Efficient Prediction of Superlattice and Anomalous Miniband Topology from Quantum Geometry

Physical Review X, Journal Year: 2025, Volume and Issue: 15(1)

Published: Jan. 13, 2025

Two-dimensional materials subject to long-wavelength modulations have emerged as novel platforms study topological and correlated quantum phases. In this article, we develop a versatile computationally inexpensive method predict the properties of subjected superlattice potential by combining degenerate perturbation theory with symmetry indicators. absence electronic interactions, our analysis provides systematic rule find Chern number superlattice-induced miniband starting from harmonics applied few material-specific coefficients. Our also applies anomalous (interaction-generated) bands, for which derive an efficient algorithm determine all numbers compatible self-consistent solution Hartree-Fock equations. approach gives microscopic understanding Hall insulators recently observed in rhombohedral graphene multilayers. Published American Physical Society 2025

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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Chern Insulators at Integer and Fractional Filling in Moiré Pentalayer Graphene

Physical Review X, Journal Year: 2025, Volume and Issue: 15(1)

Published: Feb. 27, 2025

The advent of moiré platforms for engineered quantum matter has led to discoveries integer and fractional anomalous Hall effects, with predictions correlation-driven topological states based on electron crystallization. Here, we report an array trivial insulators formed in a lattice rhomobohedral pentalayer graphene (R5G). At doping one per unit cell (ν=1), see correlated insulator Chern number that can be tuned between C=0 +1 by electric displacement field. This is accompanied series additional C=+1 originating from fillings the lattice—ν=1/4, 1/3, 2/3—associated formation moiré-driven electronic crystals. ν=2/3 system exhibits effect at zero magnetic field, but further develops hints incipient C=2/3 modest Our results establish R5G as fertile platform studying competition potential intertwining insulators. Published American Physical Society 2025

Language: Английский

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Electric Field Control Of Moiré Skyrmion Phases in Twisted Multiferroic NiI₂ Bilayers

Nano Letters, Journal Year: 2024, Volume and Issue: unknown

Published: Nov. 22, 2024

Twisted magnetic van der Waals materials provide a flexible platform to engineer unconventional magnetism. Here we demonstrate the emergence of electrically tunable topological moiré magnetism in twisted bilayers spin-spiral multiferroic NiI2. We establish rich phase diagram featuring uniform spiral phases, variety kπ-skyrmion lattices, and nematic spin textures ordered at scale. The these phases is driven by local stacking resulting modulated frustration. Notably, when wavelength commensurate with length scale an integer k, multiwalled skyrmions become pinned pattern. show that strong magnetoelectric coupling displayed allows electric control lattices out-of-plane field. Our results highly for skyrmionics based on multiferroics, potentially enabling new generation ultrathin topologically protected spintronic devices.

Language: Английский

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Two-dimensional homogeneous electron gas with symmetric dual-gate screening: Exchange-correlation functional and other ground-state properties

Physical review. B./Physical review. B, Journal Year: 2025, Volume and Issue: 111(4)

Published: Jan. 16, 2025

Language: Английский

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Time-resolved ARPES and optical transport properties of irradiated twisted bilayer graphene in a steady state

Physical review. B./Physical review. B, Journal Year: 2025, Volume and Issue: 111(3)

Published: Jan. 21, 2025

Language: Английский

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Exploring Structure Diversity in Atomic Resolution Microscopy With Graph

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

Published: Feb. 23, 2025

The emergence of deep learning (DL) has provided great opportunities for the high-throughput analysis atomic-resolution micrographs. However, DL models trained by image patches in fixed size generally lack efficiency and flexibility when processing micrographs containing diversified atomic configurations. Herein, inspired similarity between structures graphs, a few-shot framework based on an equivariant graph neural network (EGNN) to analyze library (e.g., vacancies, phases, grain boundaries, doping, etc.) is described, showing significantly promoted robustness three orders magnitude reduced computing parameters compared image-driven models, which especially evident those aggregated vacancy lines with flexible lattice distortion. Besides, intuitiveness graphs enables quantitative straightforward extraction atomic-scale structural features batches, thus statistically unveiling self-assembly dynamics under electron beam irradiation. A versatile model toolkit established integrating EGNN sub-models single structure recognition process images involving varied configurations form task chain, leading discovery novel doping superior electrocatalytic properties hydrogen evolution reactions. This work provides powerful tool explore diversity fast, accurate, intelligent manner.

Language: Английский

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Scanning tunneling microscopy study of twisted Bernal-stacked tetralayer graphene

Physical review. B./Physical review. B, Journal Year: 2025, Volume and Issue: 111(11)

Published: March 11, 2025

Language: Английский

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Coexistence of ergodic and nonergodic behavior and level spacing statistics in a one-dimensional model of a flat band superconductor

Physical Review Research, Journal Year: 2025, Volume and Issue: 7(1)

Published: March 26, 2025

Motivated by recent studies of the projected dice lattice Hamiltonian [K. Swaminathan , ], we introduce on-site/bond singlet (OBS) model, a one-dimensional model flat band superconductor, in order to better understand quasiparticle localization and interesting coexistence ergodic nonergodic behavior present former model. The OBS is sum terms that have direct counterparts Hamiltonian, each which parameterized coupling constant. Exact diagonalization reveals energy spectrum nonequilibrium dynamics are essentially same as for some values constants. breaking ergodicity manifest striking manner level spacing distribution. Its near Poissonian form provides evidence existence local integrals motion establishes nontrivial integrable generalization Creutz ladder Hamiltonian. These results show statistics promising tool study excitations superconductors. Published American Physical Society 2025

Language: Английский

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Machine Learning Exploration of Topological Polarization Pattern in Hexagonal Boron Nitride Moiré Superlattice

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

Published: April 13, 2025

Abstract Twisted moiré supercells, which can be approximated as a combination of sliding bilayers and constitute various topologically nontrivial polarization patterns, attract extensive attention recently. However, because the excessive size supercell, most studies are based on effective models lack results first‐principles calculation. In this work, machine learning to determine topological structure pattern is used in twisted strained hexagonal boron nitride ( h ‐BN). This study further confirms that effectively modulated by vertical electric field lattice mismatch. Finally, local also exists antiparallel stacked ‐BN bilayers. work provides detailed superlattice, believe facilitate more research ferroelectricity, physics, related fields.

Language: Английский

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