Topological metallic phases in spin–orbit coupled bilayer systems

Pan, Hui; Li, Xin; Qiao, Zhenhua; Liu, Cheng-Cheng; Yao, Yugui; Yang, Shengyuan A.

doi:10.1088/1367-2630/16/12/123015

Cited by 22 publications

(23 citation statements)

References 58 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thus, ML-HfGeTe also serves as the first realistic example that realizes the 2D Z 2 topological metal phase proposed in Ref. 55. The nontrivial Z 2 invariant dictates the presence of topological edge states at the sample boundaries 54,57,58 .…”

mentioning

confidence: 73%

Two-dimensional spin-orbit Dirac point in monolayer HfGeTe

Guan

Liu

et al. 2017

Phys. Rev. Materials

Self Cite

View full text Add to dashboard Cite

Dirac points in two-dimensional (2D) materials have been a fascinating subject of research, with graphene as the most prominent example. However, the Dirac points in existing 2D materials, including graphene, are vulnerable against spin-orbit coupling (SOC). Here, based on first-principles calculations and theoretical analysis, we propose a new family of stable 2D materials, the HfGeTefamily monolayers, which represent the first example to host so-called spin-orbit Dirac points (SDPs) close to the Fermi level. These Dirac points are special in that they are formed only under significant SOC, hence they are intrinsically robust against SOC. We show that the existence of a pair of SDPs are dictated by the nonsymmorphic space group symmetry of the system, which are very robust under various types of lattice strains. The energy, the dispersion, and the valley occupation around the Dirac points can be effectively tuned by strain. We construct a low-energy effective model to characterize the Dirac fermions around the SDPs. Furthermore, we find that the material is simultaneously a 2D Z2 topological metal, which possesses nontrivial Z2 invariant in the bulk and spin-helical edge states on the boundary. From the calculated exfoliation energies and mechanical properties, we show that these materials can be readily obtained in experiment from the existing bulk materials. Our result reveals HfGeTe-family monolayers as a promising platform for exploring spin-orbit Dirac fermions and novel topological phases in two-dimensions.

show abstract

mentioning

confidence: 73%

Two-dimensional spin-orbit Dirac point in monolayer HfGeTe

Guan

Liu

et al. 2017

Phys. Rev. Materials

Self Cite

View full text Add to dashboard Cite

show abstract

“…Further investigations [7] pointed out that, mediated by an external electric field, the (PbC 4 H 5 ) 3 lattice presents an energetically stable ferrimagnetic QAH phase. Meanwhile, the recently synthesized Ni 3 (C 18 H 12 N 6 ) 2 MOF [8] can be considered as the experimental realization of the so called topological Z 2 -metallic phase [9] in MOFs. It is characterized by a kagome lattice, with a global energy gap at the edge of the Brillouin zone (K point), whereas the energy dispersion of the flat (kagome band) along the Γ-K direction gives rise to a local gap at the Γ point [10].…”

Section: Introductionmentioning

confidence: 99%

Tuning the topological states in metal-organic bilayers

2017

View full text Add to dashboard Cite

We have investigated the energetic stability and the electronic properties of metal-organic topological insulators bilayers (BLs), (MC4S4)3-BL, with M=Ni and Pt, using first-principles calculations and tight-binding model. Our findings show that (MC4S4)3-BL is an appealing platform to perform electronic band structure engineering, based on the topologically protected chiral edge states. The energetic stability of the BLs is ruled by van der Waals interactions; being the AA stacking the energetically most stable one. The electronic band structure is characterized by a combination of bonding and anti-bonding kagome band sets (KBSs), revealing that (NiC4S4)3-BL presents a Z2-metallic phase, whereas (PtC4S4)3-BL may present both Z2-metallic phase or quantum spin Hall phase. Those non-trivial topological states were confirmed by the formation of chiral edge states in (MC4S4)3-BL nanoribbons. We show that the localization of the edge states can be controlled with a normal external electric field, breaking the mirror symmetry. Hence, the sign of electric field selects in which layer each set of edge states are located. Such a control on the (layer) localization, of the topological edge states, bring us an additional and interesting degree of freedom to control the transport properties in layered metal-organic topological insulator.

show abstract

“…In the research of two-dimensional hexagon lattice, bilayer systems have attracted a lot of attention [24][25][26][27][28][29][30]. The various interlayer interaction between the nearest neighbor of the two layers makes the bilayers possess different properties [31].…”

Section: Introductionmentioning

confidence: 99%

“…1(b) [7,34]. Compared with monolayer system, the extra layer degree of freedom can lead to many new physical phenomenons, and it is also easier to be controlled in experiments [24][25][26]. Besides, in terms of topological properties, bilayer is different from single layer.…”

Section: Introductionmentioning

confidence: 99%

“…A quintessential example should be cited that the bilayer system formed by the combination of two layers of quantum spin Hall insulator becomes a trivial band insulator (BI) [35], but when a bias voltage is introduced, the bilayer system goes over to topologically nontrivial. This indicates that the topological properties of bilayer are quite different from the single [24]. To obtain more concerning two-dimensional hexagon lattice bilayers, by analyzing the changing of Dirac points and topological quantum numbers, we investigate the quantum valley Hall (QVH) state of two-dimensional hexagon lattice bilayers.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation