Article
Chemistry, Physical
Stavros Katsiaounis, Nikos Delikoukos, Antonios Michail, John Parthenios, Konstantinos Papagelis
Summary: We studied the effects of electron-phonon and phonon-phonon interactions on the linewidth of the G phonon in both unintentionally and intentionally doped polycrystalline chemical vapor deposited (CVD) graphene samples using conventional and time-resolved Raman spectroscopy. We found that the lifetime of the G phonon decreased approximately by 14% with increasing doping, contrary to the anticipated reduction in G phonon linewidth due to a decrement in electron-phonon contribution from first principles calculations. The CVD samples exhibited a decrease of approximately 30% in the electron-phonon coupling constant compared to exfoliated graphene samples. Additionally, the contribution of phonon-defect scattering to the G band linewidth was significant in CVD graphene samples due to their lower crystal quality compared to exfoliated graphene.
Article
Energy & Fuels
Nilesh Mohan Khalse, Mahuya De
Summary: This study investigated the effect of nitrogen doping on the adsorptive removal of sulfur compounds from model fuel. Nitrogen doping improved the surface area and pore volume of templated carbon, thereby enhancing the adsorption capacity of sulfur compounds. The adsorption-regeneration cycles showed that the removal efficiency was only lowered by 4-10% after five cycles.
Article
Chemistry, Physical
Marios Zacharias, Pantelis C. Kelires
Summary: Through calculations and a special method, we demonstrate the quantum confinement scaling law of phonon-induced gap renormalization of graphene quantum dots, showing strong quantum confinement effects in GQDs within the sub-10 nm range and laying the foundation for designing temperature-dependent electronic structures.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2021)
Article
Nanoscience & Nanotechnology
Robin Singla, Ambika Shankar Shukla, Anil Kottantharayil
Summary: A method to dope monolayer CVD graphene with nitrogen and induce ferromagnetism was demonstrated, showing a coercivity of 222 Oe at low temperatures. Changes in the angle of the applied magnetic field affected the anisotropic magnetoresistance effect in the doped graphene devices, with varying AMR values at different temperatures. The introduction of magnetism in CVD graphene after nitrogen doping was confirmed through magnetic force microscopy and electron spin resonance spectroscopy, suggesting potential applications in spintronics.
Article
Chemistry, Multidisciplinary
Rui Tang, Alex Aziz, Wei Yu, Zheng-Ze Pan, Ginga Nishikawa, Takeharu Yoshii, Keita Nomura, Erin E. Taylor, Nicholas P. Stadie, Kazutoshi Inoue, Motoko Kotani, Takashi Kyotani, Hirotomo Nishihara
Summary: Porous carbons are important electrode materials for supercapacitors. This study investigates the impact of heteroatom functionalities on total capacitance in 3D mesoporous graphenes. It is found that nitrogen functionalities significantly enhance total capacitance.
Article
Energy & Fuels
Hailong Shen, Xiaochun Wei, Zhenqi Cen, Dan Lu, Man Cai, Haifu Huang, Zhiqiang Lan, Xianqing Liang, Wenzheng Zhou
Summary: This study demonstrates the successful synthesis of nitrogen-doped graphene through UV light radiation and thermal decomposition of ammonium bicarbonate. The nitrogen-doped graphene exhibits high specific capacitance, good rate performance, and cycle stability in the form of spherical nanoparticles.
JOURNAL OF ENERGY STORAGE
(2022)
Article
Materials Science, Multidisciplinary
Habib Rostami
Summary: In this work, a diagrammatic formalism for nonlinear Raman force is presented and implemented to shear phonon dynamics in bilayer graphene. A controllable splitting of double degenerate shear phonon modes due to light-induced phonon mixing and renormalization is predicted. Furthermore, a light-induced shear phonon softening that facilitates structural instability at a critical field amplitude is observed. The phonon splitting and instability strongly depend on various factors such as laser intensity, frequency, chemical potential, and temperature.
Article
Engineering, Chemical
Jianping Yuan, Pan Yang, Liying Long, Haike Yang, Yiqun Chen, Zizheng Liu, Qing Shao, Feng Wu, Pengchao Xie, Jun Ma
Summary: In this study, a nitrogen-doped reduced graphene oxide material was synthesized and used as a catalyst for the removal of As(III) in water. The pH and dissolved oxygen of the solution were found to be the key factors affecting the removal efficiency. Density functional theory calculations showed that sulfite activation occurred more likely on C atoms adjacent to the N dopant, and the generated hydroxyl radical played a vital role in As(III) oxidation. The conversion of pyridinic nitrogen to pyrrolic nitrogen was responsible for the poor long-term stability of the catalyst.
SEPARATION AND PURIFICATION TECHNOLOGY
(2023)
Article
Polymer Science
Hekun Ding, Qiongyue Zhang, Xingjin Yang, Qingge Feng, Dongbo Wang, Zheng Liu
Summary: By synthesizing the TAP-BPC/CN composite with desirable conductivity through mixing 2,4,6-triaminopyrimidine (TAP) doped melamine and biomass porous carbon (BPC), a new strategy for efficient photocatalysts with high absorption and photocatalysis in the antibiotic wastewater treatment is provided.
JOURNAL OF APPLIED POLYMER SCIENCE
(2023)
Article
Chemistry, Multidisciplinary
Xiao Guo, Yongsong Wang, Siwen You, Dingbang Yang, Guiping Jia, Fei Song, Weidong Dou, Han Huang
Summary: Graphene has high carrier mobility and concentration, as well as other remarkable properties. The thermal behaviors of phonon modes play important roles in the application of optical and electronic devices. This study conducted temperature-dependent Raman scattering measurements on graphene with various number of layers on different substrates and found that the substrate effect has a significant impact on the graphene phonon temperature dependence.
Article
Materials Science, Multidisciplinary
Roque Sanchez-Salas, Emilio Munoz-Sandoval, Morinobu Endo, Aaron Morelos-Gomez, Florentino Lopez-Urias
Summary: Graphene oxide reduction and doping can be achieved through mechanochemical method with urea and thiourea molecules, which can be covalently linked to graphene sheets. The connection method between urea/thiourea molecules and graphene sheets affects the energy levels and doping effects of the material.
ADVANCED ENGINEERING MATERIALS
(2021)
Article
Chemistry, Physical
Aya Hamed, Amr Hessein, Ahmed Abd El-Moneim
Summary: A novel fabrication approach using a CO2 Laser system to achieve real-time doping, reduction, and patterning of graphene oxide-based films has been proposed in this study. Different types of planar supercapacitors were readily fabricated with high nitrogen and sulfur content in the graphene framework, leading to excellent electrochemical performance. The versatility of the proposed approach was demonstrated by achieving higher energy density, power density, and retention rate in flexible graphene-based electrochemical storage devices.
APPLIED SURFACE SCIENCE
(2021)
Article
Thermodynamics
Ekaterina A. Arkhipova, Anton S. Ivanov, Natalia E. Strokova, Konstantin Maslakov, Sergei A. Chernyak, Serguei Savilov
Summary: Nitrogen-doped graphene nanoflakes with variable N-doping levels were prepared by chemical vapor deposition and characterized for their structure and combustion heats. The combustion heats showed a bell-shaped dependence on nitrogen content and the contributions of different factors to the combustion heat were discussed.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2022)
Article
Chemistry, Physical
Gengyuan Liang, Suli Xing, Linfeng Yu, Guangzhao Qin, Bowen Lei, Yonglyu He, Jun Tang, Su Ju, Shuxin Bai, Jianwei Zhang
Summary: Graphene's zero-band gap limitation can be overcome by nitrogen doping, which allows for adjustment of its band structure. A fast process for preparing nitrogen doped graphene (NG) films has been developed, with the ability to effectively control the type and content of doped nitrogen atoms. The NG films show promising thermoelectric properties and have potential for functional applications.
APPLIED SURFACE SCIENCE
(2022)
Article
Chemistry, Multidisciplinary
G. Kanimozhi, Naresh Nibagani, Durga S. Nair, Harish Kumar, N. Satyanarayana
Summary: Alpha-Fe2O3 nanofacets were synthesized using the microwave-assisted solvothermal method and wrapped with nitrogen-doped reduced Graphene oxide. The resulting material exhibited high specific capacity and showed promise for use in electrochemical devices.
JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS
(2022)
Article
Physics, Multidisciplinary
Hongchao Xie, Xiangpeng Luo, Gaihua Ye, Zhipeng Ye, Haiwen Ge, Suk Hyun Sung, Emily Rennich, Shaohua Yan, Yang Fu, Shangjie Tian, Hechang Lei, Robert Hovden, Kai Sun, Rui He, Liuyan Zhao
Summary: This study demonstrates successful twist engineering of 2D magnetism by fabricating twisted double bilayers of a 2D magnet, chromium triiodide (CrI3). It identifies a new magnetic ground state that differs from natural two-layer and four-layer CrI3 structures, and shows that the emergent magnetism for small and large twist angles resemble different configurations, while an intermediate twist angle introduces net magnetization due to spin frustrations.
Article
Multidisciplinary Sciences
Suk Hyun Sung, Noah Schnitzer, Steve Novakov, Ismail El Baggari, Xiangpeng Luo, Jiseok Gim, Nguyen M. Vu, Zidong Li, Todd H. Brintlinger, Yu Liu, Wenjian Lu, Yuping Sun, Parag B. Deotare, Kai Sun, Liuyan Zhao, Lena F. Kourkoutis, John T. Heron, Robert Hovden
Summary: The study demonstrates a route to realizing fragile 2D quantum states through endotaxial polytype engineering of van der Waals materials, isolating 2D charge density waves and restoring mirror symmetries via interlayer CDW twinning. The newly reported twinned-commensurate charge density wave (tC-CDW) shows a single metal-insulator phase transition at around 350 K and can be mapped using in-situ transmission electron microscopy and nanobeam diffraction. This work introduces a novel approach to access latent 2D ground states distinct from conventional methods.
NATURE COMMUNICATIONS
(2022)
Article
Physics, Multidisciplinary
Alberto de la Torre, Kyle L. Seyler, Michael Buchhold, Yuval Baum, Gufeng Zhang, Nicholas J. Laurita, John W. Harter, Liuyan Zhao, Isabelle Phinney, Xiang Chen, Stephen D. Wilson, Gang Cao, Richard D. Averitt, Gil Refael, David Hsieh
Summary: The study investigates the ultrafast non-equilibrium dynamics of the antiferromagnetic Mott insulator Sr2IrO4 using second harmonic optical polarimetry and coherent magnon spectroscopy. The results reveal a far-from-equilibrium critical regime where static and dynamic behavior decouple.
COMMUNICATIONS PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Kai Huang, Ding-Fu Shao, Evgeny Y. Tsymbal
Summary: In this study, we demonstrate the electrical control of DMI and magnetic skyrmions in a Fe3GeTe2 monolayer through the ferroelectric polarization of an adjacent 2D vdW ferroelectric In2Se3. The results show that the magnitude and sign of DMI can be controlled by ferroelectric polarization reversal, leading to the creation and annihilation of skyrmions.
Article
Physics, Multidisciplinary
Jianting Dong, Xinlu Li, Gautam Gurung, Meng Zhu, Peina Zhang, Fanxing Zheng, Evgeny Y. Tsymbal, Jia Zhang
Summary: Antiferromagnetic spintronics is a subfield of spintronics that takes advantage of antiferromagnets producing no stray fields and exhibiting ultrafast magnetization dynamics. This study demonstrates the potential of utilizing noncollinear antiferromagnetic metals to achieve high tunneling magnetoresistance (TMR) effect, which can be used to detect the Néel vector and produce multiple nonvolatile resistance states.
PHYSICAL REVIEW LETTERS
(2022)
Article
Nanoscience & Nanotechnology
S. Ryu, H. Zhou, T. R. Paudel, N. Campbell, J. Podkaminer, C. W. Bark, T. Hernandez, D. D. Fong, Y. Zhang, L. Xie, X. Q. Pan, E. Y. Tsymbal, M. S. Rzchowski, C. B. Eom
Summary: Atomic flat (111) interfaces between insulating perovskite oxides provide a landscape for new electronic phenomena, such as graphene-like coordination between interfacial metallic ion layer pairs leading to topologically protected states. In this study, epitaxial heterostructures of (111)-oriented LaAlO3/SrTiO3 (LAO/STO) were investigated, and it was found that the LAO overlayer eliminates the structural reconstruction of the STO (111) surface through an electronic reconstruction, determining the properties of the resulting two-dimensional conducting gas.
Article
Engineering, Electrical & Electronic
Arnab Bose, Nathaniel J. Schreiber, Rakshit Jain, Ding-Fu Shao, Hari P. Nair, Jiaxin Sun, Xiyue S. Zhang, David A. Muller, Evgeny Y. Tsymbal, Darrell G. Schlom, Daniel C. Ralph
Summary: Symmetry plays a central role in determining the polarization of spin currents induced by electric fields. In this study, an out-of-plane damping-like torque is shown to be generated in RuO2/permalloy devices when the Neel vector of the collinear antiferromagnet RuO2 is canted relative to the sample plane. By measuring characteristic changes in the electric-field-induced torque vector, it is found that RuO2 generates a spin current with a well-defined tilted spin orientation parallel to the Neel vector. This antiferromagnetic spin Hall effect has distinct symmetries from other mechanisms of spin-current generation reported in antiferromagnetic and ferromagnetic materials.
NATURE ELECTRONICS
(2022)
Article
Nanoscience & Nanotechnology
Alexey Lipatov, Pradeep Chaudhary, Zhao Guan, Haidong Lu, Gang Li, Olivier Cregut, Kokou Dodzi Dorkenoo, Roger Proksch, Salia Cherifi-Hertel, Ding-Fu Shao, Evgeny Y. Tsymbal, Jorge Iniguez, Alexander Sinitskii, Alexei Gruverman
Summary: Recent theoretical predictions have suggested that two-dimensional van der Waals materials may exhibit ferroelectric properties, opening up exciting possibilities for scalable low-power electronic devices. Experimental evidence of polarization response has been observed in narrow-band semiconductors and semimetals known as transition metal chalcogenides (TMCs), with molybdenum disulfide (MoS2) being one of the most promising 2D electronic materials. However, despite theoretical predictions, no ferroelectricity has been experimentally detected in MoS2, although its emergence could enhance its potential for electronics applications.
NPJ 2D MATERIALS AND APPLICATIONS
(2022)
Article
Multidisciplinary Sciences
Zhongran Liu, Han Wang, Ming Li, Lingling Tao, Tula R. Paudel, Hongyang Yu, Yuxuan Wang, Siyuan Hong, Meng Zhang, Zhaohui Ren, Yanwu Xie, Evgeny Y. Tsymbal, Jingsheng Chen, Ze Zhang, He Tian
Summary: Domain-wall nanoelectronics is a new paradigm for non-volatile memory and logic technologies, where domain walls serve as an active element. Charged domain walls in ferroelectric structures have unique electronic and transport properties, which are useful for various nanoelectronics applications. In this study, a strategy for controllable creation and manipulation of charged domain walls in BiFeO3 ferroelectric films is reported, and their functionality as a memristor a few unit cells thick is demonstrated.
Article
Chemistry, Physical
Bowen Yang, Yin Min Goh, Suk Hyun Sung, Gaihua Ye, Sananda Biswas, David A. S. Kaib, Ramesh Dhakal, Shaohua Yan, Chenghe Li, Shengwei Jiang, Fangchu Chen, Hechang Lei, Rui He, Roser Valenti, Stephen M. Winter, Robert Hovden, Adam W. Tsen
Summary: The authors investigate the magnetic anisotropy in monolayer RuCl3 and observe a transition from easy-plane to easy-axis due to in-plane distortions of Cl atoms. This finding is important for realizing a quantum spin liquid. The study provides insights into the possibility of exploring Kitaev physics in a true two-dimensional limit.
Article
Chemistry, Physical
Zifang Liu, Pengfei Hou, Lizhong Sun, Evgeny Y. Tsymbal, Jie Jiang, Qiong Yang
Summary: In this work, a two-dimensional van der Waals heterostructure composed of an alpha-In2Se3 ferroelectric and a hexagonal IV-VI semiconductor is designed, and an in-plane ferroelectric tunnel junction based on these heterostructures is proposed. First-principles calculations show that the electronic band structure of the designed heterostructures can be switched between insulating and metallic states by ferroelectric polarization. It is demonstrated that the in-plane ferroelectric tunnel junction exhibits two distinct transport regimes, tunneling and metallic, for OFF and ON states, respectively, resulting in a giant tunneling electroresistance effect with the OFF/ON resistance ratio exceeding 1 x 10(4). The results provide a promising approach for high-density ferroelectric memory based on 2D ferroelectric/semiconductor heterostructures.
NPJ COMPUTATIONAL MATERIALS
(2023)
Editorial Material
Chemistry, Physical
Youngjun Ahn, Liuyan Zhao
Article
Chemistry, Physical
D. C. Mahendra, Ding-Fu Shao, Vincent D. -H. Hou, Arturas Vailionis, P. Quarterman, Ali Habiboglu, M. B. Venuti, Fen Xue, Yen-Lin Huang, Chien-Min Lee, Masashi Miura, Brian Kirby, Chong Bi, Xiang Li, Yong Deng, Shy-Jay Lin, Wilman Tsai, Serena Eley, Wei-Gang Wang, Julie A. Borchers, Evgeny Y. Tsymbal, Shan X. Wang
Summary: By utilizing unconventional spins generated in a MnPd3 thin film grown on an oxidized silicon substrate, the authors observed both conventional spin-orbit torques and unconventional out-of-plane and in-plane anti-damping-like torques in MnPd3/CoFeB heterostructures, enabling complete field-free switching of perpendicular cobalt. These unconventional torques are attributed to the low symmetry of the (114)-oriented MnPd3 films. The results provide a path towards practical spin channels in ultrafast magnetic memory and logic devices.
Article
Physics, Multidisciplinary
Haoying Sun, Jiahui Gu, Yongqiang Li, Tula R. Paudel, Di Liu, Jierong Wang, Yipeng Zang, Chengyi Gu, Jiangfeng Yang, Wenjie Sun, Zhengbin Gu, Evgeny Y. Tsymbal, Junming Liu, Houbing Huang, Di Wu, Yuefeng Nie
Summary: By applying uniaxial strain, we achieved pure in-plane polarized ferroelectricity in ultrathin SrTiO3 membranes, which allows for the investigation of ferroelectric size effects without the interference of the depolarization field. Our study reveals that the stability of ferroelectricity is influenced by the thickness-dependent dipole-dipole interactions within the transverse Ising model.
PHYSICAL REVIEW LETTERS
(2023)
Article
Multidisciplinary Sciences
Shu Shi, Haolong Xi, Tengfei Cao, Weinan Lin, Zhongran Liu, Jiangzhen Niu, Da Lan, Chenghang Zhou, Jing Cao, Hanxin Su, Tieyang Zhao, Ping Yang, Yao Zhu, Xiaobing Yan, Evgeny Y. Tsymbal, He Tian, Jingsheng Chen
Summary: The authors demonstrate the stabilization of the metastable orthorhombic phase in Hf0.5 Zr0.5O2 films through interface engineering and hole doping.
NATURE COMMUNICATIONS
(2023)
