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Faraday rotation and transmittance as markers of topological phase transitions in 2D materials
by Manuel Calixto, Alberto Mayorgas, Nicolás A. Cordero, Elvira Romera, Octavio Castaños
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Submission summary
| Authors (as registered SciPost users): | Manuel Calixto · Nicolas A. Cordero · Alberto Mayorgas · Elvira Romera |
| Submission information | |
|---|---|
| Preprint Link: | https://arxiv.org/abs/2305.14923v1 (pdf) |
| Date submitted: | 2023-05-31 10:23 |
| Submitted by: | Calixto, Manuel |
| Submitted to: | SciPost Physics |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
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| Approaches: | Experimental, Computational |
Abstract
We analyze the magneto-optical conductivity (and related magnitudes like transmittance and Faraday rotation of the irradiated polarized light) of some elemental two-dimensional Dirac materials of group IV (graphene analogues, buckled honeycomb lattices, like silicene, germanene, stannane, etc.), group V (phosphorene), and zincblende heterostructures (like HgTe/CdTe quantum wells) near the Dirac and gamma points, under out-of-plane magnetic and electric fields, to characterize topological-band insulator phase transitions and their critical points. We provide plots of the Faraday angle and transmittance as a function of the polarized light frequency, for different external electric and magnetic fields, chemical potential, HgTe layer thickness and temperature, to tune the material magneto-optical properties. We have shown that absortance/transmittance acquires extremal values at the critical point, where the Faraday angle changes sign, thus providing fine markers of the topological phase transition.
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Reports on this Submission
Anonymous Report 2 on 2023-9-12 (Invited Report)
- Cite as: Anonymous, Report on arXiv:2305.14923v1, delivered 2023-09-12, doi: 10.21468/SciPost.Report.7810
Report
In the manuscript by Calixto et al., they present a study of the finite frequency conductivity of 2D Dirac materials under a perpendicular magnetic field. Using a generalized model for the low energy Hamiltonian and adjusting the parameters of the general model, they characterize the topological-band insulator phase transition by studying the conductivity, the transmittance, and the corresponding Faraday rotation of different Dirac materials: Silicene, Germanene, HgTe/CdTe quantum wells, and Phosphorene.
The paper is well-written, the methods seem correct, and the results are sound and relevant. Therefore, I recommend the manuscript publication.
Requested changes
Nevertheless, I suggest the authors:
Establish better which of their results are new contributions and which are a review of previous results.
Include a comparison of the typical plot for Landau levels for all cases studied, perhaps in the supplementary.
Better characterized the effect of temperature in least one of the models.
Anonymous Report 1 on 2023-9-9 (Invited Report)
- Cite as: Anonymous, Report on arXiv:2305.14923v1, delivered 2023-09-09, doi: 10.21468/SciPost.Report.7785
Strengths
1 - Well-written
2 - Nice amount of details
3 - Significant research topic
Weaknesses
1 - Needs to improve novelty appealing
2 - Missing citation to recent/important works in the field
Report
Dear editor, below is my report on the manuscript "Faraday rotation and transmittance as markers of topological phase transitions in 2D materials" by M. Calixto, A. Mayorgas, N. A. Cordero, E. Romera, O. Castaños.
In the manuscript, the authors have done an extensive investigation on the magneto-optical properties of different 2D materials. The main claim of the manuscript is to use Faraday rotation and transmittance as possible
markers of topological phase transition (TPT) in the 2D materials. In fact, the reported results show clear signals of TPT in the transmittance (a minimum "peak" value) and in the Faraday rotation (a change of angle sign
with a noticeable peak). Even for the case of non-topological material (phosphorene), a minimum in the transmittance is observed, however associated to the energy gap closing by an external electric field. The manuscript is will written with interesting results and with detailed calculations. However, I have some points that I suggest the authors to revise before further consideration for publication.
Requested changes
1 - The use of magneto-optical effects (linear and also nonlinear optical phenomenon, such as Inverse Faraday Effect) to characterize topological materials have been explored in several previous studies (including Weyl semi-metals), such as: Wu et. al. Science, Vol 354, Issue 6316 pp. 1124-1127 (2016); Ardakani et. al. J. of the Opt. Soc. of Am. B Vol. 38, 9, pp. 2562-2569 (2021); Liang et. al. Opt. Exp. Vol. 28, 17, pp. 24560-24567 (2020); Shao et. al. Nano Lett. 2017, 17, 2, 980–984 (2016); Tokman et. al. Phys. Rev. B 101, 174429 (2020); Shah et. al. Phys. Rev. B 107, 235115 (2023) among many others to cite. In the view of these previous works, it is noticeable that the TPT influences the magneto-optical response, as it is also explored in this present work. Therefore, I suggest the author to give further novel appealing in the Introduction section, so it makes clear why this work would be a "new addition" to the current understanding of TPT signatures on the transmittance and magneto-optical effects.
2 - The results are only for particular direction of magnetic field (perpendicular magnetic field). I believe that an in-plane magnetic field would also be relevant in the context of anisotropy. Therefore, I would suggest the authors to investigate the cases of in-plane for further completeness of the work.
3 - In the beginning of Section II.A, the authors stated that pristine graphene exhibit zero intrinsinc spin-orbit coupling. I agree that it is quite small, specially when compared to the other "heavier" Xenes, with values in the order of \mu eV. However, is not precisely zero, and from the seminal works by Kane and Mele [Phys. Rev. Lett. 95, 226801 (2005) and Phys. Rev. Lett. 95, 226801 (2005)] is also a second-neighbors hopping term, and crucially important to demonstrate the Quantum Spin Hall Effect in graphene.
4 - When showing the results for the phospherene, there is an "important unseen" phenomena which according to the authors does not happen in others 2D materials (just before the section Conclusions). However, there is no proper explanation for this novel phenomena. Therefore, a follow up question is what is the physical origin of this phenomena?