# Transport signature of the magnetic Berezinskii-Kosterlitz-Thouless transition

### Submission summary

 As Contributors: Suk Bum Chung Preprint link: scipost_202102_00030v1 Date accepted: 2021-03-05 Date submitted: 2021-02-22 10:29 Submitted by: Chung, Suk Bum Submitted to: SciPost Physics Academic field: Physics Specialties: Condensed Matter Physics - Theory Statistical and Soft Matter Physics Approach: Theoretical

### Abstract

Motivated by recent experimental progress in 2D magnetism, we theoretically study spin transport in 2D easy-plane magnets at finite temperatures across the Berezinskii-Kosterlitz-Thouless (BKT) phase transition, by developing a duality mapping to the 2+1D electromagnetism with the full account of spin's finite lifetime. In particular, we find that the non-conservation of spin gives rise to a distinct signature across the BKT transition, with the spin current decaying with distance power-law (exponentially) below (above) the transition; this is detectable in the proposed experiment with NiPS$_3$ and CrCl$_3$.

Published as SciPost Phys. 10, 068 (2021)

We would like to thank both Referees for their constructive and appreciative comments.
We have made all the requested changes, as we are listing below.

### List of changes

1. We have added in Introduction the new references to the recent CrCl3 experiment and the thin film melting transition experiments.

2. We have addressed the terminology issue in the sentence of Eq 4.

3. We have added to the footnote of Eq 4a an explanation on how the Rayleigh dissipation term gives rise to the finite spin lifetime.

4. In the caption to Fig 2, we have added a mention of temperature window where the free meron density follows the BKT formula, and we have revised Fig 2 itself so that all curves are plotted for temperature sufficiently close to T_BKT.

5. We have added a footnote to the penultimate sentence of Conclusion to note a case where the in-plane anisotropy does not
qualitatively affect the BKT transition.