Article
Biochemistry & Molecular Biology
Jingran Liu, Chaobo Luo, Haolin Lu, Zhongkai Huang, Guankui Long, Xiangyang Peng
Summary: The study investigates the properties of graphene supported by hBN and forming moiré structures, revealing changes in energy gaps and Fermi velocity with twisting angles. The periodic potential imposed by hBN affects charge distributions in graphene, influencing band structures.
Article
Chemistry, Physical
Yang Ge, Lingxiu Chen, Chengxin Jiang, Jianlong Ji, Qiuyun Tan, Douxing Pan, Wendong Zhang, Riguang Zhang, Eli Janzen, James H. Edgar, Shengbo Sang, Haomin Wang
Summary: In this study, triangular zigzag-edged graphene nanoflakes (GNFs) were successfully synthesized and found to exhibit high magnetization. Density functional theory calculations revealed that this magnetic property is a result of superexchange interactions among unpaired electrons at the zigzag C-BN interface. This research provides a promising platform for experimentally achieving GNFs with high electron spin states.
Article
Nanoscience & Nanotechnology
Chengxin Jiang, Lingxiu Chen, Huishan Wang, Chen Chen, Xiujun Wang, Ziqiang Kong, Yibo Wang, Haomin Wang, Xiaoming Xie
Summary: Graphene on hexagonal boron nitride (h-BN) demonstrates excellent electrical properties, which are affected by its domain size and boundaries. Chemical vapor deposition (CVD) is a hopeful method for large graphene crystal growth, but increasing the coverage of monolayer graphene on h-BN remains a challenge due to weak control of nucleation and vertical growth. In this study, an auxiliary source strategy using silicon carbide and methyl methacrylate is adopted to enhance graphene nucleation density and achieve continuous graphene films on h-BN. By optimizing the growth temperature, vertical accumulation of graphitic materials can be suppressed. This work provides an effective approach for preparing continuous graphene film on h-BN and offers insights for the growth of high-quality graphene.
Article
Chemistry, Multidisciplinary
Ping Wang, Woncheol Lee, Joseph P. Corbett, William H. Koll, Nguyen M. Vu, David Arto Laleyan, Qiannan Wen, Yuanpeng Wu, Ayush Pandey, Jiseok Gim, Ding Wang, Diana Y. Qiu, Robert Hovden, Mackillo Kira, John T. Heron, Jay A. Gupta, Emmanouil Kioupakis, Zetian Mi
Summary: This study proposes a growth process mediated by an hBN/G interface for the controlled synthesis of high-quality monolayer hBN. The scalable epitaxy of unidirectional monolayer hBN on graphene aligned to the underlying graphene lattice is achieved. Additionally, it is discovered that monolayer hBN exhibits deep-ultraviolet emission with a giant renormalized direct bandgap on graphene.
ADVANCED MATERIALS
(2022)
Article
Chemistry, Physical
E. Magnano, S. Nappini, I Pis, T. O. Mentes, F. Genuzio, A. Locatelli, F. Bondino
Summary: In this study, the growth of h-BNG thin films on platinum and their behavior in an oxygen environment were investigated using surface science techniques. By selectively etching graphene and repeating growth cycles, controllable h-BNG layers and vertically stacked h-BN/Gr heterostructures were successfully obtained.
APPLIED SURFACE SCIENCE
(2022)
Article
Materials Science, Multidisciplinary
Gaia Forghieri, Paolo Bordone, Andrea Bertoni
Summary: Graphene nanoribbons serve as an ideal platform for electronic interferometry in the integer quantum Hall regime. By solving the time-dependent Schrodinger equation for single carriers in graphene, the study reveals the effects of carrier localization on their transport characteristics in pn junctions. Two types of Mach-Zender interferometers are simulated, showing expected and unexpected phenomena.
Article
Chemistry, Multidisciplinary
Angus Gale, Dominic Scognamiglio, Ivan Zhigulin, Benjamin Whitefield, Mehran Kianinia, Igor Aharonovich, Milos Toth
Summary: Negatively charged boron vacancies (VB-) in hexagonal boron nitride (hBN) have become of interest as spin defects for quantum information processing and quantum sensing. This study investigates the switching of charge states of VB defects in hBN under laser and electron beam excitation, demonstrating deterministic and reversible switching between the -1 and 0 states controlled by excess electrons or holes injected into hBN by a layered heterostructure device. This work provides a means to monitor and manipulate the charge state of VB defects, enabling the stabilization of the -1 state necessary for spin manipulation and optical readout.
Article
Chemistry, Physical
Nasim Anousheh, Azar Shamloo, Seifollah Jalili, Jack A. Tuszynski
Summary: Understanding the behavior of confined electrolyte solutions in graphene-based channels is important for various scientific applications. In this study, molecular dynamics simulations were used to investigate the adsorption of NaCl electrolyte solutions in graphene, hexagonal boron nitride, and combined graphene-hexagonal boron nitride nano-channels. The study reveals the advantageous adsorption of sodium and chloride ions in the graphene-hexagonal boron nitride-graphene structure.
JOURNAL OF MOLECULAR LIQUIDS
(2022)
Article
Engineering, Chemical
Pengbo Hu, Shujuan Wang, Yuqun Zhuo
Summary: In this study, the adsorption mechanisms of CO2 on pure/doped h-BN were investigated using DFT calculations, revealing that doping of C/N and presence of H2O can enhance CO2 adsorption. It was also found that the TS energy barrier of CO2 adsorption is a crucial factor affecting adsorption strength. These research results provide valuable information for exploiting h-BN for massive CO2 adsorption in industrial situations.
SEPARATION AND PURIFICATION TECHNOLOGY
(2021)
Article
Chemistry, Multidisciplinary
Alexander Mehler, Nicolas Neel, Elena Voloshina, Yuriy Dedkov, Jorg Kroger
Summary: The study demonstrates the growth of graphene on h-BN through thermal decomposition and catalytic assistance of metal substrates, as well as the epitaxial growth of h-BN on Pt(111). Different honeycomb structures of graphene on h-BN and the observation of distinct superstructures at small probe-surface distances are highlighted in this study.
Article
Chemistry, Multidisciplinary
Huibin Sun, Yunlei Jiang, Renjie Hua, Runhua Huang, Lei Shi, Yuan Dong, Suxia Liang, Jing Ni, Chi Zhang, Ruoyu Dong, Yingru Song
Summary: Graphene/BN heterostructures exhibit significant thermal rectification behavior, and the rectification ratio increases with the system length. This phenomenon is attributed to the mismatch of out-of-plane phonon vibration modes at the interface. This two-dimensional heterostructure shows promise for thermal management.
Article
Chemistry, Multidisciplinary
Adrian Hemmi, Ari Paavo Seitsonen, Thomas Greber, Huanyao Cun
Summary: The production of high-quality hexagonal boron nitride (h-BN) is crucial for 2D materials-based devices, and excluding carbon during the process is important to prevent the formation of graphene. Surface reaction-assisted conversion from h-BN to graphene can be achieved through high-temperature treatments.
Article
Chemistry, Multidisciplinary
Nermina Brljak, Ruitao Jin, Tiffany R. Walsh, Marc R. Knecht
Summary: The study identified a peptide sequence with affinity for h-BN, called BP7, and developed a new method to manipulate the surface properties of nanosheet materials through mutation studies and bio-conjugation. When conjugated with a fatty acid, BP7 was able to create highly viscoelastic interfaces, offering a new pathway for organizing and conjugating h-BN nanosheets in liquid water.
Article
Chemistry, Multidisciplinary
Eli Janzen, Hannah Schutte, Juliette Plo, Adrien Rousseau, Thierry Michel, Wilfried Desrat, Pierre Valvin, Vincent Jacques, Guillaume Cassabois, Bernard Gil, James H. Edgar
Summary: The changes in the properties of hexagonal boron nitride (hBN) induced by isotopic purification are reported. The study extends the purification to N-15 isotopes. Raman and photoluminescence spectroscopies show that the monoisotopic hBN crystals exhibit similar vibrational and optical properties to N-14 purified hBN. The growth of high-quality h(10)B(14)N, h(11)B(14)N, h(10)B(15)N, and h(11)B(15)N crystals opens up new possibilities for thermal conductivity control and advanced functionalities in quantum technologies.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Chen Chen, Yang Hang, Hui Shan Wang, Yang Wang, Xiujun Wang, Chengxin Jiang, Yu Feng, Chenxi Liu, Eli Janzen, James H. Edgar, Zhipeng Wei, Wanlin Guo, Weida Hu, Zhuhua Zhang, Haomin Wang, Xiaoming Xie
Summary: The bandgap of hBN nanoribbons (BNNRs) can be changed by spatial/electrostatic confinement. Water adsorption greatly reduces the bandgap of zigzag-oriented BNNRs (zBNNRs) and can tune their conductance and optical bandgaps.
ADVANCED MATERIALS
(2023)
Article
Physics, Multidisciplinary
Yafei Ren, Qiang Gao, A. H. MacDonald, Qian Niu
Summary: Graphene bilayers exhibit zero-energy flatbands at specific magic twist angles, satisfying a Dirac equation with a non-Abelian SU(2) gauge potential. A semiclassical WKB approximation scheme is developed to analyze these zero-energy solutions, finding values of a dimensionless Planck's constant that correspond closely to numerically determined twist angles.
PHYSICAL REVIEW LETTERS
(2021)
Article
Chemistry, Multidisciplinary
Chao Lei, Bheema L. Chittari, Kentaro Nomura, Nepal Banerjee, Jeil Jung, Allan H. MacDonald
Summary: The study predicts that layer antiferromagnetic bilayers from van der Waals materials exhibit a strong magnetoelectric response, which can be controlled electrically for applications.
Article
Physics, Multidisciplinary
Chunli Huang, Nemin Wei, Allan H. MacDonald
Summary: This study explores the quantized anomalous Hall effect in graphene multilayers with flat moire minibands, and suggests a current-driven mechanism for reversing the sign of the Hall effect in these Chern insulators.
PHYSICAL REVIEW LETTERS
(2021)
Article
Multidisciplinary Sciences
Mattia Angeli, Allan H. MacDonald
Summary: In this paper, a continuum theory of moire minibands in the valence bands of Gamma-valley homobilayers is developed, with benchmarking against large-scale ab initio electronic structure calculations. Due to the emergent D-6 symmetry, low-energy Gamma-valley moire holes are found to differ qualitatively from their K-valley counterparts, with the first three bands realizing different models.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2021)
Editorial Material
Nanoscience & Nanotechnology
Eva Y. Andrei, Dmitri K. Efetov, Pablo Jarillo-Herrero, Allan H. MacDonald, Kin Fai Mak, T. Senthil, Emanuel Tutuc, Ali Yazdani, Andrea F. Young
Summary: Moire systems formed by 2D atomic layers have versatile electrical and optical properties, hosting exotic phenomena like superconductivity, correlated insulator states, and orbital magnetism. In this Viewpoint, researchers studying various aspects of moire materials discuss the most exciting directions in this rapidly expanding field.
NATURE REVIEWS MATERIALS
(2021)
Article
Multidisciplinary Sciences
Liguo Ma, Phuong X. Nguyen, Zefang Wang, Yongxin Zeng, Kenji Watanabe, Takashi Taniguchi, Allan H. MacDonald, Kin Fai Mak, Jie Shan
Summary: This study demonstrates a strongly correlated two-dimensional excitonic insulator ground state in transition metal dichalcogenide semiconductor double layers, providing direct thermodynamic evidence for the state. Capacitance measurements show that the exciton fluid is compressible but charge-incompressible. An exciton phase diagram reveals both the Mott transition and interaction-stabilized quasi-condensation.
Article
Physics, Multidisciplinary
Nicolas Morales-Duran, Nai Chao Hu, Pawel Potasz, Allan H. MacDonald
Summary: Moiré materials in two-dimensional semiconductor heterobilayers are quantum simulators that can simulate unconventional states of matter in Hubbard physics, such as spin liquids, insulating ferromagnets, and superconductors. The interaction between electrons or holes in Moiré materials is more relevant compared to atomic scale systems.
PHYSICAL REVIEW LETTERS
(2022)
Review
Nanoscience & Nanotechnology
Emma C. Regan, Danqing Wang, Eunice Y. Paik, Yongxin Zeng, Long Zhang, Jihang Zhu, Allan H. MacDonald, Hui Deng, Feng Wang
Summary: This Review discusses two approaches for realizing emergent excitonic physics in two-dimensional semiconductor heterostructures: the introduction of a moire superlattice and the formation of an optical cavity.
NATURE REVIEWS MATERIALS
(2022)
Review
Nanoscience & Nanotechnology
Libor Smejkal, Allan H. MacDonald, Jairo Sinova, Satoru Nakatsuji, Tomas Jungwirth
Summary: This review organizes the current understanding of anomalous antiferromagnetic materials that generate a Hall effect and discusses their applications in spintronics, topological condensed matter, and multipole magnetism.
NATURE REVIEWS MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Yongxin Zeng, Allan H. MacDonald
Summary: This paper examines the influence of moiré patterns in semiconductor heterobilayers on exciton and trion states, comparing the differences to the case of excitons and trions in semiconductor quantum dots in the limit of strong moiré modulation potentials. The strategies for using optical properties as quantitative probes of moiré materials and the prospects of utilizing moiré materials to design unique light emitters are discussed.
Article
Materials Science, Multidisciplinary
B. Flebus, A. H. MacDonald
Summary: It has been found in recent experiments that phonons can be deflected by a magnetic field when flowing in response to a thermal gradient, leading to a thermal Hall effect. The ratio of phonon Hall conductivity ??H to the phonon longitudinal conductivity ??L in oxide dielectrics can exceed 10^-3 when phonon mean-free paths are longer than phonon wavelengths. Additionally, the ??H/??L ratio does not strongly depend on temperature. These observations suggest a mechanism related to phonon scattering from defects that break time-reversal symmetry, where Lorentz forces acting on charged defects result in significant skew-scattering amplitudes and related thermal Hall effects.
Article
Materials Science, Multidisciplinary
Yongxin Zeng, Fei Xue, Allan H. MacDonald
Summary: This study investigates the influence of an in-plane magnetic field and Coulomb interactions on the physics of quantum spin Hall insulators. By calculating phase diagrams and discussing possible experimental implications, the study demonstrates the system's instability against the formation of density-wave states when the band hybridization is weak and shows the appearance of distinct density-wave states as the strength of the in-plane magnetic field increases.
Article
Materials Science, Multidisciplinary
Dmitry K. Efimkin, Emma K. Laird, Jesper Levinsen, Meera M. Parish, Allan H. MacDonald
Summary: Recent studies have shown that the absorption properties of moderately doped two-dimensional semiconductors can be described in terms of exciton polarons, which exhibit classical charge-dipole behavior in the long-range limit and are only slightly modified for moderate doping. The dependence on doping can be well captured by a model with a phenomenological contact potential.
Article
Materials Science, Multidisciplinary
Jingtian Shi, Jihang Zhu, A. H. MacDonald
Summary: The quantum anomalous Hall (QAH) effect is sometimes observed in twisted bilayer graphene (tBG) when nearly aligned with an encapsulating hexagonal boron nitride (hBN) layer. The presence or absence of the QAH effect in individual devices is related to the commensurability between graphene/graphene and graphene/hBN moire patterns. The QAH effect is likely to occur when the moire patterns form a supermoire pattern near a commensurate point and have a percolating topologically nontrivial QAH phase.
Article
Materials Science, Multidisciplinary
Michael Vogl, Martin Rodriguez-Vega, Benedetta Flebus, Allan H. MacDonald, Gregory A. Fiete
Summary: Motivated by twisted transition metal dichalcogenide bilayers, a simplified model is studied driven by different forms of monochromatic light. The effects of circularly polarized light in free space and longitudinal light from a waveguide on the twisted system are explored. Varying the frequency and amplitude of the drive can induce topological transitions and profound effects on the layer pseudospin texture.
