BROWSE

Related Scientist

cces's photo.

cces
강상관계물질연구단
more info

ITEM VIEW & DOWNLOAD

Failure of Nielsen-Ninomiya Theorem and Fragile Topology in Two-Dimensional Systems with Space-Time Inversion Symmetry: Application to Twisted Bilayer Graphene at Magic AngleHighly Cited Paper

DC Field Value Language
dc.contributor.authorJunyeong Ahn-
dc.contributor.authorSungjoon Park-
dc.contributor.authorBohm-Jung Yan-
dc.date.available2019-11-19T11:37:41Z-
dc.date.created2019-06-19-
dc.date.issued2019-04-
dc.identifier.issn2160-3308-
dc.identifier.urihttps://pr.ibs.re.kr/handle/8788114/6537-
dc.description.abstractWe show that the Wannier obstruction and the fragile topology of the nearly flat bands in twisted bilayer graphene at magic angle are manifestations of the nontrivial topology of two-dimensional real wave functions characterized by the Euler class. To prove this, we examine the generic band topology of two-dimensional real fermions in systems with space-time inversion I-ST symmetry. The Euler class is an integer topological invariant classifying real two-band systems. We show that a two-band system with a nonzero Euler class cannot have an I-ST -symmetric Wannier representation. Moreover, a two-band system with the Euler class e(2) has band crossing points whose total winding number is equal to 2e(2). Thus the conventional Nielsen-Ninomiya theorem fails in systems with a nonzero Euler class. We propose that the topological phase transition between two insulators carrying distinct Euler classes can be described in terms of the pair creation and annihilation of vortices accompanied by winding number changes across Dirac strings. When the number of bands is bigger than two, there is a Z(2) topological invariant classifying the band topology, that is, the second Stiefel Whitney class (w(2)). Two bands with an even (odd) Euler class turn into a system with w(2) = 0 (w(2) = 1) when additional trivial bands are added. Although the nontrivial second Stiefel-Whitney class remains robust against adding trivial bands, it does not impose a Wannier obstruction when the number of bands is bigger than two. However, when the resulting multiband system with the nontrivial second Stiefel-Whitney class is supplemented by additional chiral symmetry, a nontrivial second-order topology and the associated corner charges are guaranteed. C. Published by the American Physical Society-
dc.description.uri1-
dc.language영어-
dc.publisherAMER PHYSICAL SOC-
dc.titleFailure of Nielsen-Ninomiya Theorem and Fragile Topology in Two-Dimensional Systems with Space-Time Inversion Symmetry: Application to Twisted Bilayer Graphene at Magic Angle-
dc.typeArticle-
dc.type.rimsART-
dc.identifier.wosid000465181300001-
dc.identifier.scopusid2-s2.0-85065497016-
dc.identifier.rimsid68541-
dc.contributor.affiliatedAuthorJunyeong Ahn-
dc.contributor.affiliatedAuthorSungjoon Park-
dc.contributor.affiliatedAuthorBohm-Jung Yan-
dc.identifier.doi10.1103/PhysRevX.9.021013-
dc.identifier.bibliographicCitationPHYSICAL REVIEW X, v.9, no.2, pp.021013-
dc.citation.titlePHYSICAL REVIEW X-
dc.citation.volume9-
dc.citation.number2-
dc.citation.startPage021013-
dc.description.journalClass1-
dc.description.journalRegisteredClassscie-
dc.description.journalRegisteredClassscopus-
Appears in Collections:
Center for Correlated Electron Systems(강상관계 물질 연구단) > 1. Journal Papers (저널논문)
Files in This Item:
Failure of Nielsen-Ninomiya Theorem and Fragile Topology in Two-Dimensional Systems with Space-Time Inversion Symmetry.pdfDownload

qrcode

  • facebook

    twitter

  • Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.
해당 아이템을 이메일로 공유하기 원하시면 인증을 거치시기 바랍니다.

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

Browse