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Magnetism of magic-angle twisted bilayer graphene

by Javad Vahedi, Robert Peters, Ahmed Missaoui, Andreas Honecker, Guy Trambly de Laissardière

Submission summary

As Contributors: Andreas Honecker · Guy Trambly de Laissardière
Arxiv Link: https://arxiv.org/abs/2104.10694v2 (pdf)
Date accepted: 2021-09-02
Date submitted: 2021-08-18 07:54
Submitted by: Honecker, Andreas
Submitted to: SciPost Physics
Academic field: Physics
Specialties:
  • Condensed Matter Physics - Theory
  • Condensed Matter Physics - Computational
Approaches: Theoretical, Computational

Abstract

We investigate magnetic instabilities in charge-neutral twisted bilayer graphene close to so-called "magic angles" using a combination of real-space Hartree-Fock and dynamical mean-field theories. In view of the large size of the unit cell close to magic angles, we examine a previously proposed rescaling that permits to mimic the same underlying flat minibands at larger twist angles. We find that localized magnetic states emerge for values of the Coulomb interaction $U$ that are significantly smaller than what would be required to render an isolated layer antiferromagnetic. However, this effect is overestimated in the rescaled system, hinting at a complex interplay of flatness of the minibands close to the Fermi level and the spatial extent of the corresponding localized states. Our findings shed new light on perspectives for experimental realization of magnetic states in charge-neutral twisted bilayer graphene.

Published as SciPost Phys. 11, 083 (2021)



Author comments upon resubmission

See replies to Reports for Submission 2104.10694v1 on 23 April 2021.

List of changes

1) Content of the sentence "Note that Ref. [40] suggested that the on-site Coulomb interaction should scale in the same way as the intralayer hopping parameters, $U' = \Lambda\,U$" moved from the beginning of section 5 to section 3.
2) Replaced Fig. 2(b), and cleaned up the related discussion of decoupled layers.
3) Added a "the range" to the DMFT critical value of $U$ in the second paragraph of section 4.2.
4) Added "Lines are guides to the eye" to the caption of Fig 4 and "thus limiting DMFT not only to the rescaled system, but also the number of $U$-values considered" at the end of the second paragraph of section 4.2.
5) Fixed aspect ratio of Fig. 1(a) and removed unnecessary reference to moiré length.
6) Outlier specification for Fig. 2(b) corrected to $U/t_0'=2.4$.
7) Updated references.
8) Added two references (new Refs. [18,54]).


Reports on this Submission

Anonymous Report 2 on 2021-8-19 (Invited Report)

Report

The authors have satisfactorily answered all my questions and made relevant changes in the revised version of the manuscript. Therefore I recommend publication in SciPost without further modifications.

  • validity: -
  • significance: -
  • originality: -
  • clarity: -
  • formatting: -
  • grammar: -

Anonymous Report 1 on 2021-8-19 (Invited Report)

Report

I have read the all reviewer reports and comments, the revised manuscript and the replies to the reviewers’ comments. I found that the authors replied the comments and revised the manuscript accordingly, which is improved signifacantly.

In conclusion, I would recommend publishing this manuscript on the SciPost.

  • validity: -
  • significance: -
  • originality: -
  • clarity: -
  • formatting: -
  • grammar: -

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