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Evidence of $φ$0-Josephson junction from skewed diffraction patterns in Sn-InSb nanowires
by B. Zhang, Z. Li, V. Aguilar, P. Zhang, M. Pendharkar, C. Dempsey, J. S. Lee, S. D. Harrington, S. Tan, J. S. Meyer, M. Houzet, C. J. Palmstrom, S. M. Frolov
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Submission summary
| Authors (as registered SciPost users): | Sergey Frolov · Bomin Zhang · Po Zhang |
| Submission information | |
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| Preprint Link: | https://arxiv.org/abs/2212.00199v4 (pdf) |
| Code repository: | https://zenodo.org/records/7374094 |
| Data repository: | https://zenodo.org/records/7374094 |
| Date submitted: | 2024-06-08 23:07 |
| Submitted by: | Zhang, Bomin |
| Submitted to: | SciPost Physics |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
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| Approaches: | Experimental, Phenomenological |
Abstract
We study Josephson junctions based on InSb nanowires with Sn shells. We observe skewed critical current diffraction patterns: the maxima in forward and reverse current bias are at different magnetic flux, with a displacement of 20-40 mT. The skew is greatest when the external field is nearly perpendicular to the nanowire, in the substrate plane. This orientation suggests that spin-orbit interaction plays a role. We develop a phenomenological model and perform tight-binding calculations, both methods reproducing the essential features of the experiment. The effect modeled is the $\phi$0-Josephson junction with higher-order Josephson harmonics. The system is of interest for Majorana studies: the effects are either precursor to or concomitant with topological superconductivity. Current-phase relations that lack inversion symmetry can also be used to design quantum circuits with engineered nonlinearity.
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List of changes
Delete sentence from the main text: "Using realistic junction parameters, the numerical model is capable of reproducing the key experimental observations. ", which is a too strong claim.
Modified eqaution in the main text , from $I_{1}, I_{2} \propto (1-{B}/{B_c}^{2})$ to $I_{1}, I_{2} \propto (1-{B}^{2}/{B_c}^{2})$. The original equation has a typo.
Current status:
Reports on this Submission
Report
The authors have responded to my previous comments, but they have not addressed the clarifications I requested regarding the difference between Phi0 behavior and asymmetric CPR, nor have they addressed my criticism on the phenomenological model. Arguments based on authority, such as "Some of us have worked for many years on trying to unambiguously establish the Phi0 behavior" or personal preference, such as "Some of us find the Phi0 effect more interesting than SDE" do not adequately address my comments. I find that the authors are not being sufficiently receptive to my constructive feedback. Thus, after two refereeing rounds, I still cannot recommend publication of the manuscript in the present form but leave the final decision to the editors.
Recommendation
Ask for major revision
Report #1 by Antonio Manesco (Referee 1) on 2024-6-21 (Invited Report)
Report
The referee's addressed most of my criticism, except for choosing their "preferred interpretation" for the origin of the $\phi_0$ effect. Particularly, I would like to refer to [Davydova et al., Sci. Adv. 8, eabo0309 (2022)], where the authors propose a purely orbital origin for the anomalous Josephson effect. I expect this contribution to also depend on the direction of the magnetic field. Moreover, a recent work [Reinhardt, S., Ascherl, T., Costa, A. et al. Nat Commun 15, 4413 (2024)] argues that whereas an anomalous Josephson effect caused by SOC has a strong gate dependence, the orbital counterpart is mostly insensitive to the gate voltage. Since the authors claim that "effect is observed over wide ranges of gate voltage" and that "no consistent effect of gate voltage on the skew magnitude is observed", their observations seem consistent with orbital effects. Thus, it remains unclear to me why the authors "do not feel it [orbital effect] is a significant enough effect to change our preferred interpretation".
I am keen to recommend the manuscript for publication if the authors provide enough data to justify their preferred explanation or give appropriate weight for alternative explanations.
Recommendation
Ask for minor revision