The copresence of multiple Dirac bands in few-layer graphene leads to a rich phase diagram in the quantum Hall regime. Using transport measurements, we map the phase diagram of BN-encapsulated ABA-stacked trilayer graphene as a function charge density n, magnetic field B, and interlayer displacement field D, and observe transitions among states with different spin, valley, orbital, and parity polarizations. Such a rich pattern arises from crossings between Landau levels from different subbands, which reflect the evolving symmetries that are tunable in situ. At D=0, we observe fractional quantum Hall (FQH) states at filling factors 2/3 and -11/3. Unlike those in bilayer graphene, these FQH states are destabilized by a small interlayer potential that hybridizes the different Dirac bands.
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http://dx.doi.org/10.1103/PhysRevLett.117.076807 | DOI Listing |
Annu Rev Phys Chem
January 2025
1Department of Chemistry, University of Illinois Chicago, Chicago, Illinois, USA; email:
Inspired by the success of graphene, two-dimensional (2D) materials have been at the forefront of advanced (opto-)nanoelectronics and energy-related fields owing to their exotic properties like sizable bandgaps, Dirac fermions, quantum spin Hall states, topological edge states, and ballistic charge carrier transport, which hold promise for various electronic device applications. Emerging main group elemental 2D materials, beyond graphene, are of particular interest due to their unique structural characteristics, ease of synthetic exploration, and superior property tunability. In this review, we present recent advances in atomic-scale studies of elemental 2D materials with an emphasis on synthetic strategies and structural properties.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Department of Chemistry, Queen's University, Chernoff Hall, Kingston, Ontario K7L 3N6, Canada.
The use of gold nanoclusters in biomedical applications has been steadily increasing in recent years. However, water solubility is a key factor for these applications, and water-soluble gold nanoclusters are often difficult to isolate and susceptible to exchange or oxidation in vivo. Herein, we report the isolation of N-heterocyclic carbene (NHC)-protected atomically precise gold nanoclusters functionalized with triethylene glycol monomethyl ether groups.
View Article and Find Full Text PDFNano Lett
January 2025
Max Planck Institute for Solid State Research, Heisenbergstr. 1, Stuttgart, 70569, Germany.
Spin Hall nano-oscillators convert DC to magnetic auto-oscillations in the microwave regime. Current research on these devices is dedicated to creating next-generation energy-efficient hardware for communication technologies. Despite intensive research on magnetic auto-oscillations within the past decade, the nanoscale mapping of those dynamics remained a challenge.
View Article and Find Full Text PDFiScience
January 2025
School of Physics and Electronics, Shandong Normal University, Jinan 250358, China.
The quantum anomalous Hall effect (QAHE) demonstrates the potential for achieving quantized Hall resistance without the need for an external magnetic field, making it highly promising for reducing energy loss in electronic devices. Its realization and research rely heavily on precise first-principles calculations, which are essential for analyzing the electronic structures and topological properties of novel two-dimensional (2D) materials. This review article explores the theoretical progress of QAHE in 2D hexagonal monolayers with strong spin-orbit coupling and internal magnetic ordering.
View Article and Find Full Text PDFAdv Mater
January 2025
Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea.
Magnetization switching by charge current without a magnetic field is essential for device applications and information technology. It generally requires a current-induced out-of-plane spin polarization beyond the capability of conventional ferromagnet/heavy-metal systems, where the current-induced spin polarization aligns in-plane orthogonal to the in-plane charge current and out-of-plane spin current. Here, a new approach is demonstrated for magnetic-field-free switching by fabricating a van-der-Waals magnet and oxide FeGeTe/SrTiO heterostructure.
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