Nb3Cl8: a prototypical layered Mott-Hubbard insulator

npj Quantum Materials, Journal Year: 2024, Volume and Issue: 9(1)

Published: Jan. 12, 2024

Abstract Despite its simplicity and relevance for the description of electronic correlations in solids, Hubbard model is seldom inarguably realized real materials. Here, we show that monolayer Nb 3 Cl 8 an ideal candidate to be described within a single-orbital model, constructed “molecular” rather than atomic basis set using ab initio constrained random phase approximation calculations. We provide necessary ingredients connect experimental reality with material descriptions correlated electron theory, which clarifies Mott insulator gap about 1.4 2.0 eV depending on dielectric environment. Comparisons atomistic three-orbital single-molecular-orbital adequate reliable. further comment magnetic structure compound insulating state survives low-temperature bulk phases featuring distinct experimentally verifiable characteristics.

Language: Английский

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Cataloging High‐Quality Two‐Dimensional van der Waals Materials with Flat Bands

Advanced Functional Materials, Journal Year: 2024, Volume and Issue: 34(19)

Published: Jan. 8, 2024

Abstract Benefited from the lower dimensionality compared to their 3D counterpart, 2D flat‐band systems provide cleaner lattice models, easier experimental verification, and higher tunability, which make van der Waals (vdW) system an ideal playground for exploring physics as well potential applications. Given vast amount of research in field flat bands, a simple efficient approach search realistic vdW materials with bands is still missing. Here, two‐tier framework filter diagnose high‐quality by combining high‐throughput first‐principles calculations proposed score criterion presented. Based on systematic geometrical analysis, 861 monolayer are initially obtained amounting 187,093 structures stored Inorganic Crystal Structure Database. By applying criterion, 229 candidates efficiently identified, among sub‐catalog 74 right next Fermi level further provided facilitate verification. All these efforts screen experimentally available will certainly motivate continuing exploration toward realization this class special applications material science.

Language: Английский

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2D Kagome Materials: Theoretical Insights, Experimental Realizations, and Electronic Structures

Advanced Functional Materials, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 14, 2025

Abstract In recent years, kagome materials have attracted significant attention due to their rich emergent phenomena arising from the quantum interplay of geometry, topology, spin, and correlations. However, in search for materials, it has been found that bulk compounds with electronic properties related lattice are relatively scarce, primarily hybridization layers adjacent layers. Therefore, researchers shown increasing interest discovery construction 2D aiming achieve clean bands near Fermi level monolayer or few‐layer systems. Substantial advancements already made this area. review, current progress is summarized development materials. The geometric structures model begin by introducing its variants, followed discussions on experimental realizations structure characterizations Finally, an outlook provided future developments

Language: Английский

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Artificial kagome lattices of Shockley surface states patterned by halogen hydrogen-bonded organic frameworks

Nature Communications, Journal Year: 2024, Volume and Issue: 15(1)

Published: April 6, 2024

Abstract Artificial electronic kagome lattices may emerge from potential landscapes using customized structures with exotic supersymmetries, benefiting the confinement of Shockley surface-state electrons on coinage metals, which offers a flexible approach to realizing intriguing quantum phases matter that are highly desired but scarce in available materials. Here, we devise general strategy construct varieties by utilizing on-surface synthesis halogen hydrogen-bonded organic frameworks (XHOFs). As proof concept, demonstrate three XHOFs Ag(111) and Au(111) surfaces, correspondingly deliver regular, breathing, chiral breathing diatomic-kagome patterned landscapes, showing evident topological edge states at interfaces. The combination scanning tunnelling microscopy noncontact atomic force microscopy, complemented density functional theory tight-binding calculations, directly substantiates our method as reliable effective way achieve for engineering states.

Language: Английский

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Atomically Thin Kagome-Structured Co₉Te₁₆ Achieved through Self-Intercalation and Its Flat Band Visualization

Nano Letters, Journal Year: 2024, Volume and Issue: 24(25), P. 7672 - 7680

Published: June 13, 2024

Kagome materials have recently garnered substantial attention due to the intrinsic flat band feature and stimulated magnetic spin-related many-body physics. In contrast their bulk counterparts, two-dimensional (2D) kagome more distinct bands, beneficial for exploring novel quantum phenomena. Herein, we report direct synthesis of an ultrathin kagome-structured Co-telluride (Co

Language: Английский

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Flat‐Band Electronic Bipolarity in a Janus and Kagome van der Waals Semiconductor Nb₃TeI₇

Advanced Materials, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 13, 2025

Janus materials, a novel class of materials with two faces different chemical compositions and electronic polarities, offer significant potential for various applications catalytic reactions, sensing, optical or responses. A key aspect such functionalities is face-dependent bipolarity, which usually limited by the distinction terminated surfaces has not been exploited in semiconducting regime. Here, it showed that Kagome van der Waals (vdW) material Nb3TeI7 ferroelectric-like coherent stacking layers hosts strong bipolar states large difference ∼ 0.7 eV between I4 TeI3 observed, despite only one fourth I atoms being replaced Te on side layers. Additionally, robust properties n-type p-type field-effect transistor behaviors are demonstrated. These unique attributed to Nb 4d orbital flat bands breathing-Kagome lattice, significantly electron mass makes immune impurity doping, inherent correlation enhances asymmetric distribution, thereby amplifying built-in electric field. findings highlight naturally-grown vdW semiconductors provide promising platform utilizing bipolarity 2D-material-based applications.

Language: Английский

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Ferromagnetism and correlated insulating states in monolayer Mo33Te56

Nature Communications, Journal Year: 2025, Volume and Issue: 16(1)

Published: March 31, 2025

Although the kagome model is fundamentally two-dimensional, essential physics, i.e., kagome-bands-driven emergent electronic states, has yet to be explored in monolayer limit. Here, we present experimental realization of physics Mo33Te56, showcasing both ferromagnetic ordering and a correlated insulating state with an energy gap up 15 meV. Using combination scanning tunnelling microscopy theoretical calculations, find structural phase Mo-Te compound, which forms mirror-twin boundary loop superlattice exhibiting geometry multiple sets bands. The partial occupancy these nearly flat bands results Fermi surface instability, counteracted by emergence order (with coercive field ~0.1 T, as observed spin-polarized STM) opening hard gap. Our work establishes robust framework featuring well-defined atomic band structures, alongside intrinsic two-dimensional nature, for rigorous examination physics. lattice known host rich array phenomena, but thus far number examples truly two dimensional systems are limited. Pan, Xiong, Dai, Zhang, coauthors compound structure, driven states.

Language: Английский

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Superconductivity in breathing kagome-structured C14 laves phase XOs2(X = Zr,Hf)

Superconductor Science and Technology, Journal Year: 2024, Volume and Issue: 37(7), P. 075004 - 075004

Published: May 12, 2024

Abstract Recently, the emergence of superconductivity in kagome metals has generated significant interest due to its interaction with flat bands and topological electronic states, which exhibit a range unusual quantum characteristics. This study thoroughly investigates largely unexplored breathing structure C14 Laves phase compounds XOs 2 (X = Zr, Hf) by XRD, electrical transport, magnetization, specific heat measurements. Our analyses confirm presence MgZn -type ZrOs HfOs compounds, exhibiting type-II critical temperature ( T C ) values 2.90(3) K 2.69(6) K, respectively. Furthermore, measurements electron–phonon coupling constants for both indicate weakly coupled fully gapped superconductivity.

Language: Английский

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Large second-harmonic generation and linear electro-optic effect in the bulk kagome lattice compound Nb3MX7 ( M=Se…

Physical review. B./Physical review. B, Journal Year: 2024, Volume and Issue: 109(11)

Published: March 11, 2024

Layered $\mathrm{N}{\mathrm{b}}_{3}M{X}_{7}$ ($M=\mathrm{Se},\mathrm{S},\mathrm{Te}$; $X=\mathrm{I},\mathrm{Br}$) compounds with a noncentrosymmetric kagome lattice structure constitute promising candidate for exhibiting optical anisotropy and nonlinearity. Nevertheless, there has been limited research on their nonlinear properties both theoretically experimentally. In this paper, we systematically study the linear responses of bulk family. Previously, two distinct stacking sequences (i.e., AA AB stacking) in had identified experiments. Therefore, influence sequence isoelectronic substitution response are investigated. It reveals that all four materials (AB-$\mathrm{N}{\mathrm{b}}_{3}\mathrm{Te}{\mathrm{I}}_{7}$, AA-$\mathrm{N}{\mathrm{b}}_{3}\mathrm{Te}{\mathrm{I}}_{7}$, AB-$\mathrm{N}{\mathrm{b}}_{3}\mathrm{Se}{\mathrm{I}}_{7}$, AA-$\mathrm{N}{\mathrm{b}}_{3}\mathrm{SB}{\mathrm{r}}_{7}$) exhibit significant second-harmonic generation electro-optic effects. Notably, coefficient (${\ensuremath{\chi}}_{zzz}^{(2)}$) AB-$\mathrm{N}{\mathrm{b}}_{3}\mathrm{Te}{\mathrm{I}}_{7}$ reaches 3081 pm/V at 0.91 eV, which is nearly 14 times as large known material GaN. Furthermore, exhibits ${r}_{zzz}$(0) 5.94 pm/V, outperforms GaN by almost tenfold. The prominent observed attributed to intralayer directional covalent bonding. Our findings indicate would have potential applications devices.

Language: Английский

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Atomically Thin Two-Dimensional Kagome Flat Band on the Silicon Surface

ACS Nano, Journal Year: 2024, Volume and Issue: 18(37), P. 25535 - 25541

Published: Aug. 30, 2024

In condensed matter physics, the Kagome lattice and its inherent flat bands have attracted considerable attention for their prediction observation to host a variety of exotic physical phenomena. Despite extensive efforts fabricate thin films materials aimed at modulating through electrostatic gating or strain manipulation, progress has been limited. Here, we report d-orbital hybridized Kagome-derived band in Ag/Si(111) 3×3 as revealed by angle-resolved photoemission spectroscopy. Our findings indicate that silver atoms on silicon substrate form an unconventional distorted breathing structure, where delicate balance hopping parameters in-plane d-orbitals leads destructive interference, resulting double bands. The exact quantum interference mechanism forms is uncovered rigorous manner not described before. These results illuminate potential integrating metal–semiconductor interfaces semiconductor surfaces into particularly exploring ideal 2D systems.

Language: Английский

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