitations and the intermediate-field regime in the Kitaev magnet α−RuCl3

Anuja Sahasrabudhe1,*, Mikhail A. Prosnikov2, Thomas C. Koethe1, Philipp Stein1, Vladimir Tsurkan3,4, Alois Loidl3, Markus Grüninger1, Hamoon Hedayat1,†, and Paul H. M. van Loosdrecht1,‡

  • 1Institute of Physics II, University of Cologne, 50937 Cologne, Germany
  • 2High Field Magnet Laboratory (HFML-EMFL), Radboud University, 6525 ED Nijmegen, The Netherlands
  • 3University of Augsburg, 86159 Augsburg, Germany
  • 4Institute of Applied Physics, MD 2028, Chisinau, Republic of Moldova

  • *sahasrabudhe@ph2.uni-koeln.de
  • †hedayat@ph2.uni-koeln.de
  • ‡pvl@ph2.uni-koeln.de
PDF

Phys. Rev. Research 6, L022005 – Published 5 April, 2024

DOI: https://doi.org/10.1103/PhysRevResearch.6.L022005

Abstract

In the Kitaev magnet α-RuCl3, the existence of a magnetic-field-induced quantum spin-liquid phase and of anyonic excitations is controversially discussed. We address this elusive, exotic phase via helicity-dependent Raman scattering and analyze the Raman optical activity of excitations as a function of magnetic field and temperature. The hotly debated field regime between 7.5 and 10.5T is characterized by clear spectroscopic signatures such as a plateau of the Raman optical activity of the dominant, chiral spin-flip excitation. This provides direct evidence for the existence of a distinct intermediate-field regime with an intriguing ground state featuring chiral excitations.

View figure in article

Physics Subject Headings (PhySH)

Article Text

Supplemental Material

References (53)

  1. A. Kitaev, Anyons in an exactly solved model and beyond, Ann. Phys. 321, 2 (2006).
  2. G. Jackeli and G. Khaliullin, Mott insulators in the strong spin-orbit coupling limit: From Heisenberg to a quantum compass and Kitaev models, Phys. Rev. Lett. 102, 017205 (2009).
  3. H.-S. Kim, V. V. Shankar, A. Catuneanu, and H.-Y. Kee, Kitaev magnetism in honeycomb α-RuCl3with intermediate spin-orbit coupling, Phys. Rev. B 91, 241110(R) (2015).
  4. A. Banerjee, J. Yan, J. Knolle, C. A. Bridges, M. B. Stone, M. D. Lumsden, D. G. Mandrus, D. A. Tennant, R. Moessner, and S. E. Nagler, Neutron scattering in the proximate quantum spin liquid α-RuCl3, Science 356, 1055 (2017).
  5. L. J. Sandilands, Y. Tian, K. W. Plumb, Y.-J. Kim, and K. S. Burch, Scattering continuum and possible fractionalized excitations in α-RuCl3, Phys. Rev. Lett. 114, 147201 (2015).
  6. J. Nasu, J. Knolle, D. L. Kovrizhin, Y. Motome, and R. Moessner, Fermionic response from fractionalization in an insulating two-dimensional magnet, Nat. Phys. 12, 912 (2016).
  7. S.-H. Do, S.-Y. Park, J. Yoshitake, J. Nasu, Y. Motome, Y. S. Kwon, D. T. Adroja, D. J. Voneshen, K. Kim, T. H. Jang, J. H. Park, K.-Y. Choi, and S. Ji, Majorana fermions in the Kitaev quantum spin system α-RuCl3, Nat. Phys. 13, 1079 (2017).
  8. S.-H. Baek, S.-H. Do, K.-Y. Choi, Y. S. Kwon, A. U. B. Wolter, S. Nishimoto, J. Van Den Brink, and B. Büchner, Evidence for a field-induced quantum spin liquid in α-RuCl3, Phys. Rev. Lett. 119, 037201 (2017).
  9. R. D. Johnson, S. C. Williams, A. A. Haghighirad, J. Singleton, V. Zapf, P. Manuel, I. I. Mazin, Y. Li, H. O. Jeschke, R. Valentí, and R. Coldea, Monoclinic crystal structure of α-RuCl3and the zigzag antiferromagnetic ground state, Phys. Rev. B 92, 235119 (2015).
  10. H. B. Cao, A. Banerjee, J.-Q. Yan, C. A. Bridges, M. D. Lumsden, D. G. Mandrus, D. A. Tennant, B. C. Chakoumakos, and S. E. Nagler, Low-temperature crystal and magnetic structure of α-RuCl3, Phys. Rev. B 93, 134423 (2016).
  11. A. Banerjee, P. Lampen-Kelley, J. Knolle, C. Balz, A. A. Aczel, B. Winn, Y. Liu, D. Pajerowski, J. Yan, C. A. Bridges et al., Excitations in the field-induced quantum spin liquid state of α-RuCl3, npj Quantum Mater. 3, 8 (2018).
  12. C. Balz, P. Lampen-Kelley, A. Banerjee, J. Yan, Z. Lu, X. Hu, S. M. Yadav, Y. Takano, Y. Liu, D. A. Tennant, M. D. Lumsden, D. Mandrus, and S. E. Nagler, Finite field regime for a quantum spin liquid in α-RuCl3, Phys. Rev. B 100, 060405(R) (2019).
  13. K. A. Modic, R. D. McDonald, J. Ruff, M. D. Bachmann, Y. Lai, J. C. Palmstrom, D. Graf, M. K. Chan, F. Balakirev, J. Betts et al., Scale-invariant magnetic anisotropy in α-RuCl3at high magnetic fields, Nat. Phys. 17, 240 (2021).
  14. J. Wagner, A. Sahasrabudhe, R. B. Versteeg, L. Wysocki, Z. Wang, V. Tsurkan, A. Loidl, D. I. Khomskii, H. Hedayat, and P. H. van Loosdrecht, Magneto-optical study of metamagnetic transitions in the antiferromagnetic phase of α-RuCl3, npj Quantum Mater. 7, 28 (2022).
  15. A. Sahasrabudhe, D. Kaib, S. Reschke, R. German, T. Koethe, J. Buhot, D. Kamenskyi, C. Hickey, P. Becker, V. Tsurkan, A. Loidl, S. H. Do, K. Y. Choi, M. Gruninger, S. M. Winter, Z. Wang, R. Valenti, and P. H. M. van Loosdrecht, High-field quantum disordered state in α-RuCl3: Spin flips, bound states, and multiparticle continuum, Phys. Rev. B 101, 140410(R) (2020).
  16. A. N. Ponomaryov, L. Zviagina, J. Wosnitza, P. Lampen-Kelley, A. Banerjee, J.-Q. Yan, C. A. Bridges, D. G. Mandrus, S. E. Nagler, and S. A. Zvyagin, Nature of magnetic excitations in the high-field phase of α-RuCl3, Phys. Rev. Lett. 125, 037202 (2020).
  17. Z. Wang, S. Reschke, D. Hüvonen, S.-H. Do, K.-Y. Choi, M. Gensch, U. Nagel, T. Rõõm, and A. Loidl, Magnetic excitations and continuum of a possibly field-induced quantum spin liquid in α-RuCl3, Phys. Rev. Lett. 119, 227202 (2017).
  18. Y. Kasahara, T. Ohnishi, Y. Mizukami, O. Tanaka, S. Ma, K. Sugii, N. Kurita, H. Tanaka, J. Nasu, Y. Motome et al., Majorana quantization and half-integer thermal quantum Hall effect in a Kitaev spin liquid, Nature (London) 559, 227 (2018).
  19. T. Yokoi, S. Ma, Y. Kasahara, S. Kasahara, T. Shibauchi, N. Kurita, H. Tanaka, J. Nasu, Y. Motome, C. Hickey et al., Half-integer quantized anomalous thermal Hall effect in the Kitaev material candidate α-RuCl3, Science 373, 568 (2021).
  20. M. Yamashita, J. Gouchi, Y. Uwatoko, N. Kurita, and H. Tanaka, Sample dependence of half-integer quantized thermal Hall effect in the Kitaev spin-liquid candidate α-RuCl3, Phys. Rev. B 102, 220404(R) (2020).
  21. J. Nasu, J. Yoshitake, and Y. Motome, Thermal transport in the Kitaev model, Phys. Rev. Lett. 119, 127204 (2017).
  22. Y. Vinkler-Aviv and A. Rosch, Approximately quantized thermal Hall effect of chiral liquids coupled to phonons, Phys. Rev. X 8, 031032 (2018).
  23. M. Ye, G. B. Halász, L. Savary, and L. Balents, Quantization of the thermal Hall conductivity at small Hall angles, Phys. Rev. Lett. 121, 147201 (2018).
  24. E. Lefrançois, G. Grissonnanche, J. Baglo, P. Lampen-Kelley, J.-Q. Yan, C. Balz, D. Mandrus, S. E. Nagler, S. Kim, Y.-J. Kim, N. Doiron-Leyraud, and L. Taillefer, Evidence of a phonon Hall effect in the Kitaev spin liquid candidate α-RuCl3, Phys. Rev. X 12, 021025 (2022).
  25. P. Czajka, T. Gao, M. Hirschberger, P. Lampen-Kelley, A. Banerjee, J. Yan, D. G. Mandrus, S. E. Nagler, and N. P. Ong, Oscillations of the thermal conductivity in the spin-liquid state of α-RuCl3, Nat. Phys. 17, 915 (2021).
  26. J. A. N. Bruin, R. R. Claus, Y. Matsumoto, N. Kurita, H. Tanaka, and H. Takagi, Robustness of the thermal Hall effect close to half-quantization in α-RuCl3, Nat. Phys. 18, 401 (2022).
  27. S. Gass, P. M. Cônsoli, V. Kocsis, L. T. Corredor, P. Lampen-Kelley, D. G. Mandrus, S. E. Nagler, L. Janssen, M. Vojta, B. Büchner, and A. U. B. Wolter, Field-induced transitions in the Kitaev material α-RuCl3probed by thermal expansion and magnetostriction, Phys. Rev. B 101, 245158 (2020).
  28. S. Bachus, D. A. S. Kaib, Y. Tokiwa, A. Jesche, V. Tsurkan, A. Loidl, S. M. Winter, A. A. Tsirlin, R. Valentí, and P. Gegenwart, Thermodynamic perspective on field-induced behavior of α-RuCl3, Phys. Rev. Lett. 125, 097203 (2020).
  29. R. Schönemann, S. Imajo, F. Weickert, J. Yan, D. G. Mandrus, Y. Takano, E. L. Brosha, P. F. S. Rosa, S. E. Nagler, K. Kindo, and M. Jaime, Thermal and magnetoelastic properties of α-RuCl3in the field-induced low-temperature states, Phys. Rev. B 102, 214432 (2020).
  30. T. T. Mai, A. McCreary, P. Lampen-Kelley, N. Butch, J. R. Simpson, J.-Q. Yan, S. E. Nagler, D. Mandrus, A. R. Hight Walker, and R. V. Aguilar, Polarization-resolved Raman spectroscopy of α-RuCl3and evidence of room-temperature two-dimensional magnetic scattering, Phys. Rev. B 100, 134419 (2019).
  31. A. N. Ponomaryov, E. Schulze, J. Wosnitza, P. Lampen-Kelley, A. Banerjee, J.-Q. Yan, C. A. Bridges, D. G. Mandrus, S. E. Nagler, A. K. Kolezhuk, and S. A. Zvyagin, Unconventional spin dynamics in the honeycomb-lattice material α-RuCl3: High-field electron spin resonance studies, Phys. Rev. B 96, 241107(R) (2017).
  32. D. Wulferding, Y. Choi, S.-H. Do, C. H. Lee, P. Lemmens, C. Faugeras, Y. Gallais, and K.-Y. Choi, Magnon bound states versus anyonic Majorana excitations in the Kitaev honeycomb magnet α-RuCl3, Nat. Commun. 11, 1603 (2020).
  33. J. Knolle, G.-W. Chern, D. L. Kovrizhin, R. Moessner, and N. B. Perkins, Raman scattering signatures of Kitaev spin liquids in A2IrO3 iridates with a=Na or Li, Phys. Rev. Lett. 113, 187201 (2014).
  34. J. Knolle, D. L. Kovrizhin, J. T. Chalker, and R. Moessner, Dynamics of fractionalization in quantum spin liquids, Phys. Rev. B 92, 115127 (2015).
  35. A. Pinczuk, B. S. Dennis, L. N. Pfeiffer, and K. West, Observation of collective excitations in the fractional quantum Hall effect, Phys. Rev. Lett. 70, 3983 (1993).
  36. M. Kang, A. Pinczuk, B. S. Dennis, L. N. Pfeiffer, and K. W. West, Observation of multiple magnetorotons in the fractional quantum Hall effect, Phys. Rev. Lett. 86, 2637 (2001).
  37. A. R. Goñi, A. Pinczuk, J. S. Weiner, B. S. Dennis, L. N. Pfeiffer, and K. W. West, Observation of magnetoplasmons, rotons, and spin-flip excitations in GaAs quantum wires, Phys. Rev. Lett. 70, 1151 (1993).
  38. D. X. Nguyen and D. T. Son, Probing the spin structure of the fractional quantum Hall magnetoroton with polarized Raman scattering, Phys. Rev. Res. 3, 023040 (2021).
  39. S.-F. Liou, F. D. M. Haldane, K. Yang, and E. H. Rezayi, Chiral gravitons in fractional quantum Hall liquids, Phys. Rev. Lett. 123, 146801 (2019).
  40. L. D. Barron, L. Hecht, I. H. McColl, and E. W. Blanch, Raman optical activity comes of age, Mol. Phys. 102, 731 (2004).
  41. See Supplemental Material at http://link.aps.org/supplemental/10.1103/PhysRevResearch.6.L022005 for more experimental details.
  42. C. Chen, X. Chen, B. Deng, K. Watanabe, T. Taniguchi, S. Huang, and F. Xia, Probing interlayer interaction via chiral phonons in layered honeycomb materials, Phys. Rev. B 103, 035405 (2021).
  43. T. Zhang and S. Murakami, Chiral phonons and pseudoangular momentum in nonsymmorphic systems, Phys. Rev. Res. 4, L012024 (2022).
  44. K. Jenni, S. Kunkemöller, W. Schmidt, P. Steffens, A. A. Nugroho, and M. Braden, Chirality of magnetic excitations in ferromagnetic SrRuO3, Phys. Rev. B 105, L180408 (2022).
  45. J. Cenker, B. Huang, N. Suri, P. Thijssen, A. Miller, T. Song, T. Taniguchi, K. Watanabe, M. A. McGuire, D. Xiao et al., Direct observation of two-dimensional magnons in atomically thin CrI3, Nat. Phys. 17, 20 (2021).
  46. R. Hisatomi, A. Noguchi, R. Yamazaki, Y. Nakata, A. Gloppe, Y. Nakamura, and K. Usami, Helicity-changing Brillouin light scattering by magnons in a ferromagnetic crystal, Phys. Rev. Lett. 123, 207401 (2019).
  47. B. Lyu, Y. Gao, Y. Zhang, L. Wang, X. Wu, Y. Chen, J. Zhang, G. Li, Q. Huang, N. Zhang et al., Probing the ferromagnetism and spin wave gap in VI3 by helicity-resolved Raman spectroscopy, Nano Lett. 20, 6024 (2020).
  48. K. R. Hoffman, D. J. Lockwood, and W. M. Yen, Circular dichroism and Raman optical activity in antiferromagnetic transition-metal fluorides, Low Temp. Phys. 31, 786 (2005).
  49. The features M1, M2, and M3 correspond to m1α, m2γ, and m2α in Ref. [15] and to M1, 2M, and 3M in Ref. [32], while M0 corresponds to MB in Ref. [32]. Note that previous data were reported in the I+− [15] and I−+ channels [32]. Due to the pronounced ROA for intermediate fields, not all features are discussed in all previous studies.
  50. We use a base temperature of 1.7K. Via the suppression of the magnon intensity, we estimate the local sample temperature at the laser spot to be TN∼7K at 40µW. Comparing Stokes and anti-Stokes scattering, we find temperature ∼25K at 250µW and ∼41K at 1000µW. See, also, the Supplemental Material [41].
  51. D. G. Joshi, Topological excitations in the ferromagnetic Kitaev-Heisenberg model, Phys. Rev. B 98, 060405(R) (2018).
  52. P. A. McClarty, X.-Y. Dong, M. Gohlke, J. G. Rau, F. Pollmann, R. Moessner, and K. Penc, Topological magnons in Kitaev magnets at high fields, Phys. Rev. B 98, 060404(R) (2018).
  53. L. E. Chern, E. Z. Zhang, and Y. B. Kim, Sign structure of thermal Hall conductivity and topological magnons for in-plane field polarized Kitaev magnets, Phys. Rev. Lett. 126, 147201 (2021).

Outline

Information

Phys. Rev. Research 6, L022005– Published 5 April, 2024
  • Received 4 May 2023
  • Accepted 18 January 2024
Crossmark - Check for updates button
Creative Commons Logo

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.

Published by the American Physical Society

Sign In to Your Journals Account

Filter

Filter

Article Lookup

Enter a citation