Article
Chemistry, Multidisciplinary
Dongheon Lee, Kyung-Hwan Jin, Feng Liu, Han Woong Yeom
Summary: In this study, we propose a theoretical approach to realize artificial lattices on a 2D Mott insulator, which can offer a condensed-matter platform to explore the interplay between correlated topological orders and superconductivity.
Article
Chemistry, Multidisciplinary
Qirong Yao, Jae Whan Park, Eunseok Oh, Han Woong Yeom
Summary: Despite limited control over the electronic properties of individual domain walls in various materials with broken symmetries, a chemical method using indium adatoms on 1T tantalum disulfide is introduced to tune the electronic properties of domain walls. Experimental observations show distinct behaviors of the adatoms on domains with different terminations, forming chains along the edges of neighboring domains. Density functional theory calculations reveal a 1D Mott insulating state on a modified domain wall, suggesting the potential for widely tuning local electronic states in domain walls and 2D materials through chemical decoration by adsorbates.
Article
Materials Science, Multidisciplinary
Tanusree Saha, Arindam Pramanik, Barbara Ressel, Alessandra Ciavardini, Fabio Frassetto, Federico Galdenzi, Luca Poletto, Arun Ravindran, Primoz Rebernik Ribic, Giovanni De Ninno
Summary: This study investigates the photoinduced transient phase and ground state recovery dynamics in the complex material 1T-TaS2 using femtosecond time- and angle-resolved photoemission spectroscopy. The results reveal similarities between the band structures of the transient and equilibrium phases, with evidence for coexistence of the Mott insulating and metallic phases. The study also finds that the recoveries of Mott and CDW orders begin simultaneously, highlighting their coupling. Additionally, a metastable phase is observed during the recovery process, which is driven by the CDW lattice order.
Article
Chemistry, Multidisciplinary
Ewa M. Lacinska, Magdalena Furman, Johannes Binder, Iaroslav Lutsyk, Pawel J. Kowalczyk, Roman Stepniewski, Andrzej Wysmolek
Summary: In this study, it was discovered through experiments that 1T-TaS2 exhibits Raman optical activity (ROA) under laser excitation, providing strong evidence for its chirality. The results suggest that ROA may serve as a universal tool for studying the chiral properties of quantum materials.
Article
Materials Science, Multidisciplinary
Jae Whan Park, Jinwon Lee, Han Woong Yeom
Summary: This study identifies the atomic and electronic structures of various discommensuration domain walls in 1T-TaS2 quenched metastably with nanoscale domain wall networks through scanning tunneling microscope and density functional theory calculations. The domain walls exhibit different in-gap states, with metallic states appearing only in certain types of domain walls. This work provides insights for engineering the functionality of domain walls in correlated van der Waals materials.
NPJ QUANTUM MATERIALS
(2021)
Article
Materials Science, Multidisciplinary
Yanyan Geng, Le Lei, Haoyu Dong, Jianfeng Guo, Shuo Mi, Yan Li, Li Huang, Fei Pang, Rui Xu, Weichang Zhou, Zheng Liu, Wei Ji, Zhihai Cheng
Summary: This study reports a sequence of spatial electronic phase transitions in 1T-TaS2 within the temperature range of 160-230 K, revealing several emergent electronic states during the CCDW-TCDW phase transitions. The competition and cooperation among stacking-dependent interlayer interactions, intralayer electron-electron correlations, and electron-phonon coupling are found to play important roles in these phase transitions, providing insights into understanding the hysteretic electronic phase transitions in correlated CDW state and exploring exotic quantum states in correlated materials.
Article
Chemistry, Physical
Wenhao Zhang, Degong Ding, Jingjing Gao, Kunliang Bu, Zongxiu Wu, Li Wang, Fangsen Li, Wei Wang, Xuan Luo, Wenjian Lu, Chuanhong Jin, Yuping Sun, Yi Yin
Summary: Intercalation is an effective method to modify physical properties and induce novel electronic states of transition metal dichalcogenide materials. In this study, the successful synthesis of copper-intercalated 1T-TaS2 is reported, and the structural and electronic modifications are characterized using various techniques. The intercalated copper atom suppresses the commensurate charge density wave phase and two specific electronic modulations are discovered in the near-commensurate charge density wave phase.
Article
Nanoscience & Nanotechnology
Gan Liu, Tianyu Qiu, Kuanyu He, Yizhou Liu, Dongjing Lin, Zhen Ma, Zhentao Huang, Wenna Tang, Jie Xu, Kenji Watanabe, Takashi Taniguchi, Libo Gao, Jinsheng Wen, Jun-Ming Liu, Binghai Yan, Xiaoxiang Xi
Summary: In this study, electrical switching of ferro-rotational domain states in the charge-density-wave phases of nanometre-thick 1T-TaS2 crystals is demonstrated. Despite the lack of coupling between the electric field and the ferroic order due to symmetry mismatch, the electric field drives domain wall propagation, resulting in reversible, durable, and non-volatile isothermal state switching.
NATURE NANOTECHNOLOGY
(2023)
Article
Materials Science, Multidisciplinary
Jingwei Dong, Dongbin Shin, Ernest Pastor, Tobias Ritschel, Laurent Cario, Zhesheng Chen, Weiyan Qi, Romain Grasset, Marino Marsi, Amina Taleb-Ibrahimi, Noejung Park, Angel Rubio, Luca Perfetti, Evangelos Papalazarou
Summary: We used angle and time-resolved photoelectron spectroscopy to study the commensurate charge density wave (CDW) phase of 1T-TaS2. We employed different probe pulse polarizations to map the dispersion of electronic states above and below the chemical potential. Upon photoexcitation, the fluctuations of CDW order erased the band dispersion and squeezed the electronic states near the chemical potential. This transient phase developed within half a period of coherent lattice motion and was influenced by strong electronic correlations. Our simulations indicated that the screening of Coulomb repulsion depended on the stacking order of the TaS2 layers. The entanglement of these degrees of freedom suggested that both the structural order and electronic repulsion were locally modified by the photoinduced CDW fluctuations.
Article
Physics, Multidisciplinary
Francesco Petocchi, Christopher W. Nicholson, Bjoern Salzmann, Diego Pasquier, Oleg Yazyev, Claude Monney, Philipp Werner
Summary: We address the problem of the ground state of 1T-TaS2 by studying the correlated electronic structure of stacked bilayers. The surface termination determines whether the uncorrelated system is band insulating or exhibits a metallic surface state. A Mott gap opens in the surface state but is smaller than the gap originating from the bilayer structure. Our results are consistent with recent experimental measurements and clarify the interplay between Mott insulating and band insulating behavior in this system.
PHYSICAL REVIEW LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Li Cheng, Xuanyu Long, Xiaobin Chen, Xiaolong Zou, Zheng Liu
Summary: The study shows that a flat band in 1T-TaS2 can be understood by adjusting the t(2g) basis, and the rehybridization of three orbitals by the CDW order leads to the formation of the flat band.
Article
Chemistry, Multidisciplinary
Gang Wang, Xixi Yu, Erding Zhao, Daiyue Li, Le Wang, Junhao Lin
Summary: In this study, aberration-corrected cryogenic transmission electron microscopy (cryo-TEM) was used to investigate the in-and out-of-plane ordering of the commensurate charge density wave (CDW) superstructure in a 1T-TaS2 thin flake. By analyzing the phase intensity variation of modulated Ta atoms, a penetrative 3D CDW stacking structure with an intertwining multidomain structure was visualized, revealing three types of vertical CDW stacking configurations. This research provides microstructural evidence for the coexistence of local Mott insulation and metal phases and offers a paradigm for studying CDW structure and correlation order in condensed-matter physics using cryo-TEM.
Article
Chemistry, Physical
Rui Wang, Junbo Zhou, Xinsheng Wang, Liming Xie, Jimin Zhao, Xiaohui Qiu
Summary: Study shows that 1T-TaS2 nanoflakes undergo a phase transition from commensurate CDW to nearly commensurate CDW state around 210K, with the phase transition stiffness depending on thickness. Thinner nanoflakes exhibit a smaller phase transition stiffness due to increased fluctuations, inhibiting the nucleation and growth of discommensurations. The results suggest that carrier dynamics could be an efficient method to study quantum phase transition in correlated materials.
Article
Materials Science, Multidisciplinary
Jingwei Dong, Weiyan Qi, Dongbin Shin, Laurent Cario, Zhesheng Chen, Romain Grasset, Davide Boschetto, Mateusz Weis, Pierrick Lample, Ernest Pastor, Tobias Ritschel, Marino Marsi, Amina Taleb, Noejung Park, Angel Rubio, Evangelos Papalazarou, Luca Perfetti
Summary: This study compares the bulk and surface properties of the transition metal dichalcogenide 1T-TaS2. It is found that when heating the sample, the surface exhibits an intermediate insulating phase while the bulk remains metallic. The amplitude mode at the surface is always stiffer and shows variable coupling to the Mott-Peierls band in different phases.
Article
Chemistry, Physical
Borgea G. M. Ekoya, Jinkun Han, Junqiang Zhu, Yabing Shan, Ran Liu, Laigui Hu, Zhi-Jun Qiu, Chunxiao Cong
Summary: The collapse of charge density wave (CDW) states in few-layer 2H-TaS2 induced by the interaction with rhodamine 6G (R6G) was investigated using Raman spectroscopy. It was found that the CDW states disappeared in few-layer 2H-TaS2 with R6G adsorbed due to charge transfer. This study provides insights into the mechanisms of CDW states and the control of CDW states under different environmental conditions.
Review
Chemistry, Multidisciplinary
Xiaodong Yan, Justin H. Qian, Vinod K. Sangwan, Mark C. Hersam
Summary: The increasing importance of artificial intelligence has led to the development of neuromorphic circuits that aim to replicate the energy-efficient information processing of the brain. This review provides a conceptual overview of memtransistors in the context of neuromorphic circuits and surveys recent progress in this field. The different materials systems and device architectures are classified based on their control and tunability of synaptic behavior, with a focus on nanomaterials and their unique properties. Strategies for wafer-scale integration and materials challenges for practical neuromorphic circuits are also discussed.
ADVANCED MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Jiangbin Wu, Yu Yao, Miao-Ling Lin, Malte Rosner, Zhonghao Du, Kenji Watanabe, Takashi Taniguchi, Ping-Heng Tan, Stephan Haas, Han Wang
Summary: In this work, the spin-phonon coupling (SPC) in monolayer chromium tribromide is investigated using Raman spectroscopy and first principle calculations. The experimental and numerical results show good agreement in terms of Curie temperature and phonon shifts. It is demonstrated how magnetic exchange interactions affect phonon vibrations, providing design fundamentals for 2D magnetic materials and related devices.
ADVANCED MATERIALS
(2022)
Review
Chemistry, Multidisciplinary
Jiahui Ma, Hefei Liu, Ning Yang, Jingyi Zou, Sen Lin, Yuhao Zhang, Xu Zhang, Jing Guo, Han Wang
Summary: Memory technologies and applications using emerging 2D materials have gained increasing attention in recent years. This article provides an overview of progress in 2D-material-based memory technologies and applications at the circuit level. It discusses the growth and fabrication methods, reviews integrated memory circuits, compares experimental implementations with theoretical estimations, summarizes in-memory computing applications, and identifies challenges and possible approaches for more reliable system-level fabrication.
ADVANCED MATERIALS
(2022)
Article
Chemistry, Physical
Boyang Zhao, Md Shafkat Bin Hoque, Gwan Yeong Jung, Hongyan Mei, Shantanu Singh, Guodong Ren, Milena Milich, Qinai Zhao, Nan Wang, Huandong Chen, Shanyuan Niu, Sang-Jun Lee, Cheng-Tai Kuo, Jun-Sik Lee, John A. Tomko, Han Wang, Mikhail A. Kats, Rohan Mishra, Patrick E. Hopkins, Jayakanth Ravichandran
Summary: Low-dimensional materials, such as chain-like or layered structures, exhibit significant anisotropic electrical, optical, and thermal properties. BaTiS3 (BTS), a material with a chain-like structure, has been found to possess giant in-plane optical anisotropy and glass-like thermal conductivity. By characterizing BTS crystals with different orientations, it is revealed that BTS has strong optical and thermal anisotropy.
CHEMISTRY OF MATERIALS
(2022)
Article
Engineering, Electrical & Electronic
Yunwei Ma, Ming Xiao, Zhonghao Du, Lei Wang, Eric Carlson, Louis Guido, Han Wang, Lai Wang, Yi Luo, Yuhao Zhang
Summary: This study addresses the activation of buried p-GaN layers in emerging GaN devices. It is found that the breakdown E-field and leakage current of sidewall-activated p-GaN layer are determined by the edge area with the highest activation efficiency. The leakage mechanism follows the trap-assisted tunneling model. These findings provide critical information for the design and processing of advanced GaN devices.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Chemistry, Multidisciplinary
Jiangbin Wu, Nan Wang, Ya-Ru Xie, Hefei Liu, Xinghao Huang, Xin Cong, Hung-Yu Chen, Jiahui Ma, Fanxin Liu, Hangbo Zhao, Jun Zhang, Ping-Heng Tan, Han Wang
Summary: This research reports the extraordinary mechanical properties of the newly discovered inorganic double helical semiconductor tin indium phosphate, which has the lowest Young's modulus and large elastic and plastic bending strains. These results are of great significance for understanding the mechanical properties of the material and its potential applications in flexible electronics and nanomedicine.
Review
Chemistry, Multidisciplinary
Hefei Liu, Yuan Qin, Hung-Yu Chen, Jiangbin Wu, Jiahui Ma, Zhonghao Du, Nan Wang, Jingyi Zou, Sen Lin, Xu Zhang, Yuhao Zhang, Han Wang
Summary: This paper reviews the progress of artificial neuronal devices based on emerging volatile switching materials, focusing on the demonstrated neuron models implemented in these devices and their utilization for computational and sensing applications. Furthermore, it discusses the inspirations from neuroscience and engineering methods to enhance the neuronal dynamics that are yet to be realized in artificial neuronal devices and networks towards achieving the full functionalities of biological neurons.
ADVANCED MATERIALS
(2023)
Article
Physics, Applied
John M. Cain, Xiaodong Yan, Stephanie E. Liu, Justin H. Qian, Thomas T. Zeng, Vinod K. Sangwan, Mark C. Hersam, Stanley S. Chou, Tzu-Ming Lu
Summary: Sulfur-deficient polycrystalline two-dimensional molybdenum disulfide memtransistors demonstrate gate-tunable memristive switching for new memory operations and neuromorphic computing paradigms. The influence of grain boundaries, sulfur vacancies, and surface interactions on defect-related kinetics that produces memristive switching is studied using current transient measurements. It is observed that adsorbed water molecules alter the resistive switching kinetics by suppressing the electronic trap-filling processes.
APPLIED PHYSICS LETTERS
(2023)
Article
Multidisciplinary Sciences
Mingyi Rao, Hao Tang, Jiangbin Wu, Wenhao Song, Max Zhang, Wenbo Yin, Ye Zhuo, Fatemeh Kiani, Benjamin Chen, Xiangqi Jiang, Hefei Liu, Hung-Yu Chen, Rivu Midya, Fan Ye, Hao Jiang, Zhongrui Wang, Mingche Wu, Miao Hu, Han Wang, Qiangfei Xia, Ning Ge, Ju Li, J. Joshua Yang
Summary: Neural networks based on memristive devices have the potential to improve throughput and energy efficiency in machine learning and artificial intelligence, especially in edge applications. To commercialize edge applications, it is practical to download synaptic weights from cloud training and program them into memristors. High-precision programmability is required for memristors in neural network applications to ensure uniform and accurate performance across multiple networks.
Article
Engineering, Electrical & Electronic
Yuan Qin, Ming Xiao, Matthew Porter, Yunwei Ma, Joseph Spencer, Zhonghao Du, Alan G. Jacobs, Kohei Sasaki, Han Wang, Marko Tadjer, Yuhao Zhang
Summary: This study presents a lateral Ga2O3 Schottky barrier diode (SBD) with a record-breaking breakdown voltage (BV) of over 10 kV. The 10 kV SBD exhibits excellent thermal stability up to 200 degrees C, making it one of the highest operational temperatures achieved for Ga2O3 devices at multi-kilovolt levels. The key to achieving such high BV lies in the reduced surface field (RESURF) structure based on p-type nickel oxide (NiO), which effectively balances the depletion charges in the n-Ga2O3 channel at high voltage.
IEEE ELECTRON DEVICE LETTERS
(2023)
Review
Engineering, Electrical & Electronic
Mengjiao Li, Hefei Liu, Ruoyu Zhao, Feng-Shou Yang, Mingrui Chen, Ye Zhuo, Chongwu Zhou, Han Wang, Yen-Fu Lin, J. Joshua Yang
Summary: This review examines the switching mechanisms in memristive devices based on van der Waals materials, highlighting their potential advantages and the challenges that must be addressed for their use in next-generation electronic and computing applications. The modulation of structural defects or compositional impurities, also known as imperfections, mainly drives the memristive switching processes in these devices. The study explores how imperfections in van der Waals materials create different switching mechanisms, allowing for opportunities to engineer the switching behavior in memristive devices. The challenges of material selection, mechanism investigation, and switching uniformity control are discussed, along with the potential application of van der Waals memristors in efficient computing technologies at the system level.
NATURE ELECTRONICS
(2023)
Article
Engineering, Electrical & Electronic
Xiaodong Yan, Justin H. Qian, Jiahui Ma, Aoyang Zhang, Stephanie E. Liu, Matthew P. Bland, Kevin J. Liu, Xuechun Wang, Vinod K. Sangwan, Han Wang, Mark C. Hersam
Summary: This study presents a reconfigurable mixed-kernel transistor based on dual-gated van der Waals heterojunctions for low-power off-grid medical data classification and diagnosis applications. The experimental results show that this transistor can generate fully tunable Gaussian and sigmoid functions for arrhythmia detection from electrocardiogram signals with high classification accuracy. Additionally, the reconfigurable nature of this transistor allows for personalized detection. Compared to conventional complementary metal-oxide-semiconductor circuits, a single mixed-kernel heterojunction transistor provides a low-power approach for support vector machine classification applications.
NATURE ELECTRONICS
(2023)
