Observation of a Goldstone mode in the broken helix by time-resolved optical polarimetry
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.
Download
No fulltext has been uploaded. References only!
Journal Article
| Published
| English
Author
Liebman-Peláez, A.;
Garratt, S. J.;
Sunko, VeronikaISTA 
;
Sun, Y.;
Soh, J. R.;
Prabhakaran, D.;
Boothroyd, A. T.;
Orenstein, J.
;
Sun, Y.;
Soh, J. R.;
Prabhakaran, D.;
Boothroyd, A. T.;
Orenstein, J.Abstract
Magnets with isotropic easy-plane symmetry host Goldstone modes that can be leveraged for efficient
spin transport. Here, we present a time-resolved optical polarimetry technique that allows us to detect and
characterize such low-frequency modes, and use it to observe the Goldstone mode in the multi-Q broken helix
phase of EuIn2As2. The strength of our technique comes from the ability to distinguish between nematic and
magnetization dynamics in order to yield information about the mode structure, in addition to its frequency. We
find that the nearly uniform spin precession characteristic of a Goldstone mode is realized only when a small
magnetic field is used to unpin the broken helix from local strain generated during crystal growth. In this regime,
the mode frequency scales linearly with the applied field due to the ground state C2z symmetry of the broken
helix. Our work shows how optical polarimetry can be used to study the Goldstone modes of complex magnets.
Publishing Year
Date Published
2026-06-01
Journal Title
Physical Review B
Publisher
American Physical Society
Acknowledgement
We would like to thank Ehud Altman for helpful discussions. This research was primarily funded by the Quantum
Materials (KC2202) program under the U.S. Department of
Energy, Office of Science, Office of Basic Energy Sciences,
Materials Sciences and Engineering Division under Contract
No. DE-AC02-05CH11231, which supported the experimental and theoretical work at the Lawrence Berkeley National
Laboratory and UC Berkeley. D.P. and A.T.B. would like to
acknowledge the Engineering and Physical Sciences Research
Council, UK and the Oxford- ShanghaiTech collaboration
project for financial support. J.O. received support from
the Gordon and Betty Moore Foundation’s EPiQS Initiative
through Grant No. GBMF4537 to J.O. at UC Berkeley. V.S.
is supported by the Miller Institute for Basic Research in
Science, UC Berkeley. S.J.G. was supported by the Gordon
and Betty Moore Foundation.
Volume
113
Issue
22
Article Number
224401
ISSN
eISSN
IST-REx-ID
Cite this
Liebman-Peláez A, Garratt SJ, Sunko V, et al. Observation of a Goldstone mode in the broken helix by time-resolved optical polarimetry. Physical Review B. 2026;113(22). doi:10.1103/b48p-kw5l
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. Physical Review B. American Physical Society. https://doi.org/10.1103/b48p-kw5l
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.” Physical Review B. American Physical Society, 2026. https://doi.org/10.1103/b48p-kw5l.
A. Liebman-Peláez et al., “Observation of a Goldstone mode in the broken helix by time-resolved optical polarimetry,” Physical Review B, vol. 113, no. 22. American Physical Society, 2026.
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.
Liebman-Peláez, A., et al. “Observation of a Goldstone Mode in the Broken Helix by Time-Resolved Optical Polarimetry.” Physical Review B, vol. 113, no. 22, 224401, American Physical Society, 2026, doi:10.1103/b48p-kw5l.
Google Scholar