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Structural classification of boron nitride twisted bilayers and ab initio investigation of their stacking-dependent electronic structure
by Sylvain Latil, Hakim Amara, Lorenzo Sponza
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Submission summary
| Authors (as registered SciPost users): | Hakim Amara · Lorenzo Sponza |
| Submission information | |
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| Preprint Link: | https://arxiv.org/abs/2206.05845v4 (pdf) |
| Date accepted: | 2022-12-02 |
| Date submitted: | 2022-11-18 09:43 |
| Submitted by: | Sponza, Lorenzo |
| Submitted to: | SciPost Physics |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
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| Approach: | Theoretical |
Abstract
Since the discovery of superconductive twisted bilayer graphene which initiated the field of twistronics, moir\'e systems have not ceased to exhibit fascinating properties. We demonstrate that in boron nitride twisted bilayers, for a given moir\'e periodicity, there are five different stackings which preserve the monolayer hexagonal symmetry (i.e. the invariance upon rotations of 120$^\circ$) and not only two as always discussed in literature. We introduce some definitions and a nomenclature that identify unambiguously the twist angle and the stacking sequence of any hexagonal bilayer with order-3 rotation symmetry. Moreover, we employ density functional theory to study the evolution of the band structure as a function of the twist angle for each of the five stacking sequences of boron nitride bilayers. We show that the gap is indirect at any angle and in any stacking, and identify features that are conserved within the same stacking sequence irrespective of the angle of twist.
List of changes
1) We divided the main text into sections
2) We corrected a wrong reference and added some other relevant works to the reference list.
3) We have clarified the fact that expressing the supercell with the (q,p) pair does not limit the choice of twist angle. We added a new appendix (appendix E) and we referenced to it in the text. In page 2 of the new version we added a sentence to stress that stacking sequence and twist angle are two independent degrees of freedom.
4) We added symmetry group numbers in Table 1 and Figure 11.
5) We detailed better the relation between untwisted bilayers and twisted ones. In page 3 of the new version we added some sentences to point out that the untwisted bilayers can be thought as special cases of a more general scheme and we explained why we haven't added them in Figures 5 and 15 even though they formally fall in the delta=1 family.
6) We stressed further the generality of our derivation.
7) We provided arguments in favour of our statement that hybrid potentials or the GW approximation will not change the indirect nature of the gap. We added some observations on the robustness of the indirect band gap whenever two layers of BN are stacked on top of each other (bulk, bilayers) with appropriate references. We also changed a sentence in page 4 referring to GW and hybrid calculations showing the same indirect gap characteristics.
8) In the Appendix, we specified the exchange correlation potential used
9) We corrected some grammar mistakes.
Published as SciPost Phys. 14, 053 (2023)