Review
Quantum Science & Technology
Nguyen T. Hung, Riichiro Saito
Summary: Researchers have been studying the thermoelectric effects of low-dimensional materials in recent years, making progress through a combination of theory and experiments. Studies have shown that the thermal de Broglie wavelength is crucial for enhancing the power factor.
ADVANCED QUANTUM TECHNOLOGIES
(2021)
Article
Chemistry, Multidisciplinary
David Buckley, Zakhar R. Kudrynskyi, Nilanthy Balakrishnan, Tom Vincent, Debarati Mazumder, Eli Castanon, Zakhar D. Kovalyuk, Oleg Kolosov, Olga Kazakova, Alexander Tzalenchuk, Amalia Patane
Summary: The ability of materials to conduct heat is crucial for various physical phenomena, from thermal management to thermoelectrics. Two-dimensional materials like InSe offer a versatile platform to tailor heat transfer due to their high surface-to-volume ratio and mechanical flexibility. Studies show that 2D InSe exhibits anomalous low thermal conductivity compared to traditional dielectrics, making it a promising candidate for future technologies that require efficient heat dissipation or thermoelectric energy conversion.
ADVANCED FUNCTIONAL MATERIALS
(2021)
Review
Chemistry, Physical
Peilei He, Yue Wu
Summary: Thermoelectric technology can directly convert waste heat into electricity, recent advances in nanotechnology have improved thermoelectric materials' performance, thus increasing their feasibility in industry.
Article
Chemistry, Physical
Kunpeng Yuan, Xiaoliang Zhang, Zheng Chang, Zhonghua Yang, Dawei Tang
Summary: Decoupling electron and phonon transport is beneficial for improving the thermoelectric figure of merit. Layered materials can be used to adjust the thermal conductivity by applying pressure. Applying external pressure can decouple electron and phonon transport and enhance thermoelectric performance.
ACS APPLIED ENERGY MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Gennady M. Gusev, Ze D. Kvon, Alexander D. Levin, Nikolay N. Mikhailov
Summary: The thermoelectric response of 80 nm-thick strained HgTe films in a three-dimensional topological insulator was experimentally studied. An ambipolar thermopower was observed, with the Fermi energy shifting from the conduction band to the valence band. The comparison between theory and experiment showed that the thermopower was mainly due to phonon drag contribution, and the Seebeck coefficient was modified in the region where 2D Dirac electrons coexisted with bulk hole states due to electron-hole scattering.
Article
Materials Science, Multidisciplinary
Yuan Zhi Zhang, Shuai Ling Li, Zhen Li, Shi Yun Lou, Shao Min Zhou
Summary: By introducing Sn doping, the GeTe-based material forms a disordered structure, resulting in reduced thermal conductivity and improved thermoelectric performance.
Article
Physics, Multidisciplinary
Shunran Li, Xiaotong Li, Conrad A. Kocoj, Xiaoqin Ji, Shaofan Yuan, Eleni C. Macropulos, Constantinos C. Stoumpos, Fengnian Xia, Lingling Mao, Mercouri G. Kanatzidis, Peijun Guo
Summary: This study investigates the impact of organic spacers on excitons in 2DHPs through femtosecond pump-probe spectroscopy, revealing two distinct temporal response regimes. Vibrational excitation enhances biexciton emission, indicating the influence of vibrations on exciton confinement and exciton detrapping from defect states.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Condensed Matter
Mohsen Arman Asl, Mohammad Reza Benam, Raheleh Pilevar Shahri, Azra Feyzi, Fariba Kafi
Summary: In this paper, the thermoelectric properties of magnesium oxide in different phases and structures were studied. It was found that the monolayer structure exhibited two small peaks in the Seebeck coefficient, which were not present in the bulk structure. Furthermore, the MgO(100) monolayer showed promising thermoelectric properties at both room temperature and high temperatures.
MICRO AND NANOSTRUCTURES
(2022)
Article
Chemistry, Multidisciplinary
Wenwen Lin, Jiangang He, Xianli Su, Xiaomi Zhang, Yi Xia, Trevor P. Bailey, Constantinos C. Stoumpos, Ganjian Tan, Alexander J. E. Rettie, Duck Young Chung, Vinayak P. Dravid, Ctirad Uher, Chris Wolverton, Mercouri G. Kanatzidis
Summary: TlCuSe is an intrinsic p-type semiconductor with ultralow thermal conductivity and high power factor, resulting in a high figure of merit ZT. The weak chemical bonds and large atomic mass contribute to the low sound velocity and anharmonicity, which helps to suppress lattice thermal conductivity.
ADVANCED MATERIALS
(2021)
Article
Physics, Mathematical
Olivier Piguet
Summary: In the de Broglie-Bohm quantum theory, the trajectory of particles is determined by the flux associated with their wave function. This study focuses on relativistic spin-one-half particles and demonstrates, through numerical calculations, that if the wave function is an eigenfunction of the total angular momentum, the de Broglie-Bohm trajectories, referred to as cycles, start as circles with slowly increasing radius and transition to straight lines after a certain time. The arrival times at a detector and their probability distribution are also calculated. The chosen energy and momentum parameters are in the range of graphene's physics.
JOURNAL OF STATISTICAL PHYSICS
(2023)
Review
Chemistry, Multidisciplinary
Gang Wang, Shiliang Mei, Jinfeng Liao, Wei Wang, Yuxin Tang, Qing Zhang, Zikang Tang, Bo Wu, Guichuan Xing
Summary: Hybrid halide perovskites have garnered significant attention from researchers worldwide for their promising applications in semiconductor optoelectronics. Recent studies have shown that low-dimensional perovskite materials, such as quantum-wells or colloidal nanostructures, exhibit unexpectedly attractive nonlinear optical responses due to quantum confinement and exciton effects. The current state of nonlinear optics for low-dimensional perovskites has been systematically reviewed, analyzing the relationship between confinement effects and nonlinear optics, while discussing future directions and challenges for improving nonlinear optics in these materials.
Review
Chemistry, Multidisciplinary
Mali Zhao, Dohyun Kim, Young Hee Lee, Heejun Yang, Suyeon Cho
Summary: This paper introduces critical advances in the field of quantum sensing of thermopower, ranging from atomic to several-hundred-nanometer scales, and discusses the roles of low-dimensionality, defects, spins, and relativistic effects in optimized power generation. Investigating the microscopic nature of thermopower in quantum materials can provide insights for the design of advanced materials for future thermoelectric applications, while quantum sensing techniques for thermopower can pave the way for practical and novel energy devices towards a sustainable society.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Analytical
Byoung S. Ham
Summary: The highest precision in measurements is achieved through vacuum fluctuations in quantum mechanics, which can be further improved by utilizing nonclassical light to reach sub-shot noise limit. Quantum metrology provides a different solution to precision measurement, offering a more accurate method by using squeezed light or higher-order entangled-photon pairs.
Article
Chemistry, Physical
Ankita Singh, Bishnu Pada Majee, Jay Deep Gupta, Ashish Kumar Mishra
Summary: In this study, we examine the quantum confinement and phonon anharmonicity of different-layered MoS2 materials synthesized via chemical vapor deposition. We explore the contribution of spin-orbit and interlayer couplings both theoretically and experimentally. Additionally, we demonstrate the thermally driven layer-dependent bandgap tunability and analyze the phonon confinement behavior and thermal response of the MoS2 nanostructures.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Materials Science, Multidisciplinary
Min Jin, Siqi Lin, Liang Xue, Weijie Deng, Xiuhong Pan, Xuechao Liu
Summary: Indium selenide (InSe) semiconductor crystal was successfully grown using the ground simulation apparatus of China space station. The crystal growth temperature was controlled at 715 degrees C with a temperature gradient of -30 degrees C/cm. The obtained InSe crystal exhibits gamma-phase structure with space group R3m. The estimated average etching pits density (EPD) is about 104/cm2. Thermal analysis shows positive thermal expansion in the range of 30-500 degrees C, and no volatilization occurs even at high temperatures up to 1000 degrees C. This work not only establishes a reliable process for preparing large-sized InSe single crystal but also provides the foundation for future research in outer space.
Article
Nanoscience & Nanotechnology
Aditya Sood, Jonah B. Haber, Johan Carlstrom, Elizabeth A. Peterson, Elyse Barre, Johnathan D. Georgaras, Alexander H. M. Reid, Xiaozhe Shen, Marc E. Zajac, Emma C. Regan, Jie Yang, Takashi Taniguchi, Kenji Watanabe, Feng Wang, Xijie Wang, Jeffrey B. Neaton, Tony F. Heinz, Aaron M. Lindenberg, Felipe H. da Jornada, Archana Raja
Summary: In this study, lattice dynamics in photoexcited WSe2/WS2 heterostructures were directly visualized using femtosecond electron diffraction. It was found that both WSe2 and WS2 were heated simultaneously on a picosecond timescale, which cannot be explained by phonon transport across the interface. First-principles calculations revealed a fast channel involving layer-hybridized electronic states, enabling phonon-assisted interlayer transfer of photoexcited electrons. Phonons were emitted in both layers on the femtosecond timescale via this channel, consistent with the simultaneous lattice heating observed experimentally. Strong electron-phonon coupling via layer-hybridized electronic states was identified as a novel route for controlling energy transport across atomic junctions.
NATURE NANOTECHNOLOGY
(2023)
Article
Chemistry, Multidisciplinary
Jonas D. D. Ziegler, Yeongsu Cho, Sophia Terres, Matan Menahem, Takashi Taniguchi, Kenji Watanabe, Omer Yaffe, Timothy C. C. Berkelbach, Alexey Chernikov
Summary: 2D hybrid perovskites have attracted significant attention in material research for light-harvesting and -emitting applications. In this study, a method of interfacing ultrathin sheets of perovskites with few-layer graphene and hexagonal boron nitride is demonstrated, enabling gate-tunable control of light emission and absorption. The findings reveal the emergence of both negatively and positively charged excitons, with high binding energies and excellent mobility. This research introduces the physics of interacting mixtures of optical and electrical excitations to the broad family of 2D inorganic-organic nanostructures, highlighting the potential of 2D perovskites as a promising material platform for electrically modulated light-emitters and exciton transistors.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Physical
Minwook Kim, Yeonjae Lee, Sunil Kumar, Dongwoon Kang, Sohee Lee, Van Huy Nguyen, Dinh Cong Nguyen, Syed Hassan Abbas Jaffery, Jongwan Jung, Takashi Taniguchi, Kenji Watanabe, Yongho Seo
Summary: In recent years, there has been extensive research on 2D materials-based heterostructures for fabricating nanodevices. Transition metal dichalcogenides (TMDC), hexagonal boron nitride (hBN), and graphene (Gr) are commonly used materials in these devices. Optoelectronic memory devices based on 2D materials are of particular interest due to their structural flexibility and small device size. This study focuses on the fabrication of a non-volatile optoelectronic memory device using tungsten diselenide (WSe2) and hBN-encapsulated Gr-based heterostructures. The device can be easily controlled by both UV light and an electric field.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Chemistry, Multidisciplinary
Valerie Hsieh, Dorri Halbertal, Nathan R. . Finney, Ziyan Zhu, Eli Gerber, Michele Pizzochero, Emine Kucukbenli, Gabriel R. Schleder, Mattia Angeli, Kenji Watanabe, Takashi Taniguchi, Eun-Ah Kim, Efthimios Kaxiras, James Hone, Cory R. Dean, D. N. Basov
Summary: Twisted van der Waals multilayers are regarded as a rich platform for accessing novel electronic phases. This study proposes that naturally formed stacking domains due to relative twist between layers can act as an additional control knob. The researchers observe selective adhesion of metallic nanoparticles and liquid water at domains with specific stacking configurations and demonstrate the manipulation of nanoparticles can locally reconfigure the moire superlattice.
Article
Chemistry, Multidisciplinary
Yu-Chiang Hsieh, Zhen-You Lin, Shin-Ji Fung, Wen-Shin Lu, Sheng-Chin Ho, Siang-Ping Hong, Sheng-Zhu Ho, Chiu-Hua Huang, Kenji Watanabe, Takashi Taniguchi, Yang-Hao Chan, Yi-Chun Chen, Chung-Lin Wu, Tse-Ming Chen
Summary: By creating atomically flat surface nanostructures in hexagonal boron nitride, we achieve an arbitrary on-chip control of both the strain distribution and magnitude on high-quality molybdenum disulfide. The phonon and exciton emissions vary according to our strain field designs, enabling us to write and draw any photoluminescence color image in a single chip. Our strain engineering also offers a powerful means to alter the strengths and energies of interlayer excitons at room temperature, promising for functional excitonic devices.
Article
Chemistry, Physical
Benjamin A. Foutty, Jiachen Yu, Trithep Devakul, Carlos R. Kometter, Yang Zhang, Kenji Watanabe, Takashi Taniguchi, Liang Fu, Benjamin E. Feldman
Summary: By studying twisted double-bilayer WSe2, we have identified charge-ordered phases at multiple integer and fractional moire fillings. Through experiments with magnetic fields and displacement fields, we have observed spin-polarized ground states and a metal-insulator transition. These results demonstrate the control over spin and valley character in this system.
Article
Multidisciplinary Sciences
Kaining Yang, Xiang Gao, Yaning Wang, Tongyao Zhang, Yuchen Gao, Xin Lu, Shihao Zhang, Jianpeng Liu, Pingfan Gu, Zhaoping Luo, Runjie Zheng, Shimin Cao, Hanwen Wang, Xingdan Sun, Kenji Watanabe, Takashi Taniguchi, Xiuyan Li, Jing Zhang, Xi Dai, Jian-Hao Chen, Yu Ye, Zheng Han
Summary: The authors report the evidence of unconventional correlated insulating states in bilayer graphene/CrOCl heterostructures and demonstrate their application for low-temperature logic inverters. They investigate the heterostructures based on Bernal-stacked bilayer graphene atop few-layered CrOCl, which exhibit an over-1-G omega-resistance insulating state in a widely accessible gate voltage range. By applying an in-plane electric field, heating, or gating, the insulating state can be switched into a metallic state with an on/off ratio up to 10(7).
NATURE COMMUNICATIONS
(2023)
Article
Materials Science, Multidisciplinary
Salvatore Cianci, Elena Blundo, Federico Tuzi, Giorgio Pettinari, Katarzyna Olkowska-Pucko, Eirini Parmenopoulou, Djero B. L. Peeters, Antonio Miriametro, Takashi Taniguchi, Kenji Watanabe, Adam Babinski, Maciej R. Molas, Marco Felici, Antonio Polimeni
Summary: This paper reports the formation of regular arrays of strained hydrogen-filled one-layer-thick micro-domes by H-ion irradiation and lithography-based approaches. By depositing thin hBN flakes on the domes, the dome structure can be preserved, leading to the appearance of intense emission lines from localized excitons, which behave as quantum emitters.
ADVANCED OPTICAL MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Michael D. Randle, Masayuki Hosoda, Russell S. Deacon, Manabu Ohtomo, Patrick Zellekens, Kenji Watanabe, Takashi Taniguchi, Shota Okazaki, Takao Sasagawa, Kenichi Kawaguchi, Shintaro Sato, Koji Ishibashi
Summary: Systems combining superconductors with topological insulators provide a platform for studying Majorana bound states and realizing fault tolerant topological quantum computation. Monolayers of WTe2 possess rare properties, such as being a quantum spin Hall insulator and easily transitioning into a superconducting state. Measurements on gate-defined Josephson weak-link devices made from monolayer WTe2 demonstrate the critical role of 2D superconducting leads in interpreting magnetic interference in the resulting junctions. The reported fabrication procedures offer a straightforward means of producing more devices from this technically challenging material and mark the first step towards versatile all-in-one topological Josephson weak-links using monolayer WTe2.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Rafael Battistella Nadas, Andreij C. Gadelha, Tiago C. Barbosa, Cassiano Rabelo, Thiago de Lourenco e Vasconcelos, Vitor Monken, Ary V. R. Portes, Kenji Watanabe, Takashi Taniguchi, Jhonattan C. Ramirez, Leonardo C. Campos, Riichiro Saito, Luiz Gustavo Cancado, Ado Jorio
Summary: The coherence length (L(c)) of the Raman scattering process in graphene, as determined by spatially coherent tip-enhanced Raman spectroscopy, decreases when the Fermi energy is brought to the neutrality point. This observation is consistent with the concept of the Kohn anomaly within a ballistic transport regime. The observed results can be attributed to either an unusually large variation in the longitudinal optical phonon group velocity (v(g)), which reaches twice the value of the longitudinal acoustic phonon, or changes in the electron energy uncertainty. These properties are important for understanding optical and transport phenomena that may not be observable with other techniques.
Editorial Material
Multidisciplinary Sciences
Qian Song, Connor A. Occhialini, Emre Ergecen, Batyr Ilyas, Danila Amoroso, Paolo Barone, Jesse Kapeghian, Kenji Watanabe, Takashi Taniguchi, Antia S. Botana, Silvia Picozzi, Nuh Gedik, Riccardo Comin
Article
Optics
Tianqi Liu, Qiang Fu, Yuanzhe Li, Xu Han, Shixuan Wang, Takashi Taniguchi, Kenji Watanabe, Dongyang Wan, Qi Zhang, Yingbo Zhao, Zhenhua Ni, Fei Ding, Zhenliang Hu, Xueyong Yuan, Junpen Lu
Summary: In this study, the brightness of WS2-based LEDs is enhanced by introducing self-assembled silver nanoparticles (NPs) on top of the LED. With the assistance of effective transient-mode charge injection, a 2.9-fold electroluminescence (EL) enhancement is observed in the experiment. Full-wave simulations confirm that the improvement comes from the scattering capability of silver NPs.
Article
Optics
Garima Gupta, Kenji Watanabe, Takashi Taniguchi, Kausik Majumdar
Summary: In monolayer transition metal dichalcogenide semiconductors, valley coherence degrades rapidly due to scattering and inter-valley exchange interaction. However, by using a sandwich structure of monolayer MoS2 between top and bottom graphene, fully valley-coherent excitons with high degree of linear polarization are achieved. This is attributed to the suppression in exchange interaction, reduction in exciton lifetime, and operating in the motional narrowing regime.
LIGHT-SCIENCE & APPLICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Shaochun Zhang, Mina Maruyama, Susumu Okada, Mengsong Xue, Kenji Watanabe, Takashi Taniguchi, Kazuki Hashimoto, Yasumitsu Miyata, Ruben Canton-Vitoria, Ryo Kitaura
Summary: This study reports the observation of the photovoltaic effect in a WS2/MoS2 van der Waals heterostructure. Light excitation of WS2/MoS2 at a wavelength of 633 nm leads to a photocurrent without applying bias voltages.
Article
Chemistry, Multidisciplinary
Aparna Parappurath, Bhaskar Ghawri, Saisab Bhowmik, Arup Singha, K. Watanabe, T. Taniguchi, Arindam Ghosh
Summary: The ability to tune the twist angle between different layers of 2D materials has led to the creation of electronic flat bands artificially. In this study, the photoresponse of a few-layer WSe2/tBLG heterostructure was measured, and it was found that the photoresponse is sensitive to the band structure of tBLG. When the Fermi energy is within the low-energy moiré bands, the photoresponse is strongly suppressed, but it can be recovered when the Fermi energy exceeds the moiré band edge due to the photogating effect.
