The Experts below are selected from a list of 30489 Experts worldwide ranked by ideXlab platform
Yoshiyuki Kawazoe - One of the best experts on this subject based on the ideXlab platform.
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Body-Centered Tetragonal C16 : A Novel Topological Node-Line Semimetallic Carbon Composed of Tetrarings.
Small (Weinheim an der Bergstrasse Germany), 2017Co-Authors: Yong Cheng, Bin Wen, Xing Feng, Xiaoting Cao, Qian Wang, Yoshiyuki Kawazoe, Puru JenaAbstract:The present work not only predicts the existence of 3D topological semimetallic carbon allotropes composed of tetrarings, but also provides a likely crystalLine structure for the unknown phase produced in the detonation soot.
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body centered orthorhombic c 16 a novel topological Node Line semimetal
Physical Review Letters, 2016Co-Authors: Jiantao Wang, Yoshiyuki Kawazoe, Hongming Weng, Zhong Fang, Simin Nie, Changfeng ChenAbstract:We identify by ab initio calculations a novel topological semimetal carbon phase in all-sp^{2} bonding networks with a 16-atom body-centered orthorhombic unit cell, termed bco-C_{16}. Total-energy calculations show that bco-C_{16} is comparable to solid fcc-C_{60} in energetic stability, and phonon and molecular dynamics simulations confirm its dynamical stability. This all-sp^{2} carbon allotrope can be regarded as a three-dimensional modification of graphite, and its simulated x-ray diffraction (XRD) pattern matches well a previously unexplained diffraction peak in measured XRD spectra of detonation and chimney soot, indicating its presence in the specimen. Electronic band structure calculations reveal that bco-C_{16} is a topological Node-Line semimetal with a single nodal ring. These findings establish a novel carbon phase with intriguing structural and electronic properties of fundamental significance and practical interest.
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topological Node Line semimetal in three dimensional graphene networks
Physical Review B, 2015Co-Authors: Hongming Weng, Yoshiyuki Kawazoe, Zhong Fang, Xi Dai, Yunye LiangAbstract:Graphene, a two-dimensional (2D) carbon sheet, acquires many of its amazing properties from the Dirac point nature of its electronic structures with negligible spin-orbit coupling. Extending to 3D space, graphene networks with negative curvature, called Mackay-Terrones crystals (MTCs), have been proposed and experimentally explored, yet their topological properties have yet to be discovered. Based on the first-principle calculations, we report an all-carbon MTC with topologically nontrivial electronic states by exhibiting Node Lines in bulk. When the Node Lines are projected onto surfaces to form circles, ``drumhead''-like flat surface bands nestled inside of the circles are formed. The bulk Node Line can evolve into a 3D Dirac point in the absence of inversion symmetry, the existence of which has been shown to be plausible in recent experiments.
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topological Node Line semimetal in three dimensional graphene networks
Bulletin of the American Physical Society, 2015Co-Authors: Hongming Weng, Yoshiyuki Kawazoe, Zhong Fang, Xi Dai, Yunye LiangAbstract:Graphene, a two dimensional (2D) carbon sheet, acquires many of its amazing properties from the Dirac point nature of its electronic structures with negligible spin-orbit coupling. Extending to 3D space, graphene networks with negative curvature, called Mackay-Terrones crystals (MTC), have been proposed and experimentally explored, yet their topological properties remain to be discovered. Based on the rst-principle calculations, we report an all-carbon MTC with topologically non-trivial electronic states by exhibiting Node-Lines in bulk. When the Node-Lines are projected on to surfaces to form circles, \drumhead" like at surface bands nestled inside of the circles are formed. The bulk Node-Line can evolve into 3D Dirac point in the absence of inversion symmetry, which has shown its plausible existence in recent experiments.
Hongming Weng - One of the best experts on this subject based on the ideXlab platform.
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multi loop Node Line states in ternary mgsrsi type crystals
npj Computational Materials, 2019Co-Authors: Jinling Lian, Qifeng Liang, Jian Zhou, Hongming WengAbstract:Node Line band-touchings protected by mirror symmetry (named as m-NLs), the product of inversion and time reversal symmetry S = PT (named as s-NLs), or nonsymmorphic symmetry are nontrivial topological objects of topological semimetals in the Brillouin Zone. In this work, we screened a family of MgSrSi-type crystals using first principles calculations, and discovered that more than 70 members are Node-Line semimetals. A new type of multi-loop structure was found in AsRhTi that a s-NL touches robustly with a m-NL at some “nexus point”, and in the meanwhile a second m-NL crosses with the s-NL to form a Hopf-link. Unlike the previously proposed Hopf-link formed by two s-NLs or two m-NLs, a Hopf-link formed by a s-NL and a m-NL requires a minimal three-band model to characterize its essential electronic structure. The associated topological surface states on different surfaces of AsRhTi crystal were also obtained. Even more complicated and exotic multi-loop structure of NLs were predicted in AsFeNb and PNiNb. Our work may shed light on search for exotic multi-loop Node-Line semimetals in real materials.
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orthorhombic carbon oc24 a novel topological nodal Line semimetal
Carbon, 2018Co-Authors: Jia Chen, Hongming Weng, Simin Nie, Hiroshi Mizuseki, Jiantao WangAbstract:Abstract We identify by ab initio calculations a stable three-dimensional carbon allotrope that constructed by inserting benzene rings into the carbon-carbon bonds in a previously reported oC8 carbon. This new carbon phase has a 24-atom orthorhombic unit cell in C m m m ( D 2 H 19 ) symmetry and thus termed oC24. Phonon mode analysis confirms its dynamical stable. Total-energy calculations show that it is energetically stable comparable with (5,5) carbon nanotube. Detailed electronic band calculations reveal that oC24 is a topological Node-Line semimetal with two mirror-inversion symmetric nodal Lines that go through the whole Brillouin zone in bulk and a projected surface flat band around the Fermi level. The present results establish a new type of carbon phases and offer insights into their outstanding structural and electronic properties.
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topological Node Line semimetal in compressed black phosphorus
Physical Review B, 2016Co-Authors: Jianzhou Zhao, Hongming Weng, Zhong FangAbstract:Based on first-principles calculations and tight-binding model analysis, we propose that black phosphorus (BP) can host a three-dimensional topological Node-Line semimetal state under pressure when spin-orbit coupling (SOC) is ignored. A closed topological Node Line exists in the first Brillouin zone (BZ) near the Fermi energy, which is protected by the coexistence of time-reversal and spatial inversion symmetry with band inversion driven by pressure. Drumheadlike surface states have been obtained on the beard (100) surface. Due to the weak intrinsic SOC of a phosphorus atom, a band gap less than 10 meV is opened along the Node Line in the presence of SOC, and the surface states are almost unaffected by SOC.
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topological semimetals predicted from first principles calculations
Journal of Physics: Condensed Matter, 2016Co-Authors: Hongming Weng, Xi Dai, Zhong FangAbstract:We have given a summary on our theoretical predictions of three kinds of topological semimetals (TSMs), namely, Dirac semimetal (DSM), Weyl semimetal (WSM) and Node-Line semimetal (NLSM). TSMs are new states of quantum matter, which are different from topological insulators. They are characterized by the topological stability of the Fermi surface, whether it encloses band crossing points, i.e. Dirac cone-like energy Nodes, or not. They are distinguished from each other by the degeneracy and momentum space distribution of the nodal points. To realize these intriguing topological quantum states is quite challenging and crucial to both fundamental science and future application. Na3Bi and Cd3As2 were theoretically predicted to be DSM in 2012 and 2013 respectively. Their experimental verification in 2014 have ignited intensive studies on TSMs. The subsequent theoretical prediction of a nonmagnetic WSM in the TaAs family stimulated a second wave and many experimental works were released out in 2015. In 2014, a kind of three dimensional crystal of carbon was proposed to be an NLSM due to negligible spin-orbit coupling and coexistence of time-reversal and inversion symmetry. Though the final experimental confirmation of NLSM is still missing, there have been several theoretical proposals, including Cu3PdN from us. In the final part, we have summarized the whole family of TSMs and their relationships.
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body centered orthorhombic c 16 a novel topological Node Line semimetal
Physical Review Letters, 2016Co-Authors: Jiantao Wang, Yoshiyuki Kawazoe, Hongming Weng, Zhong Fang, Simin Nie, Changfeng ChenAbstract:We identify by ab initio calculations a novel topological semimetal carbon phase in all-sp^{2} bonding networks with a 16-atom body-centered orthorhombic unit cell, termed bco-C_{16}. Total-energy calculations show that bco-C_{16} is comparable to solid fcc-C_{60} in energetic stability, and phonon and molecular dynamics simulations confirm its dynamical stability. This all-sp^{2} carbon allotrope can be regarded as a three-dimensional modification of graphite, and its simulated x-ray diffraction (XRD) pattern matches well a previously unexplained diffraction peak in measured XRD spectra of detonation and chimney soot, indicating its presence in the specimen. Electronic band structure calculations reveal that bco-C_{16} is a topological Node-Line semimetal with a single nodal ring. These findings establish a novel carbon phase with intriguing structural and electronic properties of fundamental significance and practical interest.
Zhong Fang - One of the best experts on this subject based on the ideXlab platform.
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topological Node Line semimetal in compressed black phosphorus
Physical Review B, 2016Co-Authors: Jianzhou Zhao, Hongming Weng, Zhong FangAbstract:Based on first-principles calculations and tight-binding model analysis, we propose that black phosphorus (BP) can host a three-dimensional topological Node-Line semimetal state under pressure when spin-orbit coupling (SOC) is ignored. A closed topological Node Line exists in the first Brillouin zone (BZ) near the Fermi energy, which is protected by the coexistence of time-reversal and spatial inversion symmetry with band inversion driven by pressure. Drumheadlike surface states have been obtained on the beard (100) surface. Due to the weak intrinsic SOC of a phosphorus atom, a band gap less than 10 meV is opened along the Node Line in the presence of SOC, and the surface states are almost unaffected by SOC.
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topological semimetals predicted from first principles calculations
Journal of Physics: Condensed Matter, 2016Co-Authors: Hongming Weng, Xi Dai, Zhong FangAbstract:We have given a summary on our theoretical predictions of three kinds of topological semimetals (TSMs), namely, Dirac semimetal (DSM), Weyl semimetal (WSM) and Node-Line semimetal (NLSM). TSMs are new states of quantum matter, which are different from topological insulators. They are characterized by the topological stability of the Fermi surface, whether it encloses band crossing points, i.e. Dirac cone-like energy Nodes, or not. They are distinguished from each other by the degeneracy and momentum space distribution of the nodal points. To realize these intriguing topological quantum states is quite challenging and crucial to both fundamental science and future application. Na3Bi and Cd3As2 were theoretically predicted to be DSM in 2012 and 2013 respectively. Their experimental verification in 2014 have ignited intensive studies on TSMs. The subsequent theoretical prediction of a nonmagnetic WSM in the TaAs family stimulated a second wave and many experimental works were released out in 2015. In 2014, a kind of three dimensional crystal of carbon was proposed to be an NLSM due to negligible spin-orbit coupling and coexistence of time-reversal and inversion symmetry. Though the final experimental confirmation of NLSM is still missing, there have been several theoretical proposals, including Cu3PdN from us. In the final part, we have summarized the whole family of TSMs and their relationships.
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body centered orthorhombic c 16 a novel topological Node Line semimetal
Physical Review Letters, 2016Co-Authors: Jiantao Wang, Yoshiyuki Kawazoe, Hongming Weng, Zhong Fang, Simin Nie, Changfeng ChenAbstract:We identify by ab initio calculations a novel topological semimetal carbon phase in all-sp^{2} bonding networks with a 16-atom body-centered orthorhombic unit cell, termed bco-C_{16}. Total-energy calculations show that bco-C_{16} is comparable to solid fcc-C_{60} in energetic stability, and phonon and molecular dynamics simulations confirm its dynamical stability. This all-sp^{2} carbon allotrope can be regarded as a three-dimensional modification of graphite, and its simulated x-ray diffraction (XRD) pattern matches well a previously unexplained diffraction peak in measured XRD spectra of detonation and chimney soot, indicating its presence in the specimen. Electronic band structure calculations reveal that bco-C_{16} is a topological Node-Line semimetal with a single nodal ring. These findings establish a novel carbon phase with intriguing structural and electronic properties of fundamental significance and practical interest.
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topological semimetals predicted from first principles calculations
arXiv: Materials Science, 2016Co-Authors: Hongming Weng, Xi Dai, Zhong FangAbstract:We have given a summary on our theoretical predictions of three kinds of topological semimetals (TSMs), namely, Dirac semimetal (DSM), Weyl semimetal (WSM) and Node-Line Semimetal (NLSM). TSMs are new states of quantum matters, which are different with topological insulators. They are characterized by the topological stability of Fermi surface, whether it encloses band crossing point, i.e., Dirac cone like energy Node, or not. They are distinguished from each other by the degeneracy and momentum space distribution of the nodal points. To realize these intriguing topological quantum states is quite challenging and crucial to both fundamental science and future application. In 2012 and 2013, Na$_3$Bi and Cd$_3$As$_2$ were theoretically predicted to be DSM, respectively. Their experimental verifications in 2014 have ignited the hot and intensive studies on TSMs. The following theoretical prediction of nonmagnetic WSM in TaAs family stimulated a second wave and many experimental works have come out in this year. In 2014, a kind of three dimensional crystal of carbon has been proposed to be NLSM due to negligible spin-orbit coupling and coexistence of time-reversal and inversion symmetry. Though the final experimental confirmation of NLSM is still missing, there have been several theoretical proposals, including Cu$_3$PdN from us. In the final part, we have summarized the whole family of TSMs and their relationship.
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topological Node Line semimetal and dirac semimetal state in antiperovskite cu 3 pdn
Physical Review Letters, 2015Co-Authors: Hongming Weng, Zhong Fang, Xi DaiAbstract:Based on first-principles calculation and effective model analysis, we propose that the cubic antiperovskite material Cu3PdN can host a three-dimensional (3D) topological Node-Line semimetal state when spin-orbit coupling (SOC) is ignored, which is protected by the coexistence of time-reversal and inversion symmetry. There are three Node-Line circles in total due to the cubic symmetry. Drumheadlike surface flat bands are also derived. When SOC is included, each Node Line evolves into a pair of stable 3D Dirac points as protected by C4 crystal symmetry. This is remarkably distinguished from the Dirac semimetals known so far, such as Na3Bi and Cd3As2, both having only one pair of Dirac points. Once C4 symmetry is broken, the Dirac points are gapped and the system becomes a strong topological insulator with (1;111) Z2 indices.
Xi Dai - One of the best experts on this subject based on the ideXlab platform.
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topological semimetals predicted from first principles calculations
Journal of Physics: Condensed Matter, 2016Co-Authors: Hongming Weng, Xi Dai, Zhong FangAbstract:We have given a summary on our theoretical predictions of three kinds of topological semimetals (TSMs), namely, Dirac semimetal (DSM), Weyl semimetal (WSM) and Node-Line semimetal (NLSM). TSMs are new states of quantum matter, which are different from topological insulators. They are characterized by the topological stability of the Fermi surface, whether it encloses band crossing points, i.e. Dirac cone-like energy Nodes, or not. They are distinguished from each other by the degeneracy and momentum space distribution of the nodal points. To realize these intriguing topological quantum states is quite challenging and crucial to both fundamental science and future application. Na3Bi and Cd3As2 were theoretically predicted to be DSM in 2012 and 2013 respectively. Their experimental verification in 2014 have ignited intensive studies on TSMs. The subsequent theoretical prediction of a nonmagnetic WSM in the TaAs family stimulated a second wave and many experimental works were released out in 2015. In 2014, a kind of three dimensional crystal of carbon was proposed to be an NLSM due to negligible spin-orbit coupling and coexistence of time-reversal and inversion symmetry. Though the final experimental confirmation of NLSM is still missing, there have been several theoretical proposals, including Cu3PdN from us. In the final part, we have summarized the whole family of TSMs and their relationships.
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topological semimetals predicted from first principles calculations
arXiv: Materials Science, 2016Co-Authors: Hongming Weng, Xi Dai, Zhong FangAbstract:We have given a summary on our theoretical predictions of three kinds of topological semimetals (TSMs), namely, Dirac semimetal (DSM), Weyl semimetal (WSM) and Node-Line Semimetal (NLSM). TSMs are new states of quantum matters, which are different with topological insulators. They are characterized by the topological stability of Fermi surface, whether it encloses band crossing point, i.e., Dirac cone like energy Node, or not. They are distinguished from each other by the degeneracy and momentum space distribution of the nodal points. To realize these intriguing topological quantum states is quite challenging and crucial to both fundamental science and future application. In 2012 and 2013, Na$_3$Bi and Cd$_3$As$_2$ were theoretically predicted to be DSM, respectively. Their experimental verifications in 2014 have ignited the hot and intensive studies on TSMs. The following theoretical prediction of nonmagnetic WSM in TaAs family stimulated a second wave and many experimental works have come out in this year. In 2014, a kind of three dimensional crystal of carbon has been proposed to be NLSM due to negligible spin-orbit coupling and coexistence of time-reversal and inversion symmetry. Though the final experimental confirmation of NLSM is still missing, there have been several theoretical proposals, including Cu$_3$PdN from us. In the final part, we have summarized the whole family of TSMs and their relationship.
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topological Node Line semimetal and dirac semimetal state in antiperovskite cu 3 pdn
Physical Review Letters, 2015Co-Authors: Hongming Weng, Zhong Fang, Xi DaiAbstract:Based on first-principles calculation and effective model analysis, we propose that the cubic antiperovskite material Cu3PdN can host a three-dimensional (3D) topological Node-Line semimetal state when spin-orbit coupling (SOC) is ignored, which is protected by the coexistence of time-reversal and inversion symmetry. There are three Node-Line circles in total due to the cubic symmetry. Drumheadlike surface flat bands are also derived. When SOC is included, each Node Line evolves into a pair of stable 3D Dirac points as protected by C4 crystal symmetry. This is remarkably distinguished from the Dirac semimetals known so far, such as Na3Bi and Cd3As2, both having only one pair of Dirac points. Once C4 symmetry is broken, the Dirac points are gapped and the system becomes a strong topological insulator with (1;111) Z2 indices.
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topological Node Line semimetal in three dimensional graphene networks
Physical Review B, 2015Co-Authors: Hongming Weng, Yoshiyuki Kawazoe, Zhong Fang, Xi Dai, Yunye LiangAbstract:Graphene, a two-dimensional (2D) carbon sheet, acquires many of its amazing properties from the Dirac point nature of its electronic structures with negligible spin-orbit coupling. Extending to 3D space, graphene networks with negative curvature, called Mackay-Terrones crystals (MTCs), have been proposed and experimentally explored, yet their topological properties have yet to be discovered. Based on the first-principle calculations, we report an all-carbon MTC with topologically nontrivial electronic states by exhibiting Node Lines in bulk. When the Node Lines are projected onto surfaces to form circles, ``drumhead''-like flat surface bands nestled inside of the circles are formed. The bulk Node Line can evolve into a 3D Dirac point in the absence of inversion symmetry, the existence of which has been shown to be plausible in recent experiments.
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topological Node Line semimetal in three dimensional graphene networks
Bulletin of the American Physical Society, 2015Co-Authors: Hongming Weng, Yoshiyuki Kawazoe, Zhong Fang, Xi Dai, Yunye LiangAbstract:Graphene, a two dimensional (2D) carbon sheet, acquires many of its amazing properties from the Dirac point nature of its electronic structures with negligible spin-orbit coupling. Extending to 3D space, graphene networks with negative curvature, called Mackay-Terrones crystals (MTC), have been proposed and experimentally explored, yet their topological properties remain to be discovered. Based on the rst-principle calculations, we report an all-carbon MTC with topologically non-trivial electronic states by exhibiting Node-Lines in bulk. When the Node-Lines are projected on to surfaces to form circles, \drumhead" like at surface bands nestled inside of the circles are formed. The bulk Node-Line can evolve into 3D Dirac point in the absence of inversion symmetry, which has shown its plausible existence in recent experiments.
Marcel J. F. Stive - One of the best experts on this subject based on the ideXlab platform.
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Tidal wave propagation along The Mekong deltaic coast
Estuarine Coastal and Shelf Science, 2019Co-Authors: Hung Manh Phan, Ad Reniers, Marcel J. F. StiveAbstract:Abstract A two-dimensional, barotropic numerical model was employed to investigate the dynamics of tidal wave propagation in the South China Sea with a particular interest for its characteristics along the Mekong deltaic coast. The study indicates that tidal waves propagate from the Pacific Ocean into the South China Sea mainly through the Luzon Strait (LS), where the K1 diurnal tide dominates due to a quarter wavelength resonance in this semi-enclosed basin, and that the incoming tidal waves from the Celebes open boundary play a more important role than those from the Andaman and Flores open boundaries. Previous studies have not explained why both adjacent seas including the South China Sea and the Gulf of Thailand are dominated by a diurnal tide, while a semidiurnal tide dominates along the eastern Mekong deltaic coast. By means of Green's law, continental shelf tidal resonance theory and standing wave theory, this study clarifies that the large amplified M2 semidiurnal amplitude leading to a prevailing mixed semidiurnal tide is caused not only by the shoaling effect and the continental shelf oscillation resonance phenomenon but also by the position on the standing wave anti-Node Line. Moreover, the finding of radial tidal currents occurring along the southern Mekong estuarine coast has not been revealed in earlier studies. Based on a number of numerical, geometrically schematised experiments, we suggest that the interaction between the large amplified amplitude near the shoreLine associated with the adjacent low amplitude band system, causing convex hydraulic gradients of tidal amplitude due to basin geometry as well as sloping topography, is the mechanism for developing these radial tidal current systems. The results reveal that wind monsoon climate could cause either damped or amplified tidal amplitudes around the Mekong deltaic coast of which approximately 2–3 cm is due to the changing atmospheric pressure, the tangential stress of wind over the water surface and wind enhanced bottom friction. Also, this study suggests that the tidal generating forces should be considered to achieve accurate model results depending on the geographical region of interest. Findings achieved from this study contribute to a deeper insight of tidal wave propagation from a deep ocean to a shallow flat basin similar to the South China Sea and its Mekong deltaic coast.