Search NASA⌕ Search
Home/Archive/DOE OSTI

DOE OSTI · 2575383

Tunable atomically enhanced moiré Berry curvatures in twisted triple bilayer graphene

Davydov, Konstantin [Univ. of Minnesota, Minneapolis, MN (United States)] (ORCID:0009000827944411)·Zhu, Ziyan [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)] (ORCID:0000000344635828)·Friedman, Noah [Univ. of Minnesota, Minneapolis, MN (United States)] (ORCID:0009000684360012)·Gramowski, Ethan [Univ. of Minnesota, Minneapolis, MN (United States)]·Li, Yaotian [Univ. of Minnesota, Minneapolis, MN (United States)]·Tavakley, Jack [Univ. of Minnesota, Minneapolis, MN (United States)]·Watanabe, Kenji [National Institute for Materials Science (NIMS), Tsukuba (Japan)] (ORCID:0000000337018119)·Taniguchi, Takashi [National Institute for Materials Science (NIMS), Tsukuba (Japan)] (ORCID:0000000214673105)·Luskin, Mitchell [Univ. of Minnesota, Minneapolis, MN (United States)] (ORCID:000000031981199X)·Kaxiras, Efthimios [Harvard Univ., Cambridge, MA (United States)] (ORCID:0000000246820165)·Wang, Ke [Univ. of Minnesota, Minneapolis, MN (United States)] (ORCID:0000000208954445)
View original source ↗Read source document ↗Export metadata ↓

Abstract

We report a twisted triple bilayer graphene platform consisting of three units of Bernal bilayer graphene consecutively twisted at 1.49° and 1.68°. We demonstrate the atomic reconstruction between the two competing moiré superlattices strongly enhances the Berry curvature of each moiré band insulator state, characterized by measured strong nonlocal valley Hall effect that sensitively depends on the intermoiré competition strength, tunable by manipulating the out-of-plane carrier distribution. Our study sheds light on the microscopic mechanism of atomic and electronic reconstruction in twisted multilayer systems, by systematically investigating transport signatures of moiré Berry curvature and its enhancement from moiré-of-moiré lattice reconstruction. In conclusion, we show that the reconstructed electronic band can be versatilely tuned by electrostatics, providing an approach toward engineering the band structure and its topology for a quantum material platform with designer electrical and optical properties.

Explore related subjects

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITYGrapheneQuantum transportTwistronicsValleytronicsVan der Waals systems

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Davydov, Konstantin [Univ. of Minnesota, Minneapolis, MN (United States)] (ORCID:0009000827944411), Zhu, Ziyan [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)] (ORCID:0000000344635828), Friedman, Noah [Univ. of Minnesota, Minneapolis, MN (United States)] (ORCID:0009000684360012), Gramowski, Ethan [Univ. of Minnesota, Minneapolis, MN (United States)], Li, Yaotian [Univ. of Minnesota, Minneapolis, MN (United States)], Tavakley, Jack [Univ. of Minnesota, Minneapolis, MN (United States)], Watanabe, Kenji [National Institute for Materials Science (NIMS), Tsukuba (Japan)] (ORCID:0000000337018119), Taniguchi, Takashi [National Institute for Materials Science (NIMS), Tsukuba (Japan)] (ORCID:0000000214673105), Luskin, Mitchell [Univ. of Minnesota, Minneapolis, MN (United States)] (ORCID:000000031981199X), Kaxiras, Efthimios [Harvard Univ., Cambridge, MA (United States)] (ORCID:0000000246820165), Wang, Ke [Univ. of Minnesota, Minneapolis, MN (United States)] (ORCID:0000000208954445). 2025-04-23. Tunable atomically enhanced moiré Berry curvatures in twisted triple bilayer graphene. https://doi.org/10.1103/physrevb.111.l161120

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related reports

DOE OSTI2026

STM/S Grid LDOS Data and Analysis Code for Deciphering Majorana Zero Modes in Topological Superconductor

This dataset provides raw millikelvin scanning tunneling microscopy/spectroscopy (STM/S) grid spectroscopy data and Python analysis scripts supporting the manuscript “Deciphering Majorana Zero Modes in Topological Superconductor FeTe0.55Se0.45 with Machine-Learning-Assisted Spectral Deconvolution.” The dataset includes a raw grid spectroscopy file acquired on FeTe0.55Se0.45 at 40 mK under magnetic field, together with Python/Jupytext analysis scripts used for STM/S data processing, visualization, spectral deconvolution, Lorentzian peak fitting, feature extraction, machine-learning-assisted clustering, and figure generation. These files support the analysis of vortex-core local density of states and the identification of zero-bias-peak-related spectral components from complex in-gap states. The dataset is intended to provide a citable archival record of the data and analysis code associated with the published manuscript and to support transparency and reproducibility of the reported STM/S and machine-learning workflow.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2026

Dielectric Resonator Design for Low Power and Low Temperature Microwave Plasma

Waveguide-based microwave plasmas generally operate at high temperatures (2000 - 6000K)[1], making it difficult to directly interface solid materials with the plasma without significant thermal damage. Dielectric microwave resonators (DMRs), long studied for wave-based manipulation of electromagnetic radiation for telecom and optics, can focus radiation to extremely small mode volumes, creating intense localized fields with low-power input.[2] This phenomenon can be used for applications ranging from efficient plasma electronics to near-ambient plasma-materials interactions. Such DMR-based plasmas have been demonstrated a handful of times in the literature, but the majority of research towards this utilize the lowest frequency resonance mode.[3], [4], [5] By carefully controlling the geometry of cylindrical resonators, a variety of electromagnetic modes can be excited. In this work, COMSOL Multiphysics simulations are used to study the electric field enhancement and absorption properties of CaTiO3 DMRs as a function of geometry and excitation frequency. Whereas previous studies have utilized the HEM111 resonance frequency to drive low power plasma excitation, we find that higher order resonance frequencies are more effective at field enhancement and result in less power loss within the dielectric material, hence less wasted heating. The effectiveness of these modes is also geometry dependent and can be computationally optimized for plasma generation. Complementing these computational efforts, we demonstrate a new closed-system reactor design built in a WR-650 waveguide and experimentally demonstrate the formation of atmospheric argon microwave plasma using < 30 W input power on DMR dimers. We observe a shifting resonance frequency as the DMRs heat in response to microwave excitation and develop a Python-based lock-in mechanism to effectively track the DMR resonance over time, leading to stable plasma operation. We use infrared thermal imaging to monitor the temperature of the DMR dimers and surrounding quartz chamber, demonstrating thermal temperatures < 60 degreesC. Finally, we utilize optical emission spectroscopy (OES) to probe the plasma properties as a function of the resonance mode.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗