---
OA_type: closed access
_id: '22116'
abstract:
- lang: eng
  text: "Magnets with isotropic easy-plane symmetry host Goldstone modes that can
    be leveraged for efficient\r\nspin transport. Here, we present a time-resolved
    optical polarimetry technique that allows us to detect and\r\ncharacterize such
    low-frequency modes, and use it to observe the Goldstone mode in the multi-Q broken
    helix\r\nphase of EuIn2As2. The strength of our technique comes from the ability
    to distinguish between nematic and\r\nmagnetization dynamics in order to yield
    information about the mode structure, in addition to its frequency. We\r\nfind
    that the nearly uniform spin precession characteristic of a Goldstone mode is
    realized only when a small\r\nmagnetic field is used to unpin the broken helix
    from local strain generated during crystal growth. In this regime,\r\nthe mode
    frequency scales linearly with the applied field due to the ground state C2z symmetry
    of the broken\r\nhelix. Our work shows how optical polarimetry can be used to
    study the Goldstone modes of complex magnets."
acknowledgement: "We would like to thank Ehud Altman for helpful discussions. This
  research was primarily funded by the Quantum\r\nMaterials (KC2202) program under
  the U.S. Department of\r\nEnergy, Office of Science, Office of Basic Energy Sciences,\r\nMaterials
  Sciences and Engineering Division under Contract\r\nNo. DE-AC02-05CH11231, which
  supported the experimental and theoretical work at the Lawrence Berkeley National\r\nLaboratory
  and UC Berkeley. D.P. and A.T.B. would like to\r\nacknowledge the Engineering and
  Physical Sciences Research\r\nCouncil, UK and the Oxford- ShanghaiTech collaboration\r\nproject
  for financial support. J.O. received support from\r\nthe Gordon and Betty Moore
  Foundation’s EPiQS Initiative\r\nthrough Grant No. GBMF4537 to J.O. at UC Berkeley.
  V.S.\r\nis supported by the Miller Institute for Basic Research in\r\nScience, UC
  Berkeley. S.J.G. was supported by the Gordon\r\nand Betty Moore Foundation."
article_number: '224401'
article_processing_charge: No
article_type: original
author:
- first_name: A.
  full_name: Liebman-Peláez, A.
  last_name: Liebman-Peláez
- first_name: S. J.
  full_name: Garratt, S. J.
  last_name: Garratt
- first_name: Veronika
  full_name: Sunko, Veronika
  id: 23cb1cf6-2c7a-11ef-91a4-f72fc19f20b3
  last_name: Sunko
  orcid: 0000-0003-2724-3523
- first_name: Y.
  full_name: Sun, Y.
  last_name: Sun
- first_name: J. R.
  full_name: Soh, J. R.
  last_name: Soh
- first_name: D.
  full_name: Prabhakaran, D.
  last_name: Prabhakaran
- first_name: A. T.
  full_name: Boothroyd, A. T.
  last_name: Boothroyd
- first_name: J.
  full_name: Orenstein, J.
  last_name: Orenstein
citation:
  ama: Liebman-Peláez A, Garratt SJ, Sunko V, et al. Observation of a Goldstone mode
    in the broken helix by time-resolved optical polarimetry. <i>Physical Review B</i>.
    2026;113(22). doi:<a href="https://doi.org/10.1103/b48p-kw5l">10.1103/b48p-kw5l</a>
  apa: Liebman-Peláez, A., Garratt, S. J., Sunko, V., Sun, Y., Soh, J. R., Prabhakaran,
    D., … Orenstein, J. (2026). Observation of a Goldstone mode in the broken helix
    by time-resolved optical polarimetry. <i>Physical Review B</i>. American Physical
    Society. <a href="https://doi.org/10.1103/b48p-kw5l">https://doi.org/10.1103/b48p-kw5l</a>
  chicago: Liebman-Peláez, A., S. J. Garratt, Veronika Sunko, Y. Sun, J. R. Soh, D.
    Prabhakaran, A. T. Boothroyd, and J. Orenstein. “Observation of a Goldstone Mode
    in the Broken Helix by Time-Resolved Optical Polarimetry.” <i>Physical Review
    B</i>. American Physical Society, 2026. <a href="https://doi.org/10.1103/b48p-kw5l">https://doi.org/10.1103/b48p-kw5l</a>.
  ieee: A. Liebman-Peláez <i>et al.</i>, “Observation of a Goldstone mode in the broken
    helix by time-resolved optical polarimetry,” <i>Physical Review B</i>, vol. 113,
    no. 22. American Physical Society, 2026.
  ista: Liebman-Peláez A, Garratt SJ, Sunko V, Sun Y, Soh JR, Prabhakaran D, Boothroyd
    AT, Orenstein J. 2026. Observation of a Goldstone mode in the broken helix by
    time-resolved optical polarimetry. Physical Review B. 113(22), 224401.
  mla: Liebman-Peláez, A., et al. “Observation of a Goldstone Mode in the Broken Helix
    by Time-Resolved Optical Polarimetry.” <i>Physical Review B</i>, vol. 113, no.
    22, 224401, American Physical Society, 2026, doi:<a href="https://doi.org/10.1103/b48p-kw5l">10.1103/b48p-kw5l</a>.
  short: A. Liebman-Peláez, S.J. Garratt, V. Sunko, Y. Sun, J.R. Soh, D. Prabhakaran,
    A.T. Boothroyd, J. Orenstein, Physical Review B 113 (2026).
das_tickbox: '1'
dataavailabilitystatement: "The data that support the findings of this article are
  openly\r\navailable [27 -  https://doi.org/10.7910/dvn/rqp3az], embargo periods
  may apply."
date_created: 2026-06-22T08:52:01Z
date_published: 2026-06-01T00:00:00Z
date_updated: 2026-06-24T09:49:27Z
day: '01'
doi: 10.1103/b48p-kw5l
extern: '1'
intvolume: '       113'
issue: '22'
language:
- iso: eng
month: '06'
oa_version: None
publication: Physical Review B
publication_identifier:
  eissn:
  - 2469-9969
  issn:
  - 2469-9950
publication_status: published
publisher: American Physical Society
quality_controlled: '1'
researchdata_availability: yes
status: public
supplementarymaterial: no
title: Observation of a Goldstone mode in the broken helix by time-resolved optical
  polarimetry
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 113
year: '2026'
...