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Berezinskii-Kosterlitz-Thouless transition transport in spin-triplet superconductor
by Suk Bum Chung, Se Kwon Kim
This Submission thread is now published as
Submission summary
| Authors (as registered SciPost users): | Suk Bum Chung |
| Submission information | |
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| Preprint Link: | scipost_202109_00016v1 (pdf) |
| Date accepted: | 2021-11-09 |
| Date submitted: | 2021-09-13 19:44 |
| Submitted by: | Chung, Suk Bum |
| Submitted to: | SciPost Physics |
| Ontological classification | |
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| Academic field: | Physics |
| Specialties: |
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| Approach: | Theoretical |
Abstract
As the spin-triplet superconductivity arises from the condensation of spinful Cooper pairs, its full characterization requires not only charge ordering, but also spin ordering. For a two-dimensional (2D) easy-plane spin-triplet superconductor, this naively seems to suggest the possibility of two distinct Berezinskii-Kosterlitz-Thouless (BKT) phase transitions, one in the charge sector and the other in the spin sector. However, it has been recognized that there are actually three possible BKT transitions, involving the deconfinement of, respectively, the conventional vortices, the merons and the half-quantum vortices with vorticity in both the charge and the spin current. By considering equal-spin-pairing spin-triplet superconductors with bulk spin degeneracy, we show how all the transitions can be characterized by the relation between the voltage drop and the spin-polarized current bias. This study reveals that, due to the hitherto unexamined transport of half-quantum vortices, there is an upper bound on the spin supercurrent in a quasi-long range ordered spin-triplet superconductor, which provides a means for half-quantum vortex detection via transport measurements and deeper understanding of fluctuation effects in superconductor-based spintronic devices.
Author comments upon resubmission
We appreciate comments and valuable queries from both Referees, which have helped us improve the clarity and quality of our manuscript. Our response to their reports have given detailed point-by-point responses to all the questions and suggestions. The corresponding modifications are incorporated in the revised manuscript (highlighted in red), which we are listing below.
We believe that our manuscript has been improved sufficiently for publication in SciPost Physics.
With best regards,
Suk Bum Chung and Se Kwon Kim
List of changes
Summary of changes:
• Revision of the introduction to elaborate the motivation behind our work and to specify the types of superconductors considered in our work.
• Revision of Sec. 2 General considerations to discuss the property of half-quantum vortices and to elaborate how three types of the BKT transitions temperatures are derived.
• Revision of the sentences of Eqs. (2), (3), (4), (7), (8), (9) and addition of an extra step each for Eqs. (6) and (8) for better guidance to the equation derivation, as suggested by Referee 1
• Addition of Fig. 4, schematic plots of our main results as suggested by Referee 1
• Addition of Appendix A to discuss the derivation of Eq. (5) as suggested by Referee 1
Published as SciPost Phys. Core 5, 003 (2022)
Reports on this Submission
Report #2 by Anonymous (Referee 1) on 2021-10-17 (Invited Report)
- Cite as: Anonymous, Report on arXiv:scipost_202109_00016v1, delivered 2021-10-17, doi: 10.21468/SciPost.Report.3692
Report
I thank the authors for replying to all my comments. However, while I definitely think this manuscript deserves publication in SciPost, I would rather recommend its publication in SciPost Physics Core rather than SciPost Physics. The specific reason for this assessment is given below.
The main new result is the consequence to transport measurements of the phase diagram involving three BKT transitions. In this regard I still find the reply of the authors regarding the origin of the BKT critical temperatures not satisfactory. One actually determines in a BKT transition is the critical value of the ratio between the stiffness and the temperature. This defines one of the coupling constants in the problem. The most technically correct way to determine the critical couplings would be via a renormalization group analysis where the critical temperatures arise as fixed points. The authors of Ref. 41 at least make a brief discussion of the RG analysis, but without providing details. Details on such a calculation are indeed given in Ref. 54 cited by the authors. The authors should at least have commented further on that, since their phase diagram and fixed point structure essentially follows from the results of Ref. 54. For this reason, as far as the phase structure is concerned, there is no actual novelty here. However, granted that the main aim of the authors was not to analyze the phase structure of the model, but rather to provide results for spin transport in the system, this is not really decisive to bar publication in SciPost Physics. The manuscript clearly fulfills the general acceptance criteria. It remains to judge whether the transport-related results warrant the four expected criteria of publication in SciPost Core. I think it is safe to exclude expectations 1 and 2, since there is neither a groundbreaking theoretical discovery being made nor a breakthrough "on a previously-identified and long-standing research stumbling block". I also don't see expectation 4 being fulfilled either, so it remains to asses whether expectation 3, "open a new pathway in an existing or a new research direction, with clear potential for multipronged follow-up work", is fulfilled by this submission. The authors have derived some useful results for the magnetoresistance in connection to the BKT phase structure, but in my view it is unlikely to really "open a new pathway in an existing or a new research direction".
In summary, I would strongly recommend the publication of this manuscript in SciPost Physics Core. In my view the manuscript does not fulfill the criteria for publication in SciPost Physics.