Two-dimensional obstructed atomic insulators with fractional corner charge in the 
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Wang, Lei; Jiang, Yi; Liu, Jiaxi; Zhang, Shuai; Li, Jiangxu; Liu, Peitao; Sun, Yan; Weng, Hongming; Chen, Xing-Qiu

doi:10.1103/physrevb.106.155144

Cited by 20 publications

(2 citation statements)

References 68 publications

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“…When they form the Janus structure by replacing the A atom with a different same group atom, σ h is broken, leading to inversion symmetry breaking with the C 3 v symmetric point group. , Figure (a) shows the fully optimized crystal structure of WSiGeZ 4 . Theoretically, several intermediate structures are obtained by varying the stacking of the intermediate layer of 1H-WZ 2 and two A-Z layers. ,,− As shown in Figure (b), we have considered the four structures (H-AA, H-AB, H-BA, and H-BB) depending upon the stacking order of the three constituent (Z-Si, Z-W-Z, and Ge-Z) monolayers. As shown in Table , the lattice parameters of H-AA, H-AB, H-BA, and H-BB are only slightly different.…”

Section: Resultsmentioning

confidence: 99%

Manipulation of Valley and Spin Properties in Two-Dimensional Janus WSiGeZ₄ (Z = N, P, As) through Symmetry Control

Sheoran,

Phutela,

Moulik

et al. 2023

J. Phys. Chem. C

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A class of septuple-atomic-layer two-dimensional (2D) materials, MA2Z4, is sought as an alternative to 2D hexagonal transition metal dichalcogenides in the fields of valleytronics and spintronics. In these materials, the structural symmetry can be varied by changing the stacking of its three parts in the monolayer. We use first-principles calculations to show that in the Janus monolayer WSiGeZ4 (Z = N, P, As), Berry curvature and the Rashba effect are enhanced by modifying the stacking orders. The intrinsic electric field and composition of the d orbitals play a dominant role in determining these properties. Berry curvature is strengthened by up to 300% compared to its ground state through symmetry control, along with a significant increment in the Rashba coefficient. Moreover, monolayers WSiGeP4 and WSiGeAs4 have multiple valleys, implying another valley-dimension. The interesting spin-valley physics tunability in septuple-atomic-layer 2D materials suggests their exceptional potential for spintronic and valleytronic applications.

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Section: Resultsmentioning

confidence: 99%

Manipulation of Valley and Spin Properties in Two-Dimensional Janus WSiGeZ₄ (Z = N, P, As) through Symmetry Control

Sheoran,

Phutela,

Moulik

et al. 2023

J. Phys. Chem. C

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“…Several systems with obstructed higher-order phases have been proposed recently. Particular examples are graphdyine [7,8], graphyne [9], phosphorene [10], Xenes [11], transition metal dichalcogenides [12][13][14] and also other families of materials, such as those described in [15][16][17][18]. Along this line, in what follows, we report on the realization of an OAI phase in pentagonal palladium diselenide (PdSe 2 ) in its monolayer form.…”

Section: Introductionmentioning

confidence: 86%

Higher-order obstructed atomic insulator phase in pentagonal monolayer PdSe₂

Nuñez,

Bravo,

Correa

et al. 2023

2D Mater.

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We investigate a pentagonal monolayer of palladium diselenide, a stable two-dimensional system, as a material realization of a crystalline phase with nontrivial topological electronic properties. We find that its electronic structure involves an atomic obstructed insulator related to higher-order topology, which is a consequence of the selenium-selenium bond dimerization along with inversion and time-reversal symmetry). By means of first-principles calculations and the analysis of symmetry indicators and topological invariants, we also characterize the electronic corner states associated with the atomic obstruction and compute the corresponding corner charge for a finite geometry, which is found to be not quantized but still inversion-protected. Applying tensile strain to the finite geometry we verify the robustness of the corner states and also achieve a strain-controlled variation of the corner charge magnitude.

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Magnetic Second‐Order Topological Insulator: An Experimentally Feasible 2D CrSiTe₃

Wang

et al. 2023

Adv Funct Materials

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Abstract2D second‐order topological insulators (SOTIs) have sparked significant interest, but currently, the proposed realistic 2D materials for SOTIs are limited to nonmagnetic systems. In this study, for the first time, a single layer of chalcogenide CrSiTe3—an experimentally realized transition metal trichalcogenide is proposed with a layer structure—as a 2D ferromagnetic (FM) SOTI. Based on first‐principles calculations, this study confirms that the CrSiTe3 monolayer exhibits a nontrivial gapped bulk state in the spin‐up channel and a trivial gapped bulk state in the spin‐down channel. Based on the higher‐order bulk–boundary correspondence, it demonstrates that the CrSiTe3 monolayer exhibits topologically protected corner states with a quantized fractional charge () in the spin‐up channel. Notably, unlike previous nonmagnetic examples, the topological corner states of the CrSiTe3 monolayer are spin‐polarized and pinned at the corners of the sample in real space. Furthermore, the CrSiTe3 monolayer retains SOTI features when the spin–orbit coupling (SOC) is considered, as evidenced by the corner charge and corner states distribution. Finally, by applying biaxial strain and hole doping, this study transforms the magnetic insulating bulk states into spin‐gapless semiconducting and half‐metallic bulk states, respectively. Importantly, the topological corner states persist in the spin‐up channel under these conditions.

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Two-dimensional obstructed atomic insulators with fractional corner charge in the MA2Z4 family

Cited by 20 publications

References 68 publications

Manipulation of Valley and Spin Properties in Two-Dimensional Janus WSiGeZ₄ (Z = N, P, As) through Symmetry Control

Manipulation of Valley and Spin Properties in Two-Dimensional Janus WSiGeZ₄ (Z = N, P, As) through Symmetry Control

Higher-order obstructed atomic insulator phase in pentagonal monolayer PdSe₂

Magnetic Second‐Order Topological Insulator: An Experimentally Feasible 2D CrSiTe₃

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Two-dimensional obstructed atomic insulators with fractional corner charge in the MA2Z4 family

Cited by 20 publications

References 68 publications

Manipulation of Valley and Spin Properties in Two-Dimensional Janus WSiGeZ4 (Z = N, P, As) through Symmetry Control

Manipulation of Valley and Spin Properties in Two-Dimensional Janus WSiGeZ4 (Z = N, P, As) through Symmetry Control

Higher-order obstructed atomic insulator phase in pentagonal monolayer PdSe2

Magnetic Second‐Order Topological Insulator: An Experimentally Feasible 2D CrSiTe3

Contact Info

Product

Resources

About

Manipulation of Valley and Spin Properties in Two-Dimensional Janus WSiGeZ₄ (Z = N, P, As) through Symmetry Control

Manipulation of Valley and Spin Properties in Two-Dimensional Janus WSiGeZ₄ (Z = N, P, As) through Symmetry Control

Higher-order obstructed atomic insulator phase in pentagonal monolayer PdSe₂

Magnetic Second‐Order Topological Insulator: An Experimentally Feasible 2D CrSiTe₃