Article
Multidisciplinary Sciences
Binbin Chen, Nicolas Gauquelin, Nives Strkalj, Sizhao Huang, Ufuk Halisdemir, Minh Duc Nguyen, Daen Jannis, Martin F. Sarott, Felix Eltes, Stefan Abel, Matjaz Spreitzer, Manfred Fiebig, Morgan Trassin, Jean Fompeyrine, Johan Verbeeck, Mark Huijben, Guus Rijnders, Gertjan Koster
Summary: The study presents asymmetric oxide superlattices fabricated on silicon, which exhibit enhanced out-of-plane polarization by utilizing coherent strain. Optical measurements reveal a stronger out-of-plane polarized state in the superlattices. Additionally, the coherent strain suppresses the magnetism of the oxide films.
NATURE COMMUNICATIONS
(2022)
Article
Materials Science, Multidisciplinary
Francisco Sanchez-Ochoa, Alberto Rubio-Ponce, Florentino Lopez-Urias
Summary: External hydrostatic pressure (P) is a controllable and clean method to tune the energy position of van Hove singularities in twisted bilayer graphene (TBLG). This study reveals the ground-state properties of high-angle TBLG with different parities under vertical hydrostatic P. The results demonstrate the importance of external P and parity in the electronic structure of TBLG, and their potential implications in experiments.
Article
Physics, Multidisciplinary
Young Woo Choi, Hyoung Joon Choi
Summary: Graphene moire superlattices exhibit varying electron-phonon coupling strengths in different flat bands, showcasing a correlation between strong electron-phonon coupling and observed robust superconductivity. The presence of sublattice polarization in certain moire flat bands may suppress intersublattice electron-phonon matrix elements, potentially leading to weaker or absent superconductivity. Nonadiabatic superconducting transition temperatures T-c obtained from calculations are in good agreement with experimental results.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Multidisciplinary
QuanSheng Wu, Jianpeng Liu, Yifei Guan, Oleg Yazyev
Summary: The study shows that different configurations of twisted double bilayer graphene exhibit distinct Landau level sequences in the Hofstadter butterfly spectra, reflecting the differences in valley Chern numbers of their flat bands. These differences can be explained by analyzing the distribution of orbital magnetization in momentum space.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Multidisciplinary
Taichi Ogawana, Hidetsugu Sakaguchi
Summary: The research explores the tunneling of Dirac electrons in graphene passing through Cantor-like electrostatic and electromagnetic potentials. The transmission rate can be theoretically expressed by the second kind of Chebyshev polynomial, exhibiting a self-similar structure. Even with the disappearance of Klein tunneling due to the application of a magnetic field, the self-similarity of transmittance is maintained and contributes to the complex behavior of conductance.
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN
(2021)
Article
Physics, Multidisciplinary
J. A. Briones-Torres, R. Perez-Alvarez, S. Molina-Valdovinos, I Rodriguez-Vargas
Summary: This study investigates the thermoelectric response of gated bilayer graphene superlattices (GBGSLs) for the first time. The Seebeck coefficient, power factor, figure of merit, output power and efficiency are analyzed for different temperatures and superlattice structural parameters. The impact of minibands, minigaps, and intrinsic resonances in bilayer graphene structures is also examined. The interplay between minibands and Fano resonances is analyzed as a potential mechanism for improving the thermoelectric response of GBGSLs. The density of states is computed to determine the involvement of electron state redistribution-accumulation in the thermoelectric response of GBGSLs.
Article
Multidisciplinary Sciences
Qiao Li, Bin Cheng, Moyu Chen, Bo Xie, Yongqin Xie, Pengfei Wang, Fanqiang Chen, Zenglin Liu, Kenji Watanabe, Takashi Taniguchi, Shi-Jun Liang, Da Wang, Chenjie Wang, Qiang-Hua Wang, Jianpeng Liu, Feng Miao
Summary: Studying strong electron correlations is essential for advancing condensed matter physics. Recent research has demonstrated that moire heterostructures of van der Waals materials can serve as highly tunable quantum platforms for studying strongly correlated quantum physics. In this study, tunable quantum criticalities are observed in a simulator of the extended Hubbard model with spin-valley isospins in chiral-stacked twisted double bilayer graphene. The results showcase the potential of using this solid-state simulator to explore exotic quantum critical states and behaviors.
Article
Thermodynamics
O. Farzadian, F. Yousefi, C. Spitas, K. Kostas
Summary: In this study, non-equilibrium molecular dynamics simulations were used to investigate phonon heat transport in a two-dimensional superlattice with equal-sized domains of graphene and phagraphene. It was found that the minimum thermal conductivity occurred at a superlattice period of 12.85 nm for ribbons, with a value of 155 W/mK. The minimum thermal conductivity of graphene-phagraphene superlattices is approximately 5% of pure graphene thermal conductivity and 50% of phagraphene thermal conductivity.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Engineering, Electrical & Electronic
Andrei Mantesso Coimbra, Julio Cesar Stacchini de Souza, Milton Brown Do Coutto Filho, Andre Abel Augusto
Summary: This paper presents a flexible and effective network-based methodology for the integrated identification of critical groups of branches, measurements and measuring units in power system state estimation. Tests performed with IEEE benchmark systems show the effectiveness of the proposed approach.
IEEE TRANSACTIONS ON POWER SYSTEMS
(2021)
Article
Materials Science, Multidisciplinary
Pierre A. Pantaleon, Tommaso Cea, Rory Brown, Niels R. Walet, Francisco Guinea
Summary: The study investigates the electronic band structures in different arrangements of graphene layers, finding narrow bands with different topology in all cases, and the strong modification of band structures by long range Coulomb interactions.
Article
Chemistry, Multidisciplinary
Bosai Lyu, Jiajun Chen, Shuo Lou, Can Li, Lu Qiu, Wengen Ouyang, Jingxu Xie, Izaac Mitchell, Tongyao Wu, Aolin Deng, Cheng Hu, Xianliang Zhou, Peiyue Shen, Saiqun Ma, Zhenghan Wu, Kenji Watanabe, Takashi Taniguchi, Xiaoqun Wang, Qi Liang, Jinfeng Jia, Michael Urbakh, Oded Hod, Feng Ding, Shiyong Wang, Zhiwen Shi
Summary: Graphene nanoribbons (GNRs) are promising materials for future nanoelectronic applications, but growing long GNRs on insulating substrates remains a challenge. This study reports the successful epitaxial growth of micrometer-long GNRs on an insulating substrate using nanoparticle-catalyzed chemical vapor deposition.
ADVANCED MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Ming Liu, Ryosuke Senga, Masanori Koshino, Yung-Chang Lin, Kazu Suenaga
Summary: Bilayer graphene exhibits both local and global properties, and through electron energy loss spectroscopy, we have discovered its internal local properties and variations in the core-level van Hove singularity peaks.
Article
Engineering, Multidisciplinary
Marco Pradella
Summary: The Eurachem/CITAC Guide on Uncertainty of Qualitative Results is a valuable resource, but it lacks evaluation of precision and does not address alternative methods for determining uncertainty in qualitative results obtained from quantitative measurements as described in ISO documents.
Article
Physics, Condensed Matter
H. Garcia-Cervantes, A. Lopez-Becerra, R. Rodriguez-Gonzalez, I. Rodriguez-Vargas
Summary: Bandgap engineering in graphene has become a popular research topic due to its relevance in technological applications. In this work, massive-massless graphene superlattices (MMGSLs) were proposed to tune the angle-dependent transmission properties. The results showed trigonometric angular dependence of the transmission gaps and minibands based on the secant function in the entire transmission energy range. It was also observed that the transmission gaps and minibands were well-defined at normal incidence, suggesting MMGSLs as a possibility for bandgap engineering in graphene.
PHYSICA B-CONDENSED MATTER
(2022)
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
Materials Science, Multidisciplinary
S. Hubmann, G. Di Battista, I. A. Dmitriev, K. Watanabe, T. Taniguchi, D. K. Efetov, S. D. Ganichev
Summary: In this study, the infrared photoresistance of twisted bilayer graphene (tBLG) under continuous quantum cascade laser illumination at a frequency of 57.1 THz was observed. The photoresistance exhibited a complex sign-alternating behavior under variations of temperature and back gate voltage, and showed giant resonance-like enhancements at certain gate voltages. The structure of the photoresponse correlated with weaker features in the dark dc resistance, indicating the complex band structure of tBLG. The observed photoresistance was well explained by a bolometric model, suggesting ultrafast thermalization of the photoexcited electron-hole pairs across different temperatures and gate voltages. This study establishes photoresistance as a highly sensitive probe for temperature variations in electronic transport of tBLG.
Article
Physics, Applied
Takato Hotta, Haruna Nakajima, Shohei Chiashi, Taiki Inoue, Shigeo Maruyama, Kenji Watanabe, Takashi Taniguchi, Ryo Kitaurat
Summary: In this study, trions have been successfully confined in a one-dimensional restricted space of a MoSe2 device using carbon nanotube (CNT) gate electrodes. The dry transfer process, including deterministic dry transfer of aligned CNTs, has resulted in an hBN-encapsulated MoSe2 device with CNT back gate electrodes. Applying voltage via CNT gate electrodes significantly alters the PL spectra at the location with CNT gate electrodes, which is not observed at a location without CNT gate electrodes. PL imaging shows that the image contrast from trions along the CNT electrode underneath is linear, indicating the one-dimensional confinement of trions in response to the CNT local gating. The obtained confinement width from the PL image is 5.5 x 10(2) nm, consistent with nanoscale one-dimensional confined trions with diffraction limit broadening. This work demonstrates the electrical control of excitonic states at the nanoscale, leading to potential novel optoelectronic properties and exciton devices in the future.
APPLIED PHYSICS EXPRESS
(2023)
Correction
Multidisciplinary Sciences
Sein Park, Wonjun Lee, Seong Jang, Yong-Bin Choi, Jinho Park, Woochan Jung, Kenji Watanabe, Takashi Taniguchi, Gil Young Cho, Gil-Ho Lee
Article
Chemistry, Multidisciplinary
Souvik Biswas, Aurelie Champagne, Jonah B. Haber, Supavit Pokawanvit, Joeson Wong, Hamidreza Akbari, Sergiy Krylyuk, Kenji Watanabe, Takashi Taniguchi, Albert Davydov, Zakaria Y. Al Balushi, Diana Y. Qiu, Felipe H. da Jornada, Jeffrey B. Neaton, Harry A. Atwater
Summary: This study experimentally investigates the excitonic luminescence properties of monolayer MoTe2 and reveals the temperature dependence and interplay between exciton and trion. The results demonstrate that these properties are influenced by free-carrier screening, Pauli blocking, and band gap renormalization, in agreement with theoretical calculations. These findings contribute to the potential applications of monolayer MoTe2 in near-infrared optoelectronics and photonic devices.
Article
Chemistry, Multidisciplinary
Raj Katti, Harpreet Singh Arora, Olli-Pentti Saira, Kenji Watanabe, Takashi Taniguchi, Keith C. Schwab, Michael Lee Roukes, Stevan Nadj-Perge
Summary: Graphene is a crucial material for bolometry, calorimetry, and photon detection due to its exceptional electronic and thermal properties. However, the physical processes responsible for heat transport from electrons to lattice in graphene are still not well understood. In this study, researchers measured the thermal response of low-disorder graphene encapsulated in hexagonal boron nitride and integrated it within a multiterminal superconducting microwave resonator. Their findings suggest that the thermalization rates of electrons and holes in graphene can be attributed to processes at the graphene-aluminum interface.
Article
Chemistry, Physical
Cequn Li, Yi-Fan Zhao, Alexander Vera, Omri Lesser, Hemian Yi, Shalini Kumari, Zijie Yan, Chengye Dong, Timothy Bowen, Ke Wang, Haiying Wang, Jessica L. Thompson, Kenji Watanabe, Takashi Taniguchi, Danielle Reifsnyder Hickey, Yuval Oreg, Joshua A. Robinson, Cui-Zu Chang, Jun Zhu
Summary: We report on the growth and properties of high-quality (Bi,Sb)(2)Te-3/graphene/gallium heterostructures. Our synthetic approach enables atomically sharp layers at both hetero-interfaces, promoting proximity-induced superconductivity originating in the gallium film. A lithography-free, van der Waals tunnel junction is developed to perform transport tunnelling spectroscopy. We find a robust, proximity-induced superconducting gap formed in the Dirac surface states, and the presence of a single Abrikosov vortex manifesting in discrete conductance changes.
Article
Physics, Multidisciplinary
A. Schmitt, P. Vallet, D. Mele, M. Rosticher, T. Taniguchi, K. Watanabe, E. Bocquillon, G. Feve, J. M. Berroir, C. Voisin, J. Cayssol, M. O. Goerbig, J. Troost, E. Baudin, B. Placais
Summary: Researchers have achieved a mesoscopic variant of the Schwinger effect in graphene transistors, which involves the creation of matter by electric fields. By conducting transport measurements, they observed universal one-dimensional Schwinger conductance at the pinch-off of the transistors. These findings enhance our understanding of current saturation limits in ballistic graphene and open up new directions for quantum electrodynamic experiments in the laboratory.
Article
Multidisciplinary Sciences
Saroj B. Chand, John M. Woods, Jiamin Quan, Enrique Mejia, Takashi Taniguchi, Kenji Watanabe, Andrea Alu, Gabriele Grosso
Summary: This study demonstrates the efficient diffusion of dark excitons in non-uniform materials and their propagation through optical readout, providing a new concept for excitonic device applications in both classical and quantum information technology.
NATURE COMMUNICATIONS
(2023)
Article
Materials Science, Multidisciplinary
Lucja Kipczak, Artur O. Slobodeniuk, Tomasz Wozniak, Mukul Bhatnagar, Natalia Zawadzka, Katarzyna Olkowska-Pucko, Magdalena Grzeszczyk, Kenji Watanabe, Takashi Taniguchi, Adam Babinski, Maciej R. Molas
Summary: Excitons in thin layers of semiconducting transition metal dichalcogenides are highly affected by the modified electron-hole interaction, leading to deviations from the two-dimensional hydrogen atom model. In this study, we experimentally and theoretically investigate excitonic properties in ML and BL MoSe2 encapsulated in hexagonal BN. The magnetic field evolutions of the reflectance contrast spectra were measured, allowing the determination of g-factors for intralayer and interlayer excitons. First principles calculations were used to explain the dependence of g-factors on the number of layers and excitation state. Additionally, the ladder of excitonic s states in the ML could be reproduced using the k.p 2 BL.
Article
Chemistry, Multidisciplinary
Nam Thanh Trung Vu, Leyi Loh, Yuan Chen, Qingyun Wu, Ivan A. A. Verzhbitskiy, Kenji Watanabe, Takashi Taniguchi, Michel Bosman, Yee Sin Ang, Lay Kee Ang, Maxim Trushin, Goki Eda
Summary: Precisely controlled impurity doping is essential in modern semiconductor technologies, and desired properties can be achieved at very low concentrations. However, in two-dimensional semiconductors, the identification and quantification of impurities are challenging due to their dilute limit and the limitations of common analytical techniques. In this study, we utilize conductive atomic force microscopy to rapidly and accurately image dilute single atomic impurities. The local conductivity is enhanced by more than 100-fold due to resonance-assisted tunneling, and the imaging is selective for minority defects. We also demonstrate the detection of subsurface impurities with single monolayer depth resolution in multilayer materials.
Article
Chemistry, Multidisciplinary
Shan-Wen Cheng, Ding Xu, Haowen Su, James M. Baxter, Luke N. Holtzman, Kenji Watanabe, Takashi Taniguchi, James C. Hone, Katayun Barmak, Milan Delor
Summary: In this study, we use excitons in two-dimensional materials as sensors to achieve visible-light imaging of phonon polariton propagation in hexagonal boron nitride, and observe the phenomenon of co-propagation of excitons and phonon polaritons. This research provides a new method for high-precision imaging of polar excitations and a new mechanism for realizing ballistic exciton transport at room temperature.
Article
Physics, Multidisciplinary
Liam A. Cohen, Noah L. Samuelson, Taige Wang, Kai Klocke, Cian C. Reeves, Takashi Taniguchi, Kenji Watanabe, Sagar Vijay, Michael P. Zaletel, Andrea F. Young
Summary: In an all-van der Waals heterostructure, the active layer, gate dielectrics and gate electrodes are assembled from two-dimensional crystals that have a low density of atomic defects. A resist-free local anodic oxidation process allows patterning of sub-100 nm features in graphite gates, and their subsequent integration into an all-van der Waals heterostructure. This technique enables precise control of electrons in two-dimensional materials by eliminating unwanted contamination and introducing nanoscale electrostatic control.
Article
Multidisciplinary Sciences
Samra Husremovic, Berit H. Goodge, Matthew P. Erodici, Katherine Inzani, Alberto Mier, Stephanie M. Ribet, Karen C. Bustillo, Takashi Taniguchi, Kenji Watanabe, Colin Ophus, Sinead M. Griffin, D. Kwabena Bediako
Summary: In this study, researchers demonstrate high-density phase change memory based on phase transition materials. By fabricating H-TaS2/1T-TaS2 heterostructures, they observe optically active heterochirality and correlate it with resistivity steps in the CDW superlattice structure. They also show the role of strain engineering in promoting multi-level switching.
NATURE COMMUNICATIONS
(2023)
Article
Materials Science, Multidisciplinary
T. Johnsen, C. Schattauer, S. Samaddar, A. Weston, M. J. Hamer, K. Watanabe, T. Taniguchi, R. Gorbachev, F. Libisch, M. Morgenstern
Summary: Researchers used scanning tunneling microscopy to investigate the quantum Hall edge states of monolayer graphene and compared the results with theoretical calculations. They found that a proper choice of gate voltage allowed for accurate mapping of the edge state pattern, and observed extended compressible regions, the antinodal structure of edge states, and their meandering along the lateral interface.
Article
Chemistry, Multidisciplinary
Adam Krzysztof Szczerba, Julia Kucharek, Jan Pawlowski, Takashi Taniguchi, Kenji Watanabe, Wojciech Pacuski
Summary: We investigated the possibility of growing a three-dimensional semiconductor on a two-dimensional substrate, and successfully reported for the first time the growth of CdTe quantum wells on hBN using molecular beam epitaxy. The presence of the quantum wells was confirmed through photoluminescence measurements, and it was found that growth on the nearly flat hBN substrate was significantly different from growth on bulk substrates, requiring much lower temperatures.
