The electronic structure of a crystalline solid is largely determined by its lattice structure. Recent advances in van der Waals solids, artificial crystals with controlled stacking of two-dimensional (2D) atomic films, have enabled the creation of materials with novel electronic structures. In particular, stacking graphene on hexagonal boron nitride (hBN) introduces a moiré superlattice that fundamentally modifies graphene's band structure and gives rise to secondary Dirac points (SDPs). Here we find that the formation of a moiré superlattice in graphene on hBN yields new, unexpected consequences: a set of tertiary Dirac points (TDPs) emerge, which give rise to additional sets of Landau levels when the sample is subjected to an external magnetic field. Our observations hint at the formation of a hidden Kekulé superstructure on top of the moiré superlattice under appropriate carrier doping and magnetic fields.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1021/acs.nanolett.7b00735 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Nanoscopic Supercapacitance Elucidations of the Graphene-Ionic Interface with Suspended/Supported Graphene in Different Ionic Solutions.
ACS Appl Mater Interfaces
January 2025
Graduate Institute of Electronics Engineering, National Taiwan University, Taipei 10617, Taiwan.
Graphene-based supercapacitors have gained significant attention due to their exceptional energy storage capabilities. Despite numerous research efforts trying to improve the performance, the challenge of experimentally elucidating the nanoscale-interface molecular characteristics still needs to be tackled for device optimizations in commercial applications. To address this, we have conducted a series of experiments using substrate-free graphene field-effect transistors (SF-GFETs) and oxide-supported graphene field-effect transistors (OS-GFETs) to elucidate the graphene-electrolyte interfacial arrangement and corresponding capacitance under different surface potential states and ionic concentration environments.
View Article and Find Full Text PDFPhase transitions, Dirac and Weyl semimetal states in MnGeBiTe.
Sci Rep
January 2025
Saint Petersburg State University, St. Petersburg, 198504, Russia.
Using angle-resolved photoemission spectroscopy (ARPES) and density functional theory (DFT), an experimental and theoretical study of changes in the electronic structure (dispersion dependencies) and corresponding modification of the energy band gap at the Dirac point (DP) for topological insulator (TI) [Formula: see text] have been carried out with gradual replacement of magnetic Mn atoms by non-magnetic Ge atoms when concentration of the latter was varied from 10% to 75%. It was shown that when Ge concentration increases, the bulk band gap decreases and reaches zero plateau in the concentration range of 45-60% while trivial surface states (TrSS) are present and exhibit an energy splitting of 100 and 70 meV in different types of measurements. It was also shown that TSS disappear from the measured band dispersions at a Ge concentration of about 40%.
View Article and Find Full Text PDFConstructing the Dirac Electronic Behavior Database of Under-Stress Transition Metal Dichalcogenides for Broad Applications.
Adv Mater
January 2025
CAS Center for Excellence in Nanoscience, Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing, 100083, China.
Article Synopsis
- Discovering the optoelectronic properties of transition metal dichalcogenides (TMDCs) is crucial for next-gen electronic devices, with a focus on the impact of external strains on Dirac states, an area still being explored.
- A comprehensive database of 90 TMDC types was created, revealing that 27.3% exhibit Dirac materials with three distinct types of Dirac cones, influenced by external strain-induced electron localization.
- The study shows that TMDCs from tellurides with 1H phase enhance the formation of Dirac cones under stress, leading to metallic properties and increased charge transport, ultimately offering insights for the development of TMDCs in superconducting and optoelectronic applications.
Entanglement microscopy and tomography in many-body systems.
Nat Commun
January 2025
Department of Physics and HK Institute of Quantum Science & Technology, The University of Hong Kong, Hong Kong, Hong Kong.
Quantum entanglement uncovers the essential principles of quantum matter, yet determining its structure in realistic many-body systems poses significant challenges. Here, we employ a protocol, dubbed entanglement microscopy, to reveal the multipartite entanglement encoded in the full reduced density matrix of the microscopic subregion in spin and fermionic many-body systems. We exemplify our method by studying the phase diagram near quantum critical points (QCP) in 2 spatial dimensions: the transverse field Ising model and a Gross-Neveu-Yukawa transition of Dirac fermions.
View Article and Find Full Text PDFNon-Abelian lattice gauge fields in photonic synthetic frequency dimensions.
Nature
January 2025
Edward L. Ginzton Laboratory, Stanford University, Stanford, CA, USA.
Article Synopsis
- Non-Abelian gauge fields play a crucial role in explaining spin-related phenomena across various fields of physics, and lattice models help in exploring their applications.
- Researchers successfully demonstrated SU(2) lattice gauge fields for photons in synthetic frequency dimensions, marking a significant advancement since this had not been previously achieved.
- The study reveals the properties of these lattice gauge fields, such as Dirac cones and their implications for topological physics, which could enhance photonic technologies by controlling photon spins in innovative ways.
Want AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!