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Published March 26, 2024 | Published
Journal Article Open

Quantum Barkhausen noise induced by domain wall cotunneling

  • 1. ROR icon California Institute of Technology


Most macroscopic magnetic phenomena (including magnetic hysteresis) are typically understood classically. Here, we examine the dynamics of a uniaxial rare-earth ferromagnet deep within the quantum regime, so that domain wall motion, and the associated hysteresis, is initiated by quantum nucleation, which then grows into large-scale domain wall motion, which is observable as an unusual form of Barkhausen noise. We observe noncritical behavior in the resulting avalanche dynamics that only can be explained by going beyond traditional renormalization group methods or classical domain wall models. We find that this “quantum Barkhausen noise” exhibits two distinct mechanisms for domain wall movement, each of which is quantum-mechanical, but with very different dependences on an external magnetic field applied transverse to the spin (Ising) axis. These observations can be understood in terms of the correlated motion of pairs of domain walls, nucleated by cotunneling of plaquettes (sections of domain wall), with plaquette pairs correlated by dipolar interactions; this correlation is suppressed by the transverse field. Similar macroscopic correlations may be expected to appear in the hysteresis of other systems with long-range interactions.

Copyright and License

© 2024 the Author(s). Published by PNAS. This article is distributed under Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND).


We thank R.D. McKenzie for illuminating discussions. The experimental work and the modeling of the data at Caltech were supported by the U.S. Department of Energy Basic Energy Sciences Award No. DE-SC0014866. Theoretical work at UBC was supported by the National Sciences and Engineering Research Council of Canada, No. RGPIN-2019-05582.


C.S., D.M.S., P.C.E.S., and T.F.R. designed research; C.S. and D.M.S. performed research; C.S., D.M.S., P.C.E.S., and T.F.R. analyzed data; and C.S., D.M.S., P.C.E.S., and T.F.R. wrote the paper.

Data Availability

The datasets underlying the figures in this text are available at the CaltechDATA repository, DOI: https://doi.org/10.22002/n3n50-msf83 (31).

Conflict of Interest

The authors declare no competing interest.


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March 21, 2024
March 29, 2024