Polarization-driven band topology evolution in twisted MoTe2 and WSe2

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

Published: May 18, 2024

Abstract Motivated by recent experimental observations of opposite Chern numbers in R-type twisted MoTe 2 and WSe homobilayers, we perform large-scale density-functional-theory calculations with machine learning force fields to investigate moiré band topology across a range twist angles both materials. We find that the frontier bands change sign as function angle, this is driven competition between ferroelectricity piezoelectricity. Our calculations, enabled methods, reveal crucial insights into interactions different scales bilayer systems. The interplay atomic-level relaxation effects moiré-scale electrostatic potential variation opens new avenues for design intertwined topological correlated states, including possibility mimicking higher Landau level physics absence magnetic field.

Language: Английский

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Multiple Chern Bands in Twisted MoTe2 and Possible Non-Abelian States

Physical Review Letters, Journal Year: 2025, Volume and Issue: 134(6)

Published: Feb. 10, 2025

We investigate the moir\'e band structures and a possible even-denominator fractional quantum Hall state in small angle twisted bilayer ${\mathrm{MoTe}}_{2}$, using combined large-scale local basis density functional theory calculation continuum model exact diagonalization. Via first-principles calculations at $\ensuremath{\theta}=1.89\ifmmode^\circ\else\textdegree\fi{}$, we find sequence of $C=1$ (Chern number K valley) Chern bands analogy to Landau levels. By constructing with multiple bands, undertake band-projected diagonalization an unscreened Coulomb repulsion identify non-Abelian states near twist $\ensuremath{\theta}=1.89\ifmmode^\circ\else\textdegree\fi{}$ half filling second band.

Language: Английский

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Interplay between topology and correlations in the second moiré band of twisted bilayer MoTe2

Nature Physics, Journal Year: 2025, Volume and Issue: unknown

Published: March 20, 2025

Language: Английский

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Higher Landau-Level Analogs and Signatures of Non-Abelian States in Twisted Bilayer MoTe2

Physical Review Letters, Journal Year: 2025, Volume and Issue: 134(7)

Published: Feb. 20, 2025

Recent experimental discovery of fractional Chern insulators at zero magnetic field in moiré superlattices has sparked intense interests bringing Landau level physics to flat bands. In twisted MoTe_{2} bilayers (tMoTe_{2}), recent theoretical and studies have found three consecutive bands twist angle ∼2°. this Letter, we investigate whether higher can be these At angles 2.00° 1.89°, identify four C=1 for the K valley tMoTe_{2}. By constructing Wannier functions directly from density functional theory (DFT) calculations, a six-orbital model is developed describe bands, with orbitals forming honeycomb lattice. Exact diagonalization on top Hartree-Fock calculations are carried out functions. Especially, when second miniband half-filled, signatures non-Abelian states found. Our Wannier-based approach modeling faithful DFT wave serve as benchmarks continuum models. The possibility realizing anyons also opens up new pathway fault-tolerant quantum information processing.

Language: Английский

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Robust non-Abelian even-denominator fractional Chern insulator in twisted bilayer MoTe2

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

Published: March 3, 2025

A recent experiment has observed a series of quantum-spin-Hall effects in moiré MoTe2. Among them, the vanishing Hall signal at filling factor ν = 3 implies possible realization time-reversal pair even-denominator fractional Chern insulators. Inspired by this discovery, we numerically investigate whether robust incompressible quantum-Hall liquid can be stabilized half-filled band twisted MoTe2 bilayers. We use continuum model with parameters relevant to bilayers and obtain three consecutive nearly flat bands same number. Crucially, when second miniband is half-filled, signatures non-Abelian state are found via exact diagonalization calculations, including stable six-fold ground-state degeneracy that grows more lattice size consistent an insulator state. Our results potential realizing zero magnetic field bilayer hole 3/2. Recent experiments suggest possibility insulators transition metal dichalcogenides. Here, authors present numerics revealing magnetic-field may realized specific parameter range.

Language: Английский

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Ferromagnetism and topology of the higher flat band in a fractional Chern insulator

Nature Physics, Journal Year: 2025, Volume and Issue: unknown

Published: March 20, 2025

Language: Английский

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Non-Abelian fractional quantum anomalous Hall states and first Landau level physics of the second moiré band of twisted bilayer MoTe2

Physical review. B./Physical review. B, Journal Year: 2024, Volume and Issue: 110(16)

Published: Oct. 17, 2024

The authors report here the discovery of a realistic platform for emerging non-Abelian fractional quantum anomalous Hall states. This is second moir\'e band in 2-degree twisted bilayer MoTe${}_{2}$. They elucidate theoretical foundation behind this by demonstrating resemblance to first Landau level, using Haldane pseudopotentials and Fubini-Study metric. A surprising similarity revealed between sequence bands MoTe${}_{2}$ levels beyond particular band.

Language: Английский

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Twist-Angle-Dependent Valley Polarization of Intralayer Moiré Excitons in van der Waals Superlattices

Physical Review Letters, Journal Year: 2025, Volume and Issue: 134(2)

Published: Jan. 17, 2025

Twistronics, which utilizes the moiré potential to induce exotic excitations in twisted material systems, has garnered significant attention recent years. In this Letter, using Bethe-Salpeter calculations based on a continuum model of electronic structures, we explore optical characteristics intralayer excitons bilayer transition metal dichalcogenide heterostructures. We find Coulomb exchange interactions strongly influence these and degree valley polarization that splitting between spin-singlet spin-triplet can be effectively controlled by varying twist angle. Specifically, bright confined WSe_{2}/WS_{2} heterostructure achieve levels as high 90% at small angles, holds promise for future applications valleytronics. These findings underscore angle novel parameter manipulating properties excitons, thereby establishing semiconductors promising platform investigating many-body physics solid-state systems.

Language: Английский

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Variational mapping of Chern bands to Landau levels: Application to fractional Chern insulators in twisted MoTe2

Physical review. B./Physical review. B, Journal Year: 2025, Volume and Issue: 111(12)

Published: March 10, 2025

Language: Английский

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Non-Abelian spin Hall insulator

Physical Review Research, Journal Year: 2025, Volume and Issue: 7(2)

Published: April 24, 2025

Motivated by a recent experiment reporting the fractional quantum spin Hall effect in twisted MoTe2, we investigate microscopically prospects of realizing exotic topologically ordered states beyond conventional physics. We show that insulator, state two copies non-Abelian Moore-Read state, can be stabilized at half filling time-reversal conjugate Chern bands. elucidate existence this phase relies on reduction opposite-spin interactions short distances to overcome Ising ferromagnetism. Moreover, demonstrate band mixing provides generic mechanism for achieved. Quite remarkably, find renormalization as small 15% moiré period is sufficient transition completely spin-unpolarized which supports insulator. Furthermore, insulator either break symmetry or preserve it depending underlying topological order. Published American Physical Society 2025

Language: Английский

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