Designer meron lattice on the surface of a topological insulator

Guerci, Daniele; Wang, Jie; Pixley, J. H.; Cano, Jennifer

doi:10.1103/physrevb.106.245417

Cited by 15 publications

(7 citation statements)

References 94 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…So far, band topology in the moiré systems has appeared in the electronic structure of magic angle graphene 16,17 , Chern bands in twisted topological insulators 18 , and topological superconductivity in twisted cuprates 19 . The polar meron-antimeron network suggests that moiré materials also exhibit real space topology, echoing recent similar discoveries of topologically nontrivial strain fields in twisted bilayers 20 and magnetic textures in moiré patterned topological insulators 21 .…”

supporting

confidence: 58%

Polar meron-antimeron networks in strained and twisted bilayers

et al. 2023

View full text Add to dashboard Cite

Out-of-plane polar domain structures have recently been discovered in strained and twisted bilayers of inversion symmetry broken systems such as hexagonal boron nitride. Here we show that this symmetry breaking also gives rise to an in-plane component of polarization, and the form of the total polarization is determined purely from symmetry considerations. The in-plane component of the polarization makes the polar domains in strained and twisted bilayers topologically non-trivial, forming a network of merons and antimerons (half-skyrmions and half-antiskyrmions). For twisted systems, the merons are of Bloch type whereas for strained systems they are of Néel type. We propose that the polar domains in strained or twisted bilayers may serve as a platform for exploring topological physics in layered materials and discuss how control over topological phases and phase transitions may be achieved in such systems.

show abstract

supporting

confidence: 58%

Polar meron-antimeron networks in strained and twisted bilayers

et al. 2023

View full text Add to dashboard Cite

show abstract

“…In a comparable scenario, the phase appeared close to the van Hove energy of a topologically trivial band at relatively weak interactions in an effective moiré-scale Hubbard model for transition metal dichalcogenides [29]. Weak repulsive interactions close to van Hove singularities were also found to promote the emergence of a related topological magnetic texture, called the meron lattice, upon imposing a superlattice potential on the surface of a topological insulator with strong spin-orbit coupling [30]. Con-versely, we establish the importance of this non-coplanar spin texture to the strong-coupling regime of half-integer filled topological flat bands in the absence of spin-orbit coupling of the continuum model of TDBG and TMBG.…”

Section: Introductionmentioning

confidence: 84%

Non-coplanar magnetism, topological density wave order and emergent symmetry at half-integer filling of moiré Chern bands

et al. 2023

View full text Add to dashboard Cite

Twisted double- and mono-bilayer graphene are graphene-based moiré materials hosting strongly correlated fermions in a gate-tunable conduction band with a topologically non-trivial character. Using unbiased exact diagonalization complemented by unrestricted Hartree-Fock calculations, we find that the strong electron-electron interactions lead to a non-coplanar magnetic state, which has the same symmetries as the tetrahedral antiferromagnet on the triangular lattice and can be thought of as a skyrmion lattice commensurate with the moiré scale, competing with a set of ferromagnetic, topological charge density waves featuring an approximate emergent O(3) symmetry, “rotating” the different charge density wave states into each other. Direct comparison with exact diagonalization reveals that the ordered phases are accurately described within the unrestricted Hartree-Fock approximation. Exhibiting a finite charge gap and Chern number |C|=1, the formation of charge density wave order which is intimately connected to a skyrmion lattice phase is consistent with recent experiments on these systems.

show abstract

“…Accordingly, our Kondo-lattice construction and the results for the quasiparticle formation and destruction readily apply in this case. Second, by emphasizing the interplay and coupling between the flat and wide bands, our work brings out an analogy between the correlated quantum materials that host topological flat bands (10-12, 15, 22, 23) and moiré systems (37)(38)(39)(40), in which the strange-metal behavior has also been indicated (26). Compared to the topology of the graphene-based moiré flat bands (38,47), the bands in our case share the traits of being topological but have the distinction of being much simpler.…”

Section: Discussionmentioning

confidence: 99%

“…Thus, our work provides a conceptual framework to address the aforementioned strange-metal behavior in the flat band-based metals. The connection with a Kondolattice description is also being pursued in moiré systems (37)(38)(39)(40). The approach taken here is expected to shed light on the quantum phases and their transitions in those systems.…”

Section: Introductionmentioning

confidence: 99%

Coupled topological flat and wide bands: Quasiparticle formation and destruction

2023

Sci. Adv.

View full text Add to dashboard Cite

Flat bands amplify correlation effects and are of extensive current interest. They provide a platform to explore both topology in correlated settings and correlation physics enriched by topology. Recent experiments in correlated kagome metals have found evidence for strange-metal behavior. A major theoretical challenge is to study the effect of local Coulomb repulsion when the band topology obstructs a real-space description. In a variant to the kagome lattice, we identify an orbital-selective Mott transition in any system of coupled topological flat and wide bands. This was made possible by the construction of exponentially localized and Kramers-doublet Wannier functions, which, in turn, leads to an effective Kondo-lattice description. Our findings show how quasiparticles are formed in such coupled topological flat-wide band systems and, equally important, how they are destroyed. Our work provides a conceptual framework for the understanding of the existing and emerging strange-metal properties in kagome metals and beyond.

show abstract

Designer meron lattice on the surface of a topological insulator

Cited by 15 publications

References 94 publications

Polar meron-antimeron networks in strained and twisted bilayers

Polar meron-antimeron networks in strained and twisted bilayers

Non-coplanar magnetism, topological density wave order and emergent symmetry at half-integer filling of moiré Chern bands

Coupled topological flat and wide bands: Quasiparticle formation and destruction

Contact Info

Product

Resources

About