Article
Chemistry, Multidisciplinary
Chuyao Tong, Rebekka Garreis, Angelika Knothe, Marius Eich, Agnese Sacchi, Kenji Watanabe, Takashi Taniguchi, Vladimir Fal'ko, Thomas Ihn, Klaus Ensslin, Annika Kurzmann
Summary: Quantum states in graphene have two-fold degeneracy in spins and valleys, which can be utilized for qubit preparations. In bilayer graphene quantum dots, the valley g-factor can be tuned by gate voltage adjustments, resulting in larger g-factor with larger electronic dot sizes. Bipolar operation on the versatile device allows for the observation of transitions from electron dots to hole dots. Addition of gates can extend the system to host tunable double dots.
Article
Nanoscience & Nanotechnology
Francisco A. G. de Lira, Edilberto O. Silva
Summary: An alternative theoretical approach based on the geometry of the states space is proposed to describe the physical properties of a single quantum dot. Analytical expressions for the Fermi energy and density of states were obtained, allowing for the study of electron states and thermodynamic properties of the system. The technique is found to be more suitable for devices with a large number of electrons and provides limitations for the system through magnetic and temperature control. Comparisons with literature results were also conducted.
PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES
(2023)
Article
Chemistry, Multidisciplinary
Marek Korkusinski, Yasser Saleem, Amintor Dusko, Daniel Miravet, Pawel Hawrylak
Summary: We predict the existence of spontaneous spin and valley symmetry-broken states in a gated bilayer graphene quantum dot. By exact diagonalization of the many-body Hamiltonian, we find that the electron system undergoes phase transitions with increasing spin and valley polarizations as the Coulomb interaction strength increases. A phase diagram for N = 1-6 electrons is mapped out as a function of the Coulomb interaction strength.
Article
Chemistry, Multidisciplinary
Zhehao Ge, Dillon Wong, Juwon Lee, Frederic Joucken, Eberth A. Quezada-Lopez, Salman Kahn, Hsin-Zon Tsai, Takashi Taniguchi, Kenji Watanabe, Feng Wang, Alex Zettl, Michael F. Crommie, Jairo Velasco
Summary: The study reported the fabrication and characterization of stadium-shaped quantum dots based on graphene using a scanning tunneling microscope, attributing the absence of quantum chaos features in graphene quantum dots to Klein tunneling.
Article
Physics, Multidisciplinary
Ya-Ning Ren, Yu -Chen Zhuang, Qing-Feng Sun, Lin He
Summary: Combining inhomogeneous pseudomagnetic fields in strained graphene with real magnetic fields can result in valley-contrasting spatial confinement and yield field-tunable valley-polarized confined states. This provides a new approach to manipulate the valley degree of freedom.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Zhehao Ge, Sergey Slizovskiy, Frederic Joucken, Eberth A. Quezada, Takashi Taniguchi, Kenji Watanabe, Vladimir Fal'ko, Jairo Velasco
Summary: Trilayer graphene with Bernal stacking is found to have topological magnetic moments with a large and widely tunable valley g factor, which can be utilized for creating valleytronic devices. The experimental results match well with the theoretical modeling, demonstrating the potential of controlling TLG bands under perpendicular electric and magnetic fields.
PHYSICAL REVIEW LETTERS
(2021)
Article
Materials Science, Multidisciplinary
Ahmal Jawad Zafar, Aranyo Mitra, Vadym Apalkov
Summary: In this study, the electron dynamics of a graphene nanoring in the presence of an ultrashort optical pulse were theoretically investigated. It was found that circularly polarized pulses can induce valley polarization in the graphene nanoring, whereas no valley polarization is observed in a graphene monolayer. The magnitude of the valley polarization in the graphene nanoring depends on the system parameters.
Article
Materials Science, Multidisciplinary
Paulo E. Faria Jr, Thomas Naimer, Kathleen M. McCreary, Berend T. Jonker, Jonathan J. Finley, Scott A. Crooker, Jaroslav Fabian, Andreas Stier
Summary: The valley Zeeman physics of excitons in monolayer transition metal dichalcogenides can provide insights into the spin and orbital degrees of freedom in these materials. The presence of adjacent layers can influence these degrees of freedom due to proximity interactions across the 2D interface. Encapsulating monolayer WS2 in monolayer graphene, we observed variations in the valley Zeeman effect for A-exciton, consistent with expectations from bandgap reduction and graphene-induced dielectric screening. However, the valley Zeeman effect for B-exciton behaved differently and was found to be influenced by the lower conduction band of WS2 at the K/K' valleys.
Article
Chemistry, Multidisciplinary
Yueh-Chun Wu, Takashi Taniguchi, Kenji Watanabe, Jun Yan
Summary: Monolayer transition metal dichalcogenide semiconductors are promising valleytronic materials, and the valley polarized holes are particularly interesting due to their long valley lifetime preserved by the large spin-orbit splitting and spin-valley locking.
Article
Nanoscience & Nanotechnology
Longxing Chi, Jun Nogami, Chandra Veer Singh
Summary: This research reports a phase transition-induced quantum dot system at the nanoscale, providing a new strategy for further downsizing of electronic devices.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Physics, Condensed Matter
A. C. L. Moreira, L. S. Marques
Summary: In this work, the charge transport through a nanostructure composed by a double quantum dot was theoretically studied in two different ways: as a single junction (SJ) and a double junction (DJ). Despite starting with different general formulae for transmission, the results obtained with SJ and DJ treatment were shown to be identical for a minimum two-level model system. Finally, a minimal model for a biphenyl system was analyzed in terms of a SJ point of view using both treatments.
PHYSICA B-CONDENSED MATTER
(2021)
Article
Chemistry, Multidisciplinary
Kaixiang Chen, Chufan Zhang, Xiaoxian Zang, Fuyuan Ma, Yuanzhen Chen, Yaping Dan
Summary: Coating graphene with quantum dots enhances light absorption and leads to high photogain. Light illumination narrows down the surface depletion region, creating a photovoltage that gates the graphene, resulting in high photogain in graphene.
Article
Optics
Mostafa Taghizadeh, Forough Bozorgzadeh, Gholam Hossein Bordbar
Summary: In recent years, there has been significant progress in graphene optoelectronics. The tunable electronic structure of graphene has enabled the development of the next generation carbon-based nano-photonic devices. This study demonstrates the potential of landau-quantized graphene as a platform for a 2D laser-induced grating with high diffraction efficiency in the far-field regime. By considering a doped graphene monolayer and a terahertz field, the researchers simulated electromagnetically induced Fraunhofer diffraction patterns and investigated the conditions for maximum diffraction efficiency. They also explored the coherent control and ultrafast all-optical switching of the probe beam. This proposed system has potential applications in integrated nano-photonic devices for optical communications, infrared spectroscopy, astronomy, optical sensing, and all-optical switching processes.
OPTICS AND LASER TECHNOLOGY
(2023)
Article
Nanoscience & Nanotechnology
Changcheng Zhang, Shuo Zhang, Yifeng Lin, Junguang Tao, Lixiu Guan
Summary: Research shows that valley splitting can be activated in SnO through the magnetic proximity effect with EuBrO, making SnO a promising material for future valleytronics applications. This unique electronic structure in SnO/EuBrO has the potential to lead to the design of new spintronic devices with enhanced valley splitting.
Article
Materials Science, Multidisciplinary
Zhenyan Xu, Xianfeng Zhao, Xiao Xu Yan, Huidan Lu, Yongping Liu
Summary: In this study, GQDs/WO3 composite porous photoanodes were fabricated using a pulsed anodization method, showing significant enhancement in photoelectrochemical performance and excellent PEC stability. This research is of great importance for the realization of solar water splitting.
FUNCTIONAL MATERIALS LETTERS
(2023)
Article
Multidisciplinary Sciences
P. Robin, T. Emmerich, A. Ismail, A. Nigues, Y. You, G. -H. Nam, A. Keerthi, A. Siria, A. K. Geim, B. Radha, L. Bocquet
Summary: Experiments reveal the emergence of memory in the transport of electrolytes across nanoscale channels, which lays the foundation for biomimetic computations.
Article
Nanoscience & Nanotechnology
Pengru Huang, Ruslan Lukin, Maxim Faleev, Nikita Kazeev, Abdalaziz Rashid Al-Maeeni, Daria V. Andreeva, Andrey Ustyuzhanin, Alexander Tormasov, A. H. Castro Neto, Kostya S. Novoselov
Summary: Modification of physical properties and design of materials with on-demand characteristics is crucial in modern technology. Machine learning methods are applied to these systems due to the difficulty in modeling designer materials. A new platform is developed for implementing machine learning techniques in materials design, utilizing datasets on pristine and defected materials.
NPJ 2D MATERIALS AND APPLICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Elena Titova, Dmitry Mylnikov, Mikhail Kashchenko, Ilya Safonov, Sergey Zhukov, Kirill Dzhikirba, Kostya S. Novoselov, Denis A. Bandurin, Georgy Alymov, Dmitry Svintsov
Summary: Graphene's high carrier mobility, compatibility with on-chip waveguides and transistors, and small heat capacitance make it a promising material for the detection of terahertz (THz) radiation. However, the weak reaction of graphene's physical properties to the detected radiation is due to the absence of a band gap. This study investigates the effect of electrically induced band gap on THz detection in graphene bilayer with split-gate p-n junction, and demonstrates that the induction of a band gap leads to increased current and voltage responsivities.
Article
Chemistry, Multidisciplinary
Dali Ji, Yunah Lee, Yuta Nishina, Kazuhide Kamiya, Rahman Daiyan, Dewei Chu, Xinyue Wen, Masamichi Yoshimura, Priyank Kumar, Daria V. Andreeva, Kostya S. Novoselov, Gwan-Hyoung Lee, Rakesh Joshi, Tobias Foller
Summary: This study introduces a simple electrochemical method utilizing the angstrom confinement of laminar rGO nanochannels to achieve atomically thin transition metal oxides. The method allows for sub-unit-cell growth of 2D-TMO and demonstrates a balance between high activity and stability.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
M. Grzeszczyk, S. Acharya, D. Pashov, Z. Chen, K. Vaklinova, M. van Schilfgaarde, K. Watanabe, T. Taniguchi, K. S. Novoselov, M. I. Katsnelson, M. Koperski
Summary: It is discovered that despite similar structural and magnetic configurations, the coupling between excitons and magnetization is qualitatively different in CrBr3 and CrI3 films. Through a combination of optical spin pumping experiments and state-of-the-art theory, it is concluded that the hole-magnetization coupling has the opposite sign in CrBr3 and CrI3, as well as between the ground and excited exciton state. Efficient spin pumping capabilities are demonstrated in CrBr3 driven by magnetization via spin-dependent absorption, and the different origins of the magnetic hysteresis in CrBr3 and CrI3 are unraveled.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Physical
Mariana C. F. Costa, Pei Rou Ng, Sergey Grebenchuck, Jun You Tan, Gavin K. W. Koon, Hui Li Tan, Colin R. Woods, Ricardo K. Donato, Kostya S. Novoselov, Antonio H. Castro Neto
Summary: One of the important characteristics of 2D electrolytes is their ability to transform into 1D structures like nanoscrolls. However, these 1D structures are soft, unstable, and have poor electrical conductivity. Through the use of atomic force microscopy and electrical transport measurements, researchers have found that one-step, catalyst-free graphitization of graphene nanoscrolls enhances their structural stability and reduces their structural disorder. These changes in physical properties open up possibilities for the study of exotic materials and various industrial applications.
Article
Chemistry, Physical
Xuanye Leng, Ricardo J. Vazquez, Samantha R. McCuskey, Glenn Quek, Yude Su, Konstantin G. Nikolaev, Mariana C. F. Costa, Siyu Chen, Musen Chen, Kou Yang, Jinpei Zhao, Mo Lin, Zhaolong Chen, Guillermo C. Bazan, Kostya S. Novoselov, Daria V. Andreeva
Summary: The high electrical conductivity and low dimensionality of graphene are crucial for lightweight bioanodes in new-generation energy technologies. However, integrating graphene in biointerfaces is challenging due to its incompatible surface energy with living matter. We propose a sustainable chemical control method to achieve the desired surface hydrophilicity and conductivity of graphene nanowalls, enabling the formation of a lightweight, graphene-based, sponge bioanode. This novel graphene-based material shows stable and rapid response, with a biocurrent density of 135.35 mA m(-2) achieved within a few hours.
Article
Chemistry, Multidisciplinary
James E. E. Nunn, Andrew McEllistrim, Astrid Weston, Aitor Garcia-Ruiz, Matthew D. D. Watson, Marcin Mucha-Kruczynski, Cephise Cacho, Roman V. V. Gorbachev, Vladimir I. I. Fal'ko, Neil R. R. Wilson
Summary: Researchers used angle-resolved photoemission spectroscopy to study the twist-dependent band structure of twisted-graphene layers, validating models and revealing field-induced gaps. However, a discrepancy was found in the gap between the flat band and the next valence band in tDBG, indicating lattice relaxation in this regime.
Article
Multidisciplinary Sciences
Na Xin, James Lourembam, Piranavan Kumaravadivel, A. E. Kazantsev, Zefei Wu, Ciaran Mullan, Julien Barrier, Alexandra A. Geim, I. V. Grigorieva, A. Mishchenko, A. Principi, V. I. Fal'ko, L. A. Ponomarenko, A. K. Geim, Alexey I. Berdyugin
Summary: The most distinctive feature of graphene is its electronic spectrum, in which the Dirac point is located. At low temperatures, the intrinsic behavior of this spectrum is often hidden by charge inhomogeneity, but thermal excitations can overcome the disorder at higher temperatures and create an electron-hole plasma. The behavior of this plasma in magnetic fields is not well understood at present.
Article
Multidisciplinary Sciences
Ye-Chuang Han, Jun Yi, Beibei Pang, Ning Wang, Xu-Cheng Li, Tao Yao, Kostya S. Novoselov, Zhong-Qun Tian
Summary: A novel graphene-confined ultrafast radiant heating (GCURH) method is developed to synthesize high-loading metal cluster catalysts in microseconds, overcoming the trade-off between ultrasmall size and high loading. The graphene acts as a diffusion-constrained nanoreactor, providing kinetics-dominant and diffusion-constrained conditions for the synthesis of subnanometer metal clusters.
NATIONAL SCIENCE REVIEW
(2023)
Correction
Nanoscience & Nanotechnology
Pengru Huang, Ruslan Lukin, Maxim Faleev, Nikita Kazeev, Abdalaziz Rashid Al-Maeeni, Daria V. Andreeva, Andrey Ustyuzhanin, Alexander Tormasov, A. H. Castro Neto, Kostya S. Novoselov
NPJ 2D MATERIALS AND APPLICATIONS
(2023)
Article
Chemistry, Physical
Kendon Shirley, Hsinhan Tsai, Nicholas Cucciniello, Jonathan Bird, Quanxi Jia, Elias Torres, Phil Butler, Anthony Butler, Jerome Crocco, Eslam Taha, Abdulsalam Alhawsawi, Jessica Germino, Maoz Dor, Chaochao Dun, Omer Firat, Jared Parker, Matt Graham, Kostya S. Novoselov, Wanyi Nie
Summary: We have developed a recyclable perovskite-graphene heterostructure for high-performance X-ray detection in medical imaging. The graphene pixel maintains high mobility even after perovskite deposition, enabling efficient conversion for ultrahigh sensitivity. By increasing the operational bias of the graphene channel, the signal-to-noise ratio of X-ray detection can be significantly improved. The perovskite layer can be easily washed off without damaging the graphene, making our heterostructure X-ray detector recyclable.
ACS ENERGY LETTERS
(2023)
Article
Chemistry, Physical
Nikita Kazeev, Abdalaziz Rashid Al-Maeeni, Ignat Romanov, Maxim Faleev, Ruslan Lukin, Alexander Tormasov, A. H. Castro Neto, Kostya S. Novoselov, Pengru Huang, Andrey Ustyuzhanin
Summary: Two-dimensional materials offer a promising platform for next-generation electronic devices and high-tech applications. We propose a machine learning approach to estimate the properties of 2D materials based on their lattice structure and defect configuration, allowing for rapid tuning of material properties. Our methodology outperforms state-of-the-art approaches in terms of energy prediction accuracy and resource efficiency.
NPJ COMPUTATIONAL MATERIALS
(2023)
Article
Physics, Multidisciplinary
Evgenii E. Vdovin, Mark T. Greenaway, Yurii N. Khanin, Sergey V. Morozov, Oleg Makarovsky, Amalia Patane, Artem Mishchenko, Sergey Slizovskiy, Vladimir I. Fal'ko, Andre K. Geim, Kostya S. Novoselov, Laurence Eaves
Summary: Insights into the fundamental properties of graphene's Dirac-Weyl fermions have been gained through studying electron tunnelling transistors with an atomically thin layer of hexagonal boron nitride (hBN) sandwiched between two layers of high purity graphene. With the presence of a single defect within the hBN tunnel barrier, electrons can be injected into the graphene layers, and its well-defined energy level acts as a high resolution spectroscopic probe of electron-electron interactions in graphene. We observe a magnetic field dependent suppression of the tunnel current flowing through a single defect below temperatures of about 2 K, attributed to the formation of a magnetically-induced Coulomb gap in the spectral density of electrons tunnelling into graphene due to electron-electron interactions.
COMMUNICATIONS PHYSICS
(2023)
Article
Engineering, Electrical & Electronic
Wendong Wang, Nicholas Clark, Matthew Hamer, Amy Carl, Endre Tovari, Sam Sullivan-Allsop, Evan Tillotson, Yunze Gao, Hugo de Latour, Francisco Selles, James Howarth, Eli G. Castanon, Mingwei Zhou, Haoyu Bai, Xiao Li, Astrid Weston, Kenji Watanabe, Takashi Taniguchi, Cecilia Mattevi, Thomas H. Bointon, Paul V. Wiper, Andrew J. Strudwick, Leonid A. Ponomarenko, Andrey V. Kretinin, Sarah J. Haigh, Alex Summerfield, Roman Gorbachev
Summary: We report a polymer-free technique for assembling van der Waals heterostructures using flexible silicon nitride membranes. This technique allows the fabrication of high-quality heterostructures in harsher environmental conditions, resulting in improved electronic and optoelectronic behavior. Specifically, we demonstrate the improved homogeneity of moire superlattices in twisted-graphene heterostructures assembled using this technique.
NATURE ELECTRONICS
(2023)