The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
Philip E. Rosenberg - One of the best experts on this subject based on the ideXlab platform.
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A reinvestigation of smectite illitization in experimental hydrothermal conditions: Results from X-ray diffraction and transmission electron microscopy—Discussion
American Mineralogist, 2011Co-Authors: Douglas Yates, Philip E. RosenbergAbstract:We were pleased to read that our multiphase illitization model (Yates and Rosenberg 1996, 1997, 1998) has been confirmed by further experimental studies (Ferrage et al. 2011). We agree that illitization is a dissolution-precipitation process following the Ostwald step rule in which metastable intermediate phases are transformed into end-member illite. Unfortunately, several misstatements and misconceptions about our previous studies are incorporated into the paper by Ferrage et al. (2011) and their experimental design is open to criticism. (1) The multiphase model of Yates and Rosenberg (1996) is not based on the Fundamental Particle concept as claimed by Ferrage et al. (2011), but it is consistent with it and has been used to elucidate the model. However, in a previous paper we state that “it is not possible to rule out the Markovian model (Altaner and Bethke 1988; Altaner and Ylagan 1997) based on solution equilibration studies alone inasmuch as MacEwan crystallites of different ordering types may behave as thermodynamic phases” (Rosenberg et al. 1990). (2) According to Ferrage et al. (2011), in our model smectite illitization occurs through the step-wise formation of thermodynamically stable mica-like phases. …
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a reinvestigation of smectite illitization in experimental hydrothermal conditions results from x ray diffraction and transmission electron microscopy discussion
American Mineralogist, 2011Co-Authors: Douglas Yates, Philip E. RosenbergAbstract:We were pleased to read that our multiphase illitization model (Yates and Rosenberg 1996, 1997, 1998) has been confirmed by further experimental studies (Ferrage et al. 2011). We agree that illitization is a dissolution-precipitation process following the Ostwald step rule in which metastable intermediate phases are transformed into end-member illite. Unfortunately, several misstatements and misconceptions about our previous studies are incorporated into the paper by Ferrage et al. (2011) and their experimental design is open to criticism. (1) The multiphase model of Yates and Rosenberg (1996) is not based on the Fundamental Particle concept as claimed by Ferrage et al. (2011), but it is consistent with it and has been used to elucidate the model. However, in a previous paper we state that “it is not possible to rule out the Markovian model (Altaner and Bethke 1988; Altaner and Ylagan 1997) based on solution equilibration studies alone inasmuch as MacEwan crystallites of different ordering types may behave as thermodynamic phases” (Rosenberg et al. 1990). (2) According to Ferrage et al. (2011), in our model smectite illitization occurs through the step-wise formation of thermodynamically stable mica-like phases. …
Guoqing Chang - One of the best experts on this subject based on the ideXlab platform.
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discovery of a weyl fermion state with fermi arcs in niobium arsenide
Nature Physics, 2015Co-Authors: Nasser Alidoust, Ilya Belopolski, Zhujun Yuan, Guang Bian, Tay Rong Chang, Hao Zheng, V N Strocov, Daniel S Sanchez, Guoqing ChangAbstract:Three types of fermions play a Fundamental role in our understanding of nature: Dirac, Majorana and Weyl. Whereas Dirac fermions have been known for decades, the latter two have not been observed as any Fundamental Particle in high-energy physics, and have emerged as a much-sought-out treasure in condensed matter physics. A Weyl semimetal is a novel crystal whose low-energy electronic excitations behave as Weyl fermions. It has received worldwide interest and is believed to open the next era of condensed matter physics after graphene and three-dimensional topological insulators. However, experimental research has been held back because Weyl semimetals are extremely rare in nature. Here, we present the experimental discovery of the Weyl semimetal state in an inversion-symmetry-breaking single-crystalline solid, niobium arsenide (NbAs). Utilizing the combination of soft X-ray and ultraviolet photoemission spectroscopy, we systematically study both the surface and bulk electronic structure of NbAs. We experimentally observe both the Weyl cones in the bulk and the Fermi arcs on the surface of this system. Our ARPES data, in agreement with our theoretical band structure calculations, identify the Weyl semimetal state in NbAs, which provides a real platform to test the potential of Weyltronics. Experiments show that niobium arsenide is a Weyl semimetal.
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theoretical discovery prediction weyl semimetal states in the taas material taas nbas nbp tap class
Nature Communications, 2015Co-Authors: Shinming Huang, Nasser Alidoust, Ilya Belopolski, Guang Bian, Guoqing Chang, Chicheng Lee, B Wang, Madhab Neupane, A Bansil, Hsin LinAbstract:The recent discoveries of Dirac fermions in graphene and on the surface of topological insulators have ignited worldwide interest in physics and materials science. A Weyl semimetal is an unusual crystal where electrons also behave as massless quasi-Particles but interestingly they are not Dirac fermions. These massless Particles, Weyl fermions, were originally considered in massless quantum electrodynamics but have not been observed as a Fundamental Particle in nature. A Weyl semimetal provides a condensed matter realization of Weyl fermions, leading to unique transport properties with novel device applications. Here, we THEORETICALLY identify the first Weyl semimetal in a class of stoichiometric materials (TaAs, NbAs, NbP, TaP), which break crystalline inversion symmetry, including TaAs, TaP, NbAs and NbP. Our first-principles calculation-based predictions on TaAs reveal the spin-polarized Weyl cones and Fermi arc surface states in this compound. We also observe pairs of Weyl points with the same chiral charge which project onto the same point in the surface Brillouin zone, giving rise to multiple Fermi arcs connecting to a given Weyl point. Our results show that TaAs is the first topological semimetal identified which does not depend on fine-tuning of chemical composition or magnetic order, greatly facilitating an exploration of Weyl physics in real materials. (Note added: This theoretical prediction of November 2014 (see paper in Nature Communications) was the basis for the first experimental discovery of Weyl Fermions and topological Fermi arcs in TaAs recently published in Science (2015) at this http URL)
Douglas Yates - One of the best experts on this subject based on the ideXlab platform.
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A reinvestigation of smectite illitization in experimental hydrothermal conditions: Results from X-ray diffraction and transmission electron microscopy—Discussion
American Mineralogist, 2011Co-Authors: Douglas Yates, Philip E. RosenbergAbstract:We were pleased to read that our multiphase illitization model (Yates and Rosenberg 1996, 1997, 1998) has been confirmed by further experimental studies (Ferrage et al. 2011). We agree that illitization is a dissolution-precipitation process following the Ostwald step rule in which metastable intermediate phases are transformed into end-member illite. Unfortunately, several misstatements and misconceptions about our previous studies are incorporated into the paper by Ferrage et al. (2011) and their experimental design is open to criticism. (1) The multiphase model of Yates and Rosenberg (1996) is not based on the Fundamental Particle concept as claimed by Ferrage et al. (2011), but it is consistent with it and has been used to elucidate the model. However, in a previous paper we state that “it is not possible to rule out the Markovian model (Altaner and Bethke 1988; Altaner and Ylagan 1997) based on solution equilibration studies alone inasmuch as MacEwan crystallites of different ordering types may behave as thermodynamic phases” (Rosenberg et al. 1990). (2) According to Ferrage et al. (2011), in our model smectite illitization occurs through the step-wise formation of thermodynamically stable mica-like phases. …
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a reinvestigation of smectite illitization in experimental hydrothermal conditions results from x ray diffraction and transmission electron microscopy discussion
American Mineralogist, 2011Co-Authors: Douglas Yates, Philip E. RosenbergAbstract:We were pleased to read that our multiphase illitization model (Yates and Rosenberg 1996, 1997, 1998) has been confirmed by further experimental studies (Ferrage et al. 2011). We agree that illitization is a dissolution-precipitation process following the Ostwald step rule in which metastable intermediate phases are transformed into end-member illite. Unfortunately, several misstatements and misconceptions about our previous studies are incorporated into the paper by Ferrage et al. (2011) and their experimental design is open to criticism. (1) The multiphase model of Yates and Rosenberg (1996) is not based on the Fundamental Particle concept as claimed by Ferrage et al. (2011), but it is consistent with it and has been used to elucidate the model. However, in a previous paper we state that “it is not possible to rule out the Markovian model (Altaner and Bethke 1988; Altaner and Ylagan 1997) based on solution equilibration studies alone inasmuch as MacEwan crystallites of different ordering types may behave as thermodynamic phases” (Rosenberg et al. 1990). (2) According to Ferrage et al. (2011), in our model smectite illitization occurs through the step-wise formation of thermodynamically stable mica-like phases. …
Nasser Alidoust - One of the best experts on this subject based on the ideXlab platform.
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discovery of a weyl fermion state with fermi arcs in niobium arsenide
Nature Physics, 2015Co-Authors: Nasser Alidoust, Ilya Belopolski, Zhujun Yuan, Guang Bian, Tay Rong Chang, Hao Zheng, V N Strocov, Daniel S Sanchez, Guoqing ChangAbstract:Three types of fermions play a Fundamental role in our understanding of nature: Dirac, Majorana and Weyl. Whereas Dirac fermions have been known for decades, the latter two have not been observed as any Fundamental Particle in high-energy physics, and have emerged as a much-sought-out treasure in condensed matter physics. A Weyl semimetal is a novel crystal whose low-energy electronic excitations behave as Weyl fermions. It has received worldwide interest and is believed to open the next era of condensed matter physics after graphene and three-dimensional topological insulators. However, experimental research has been held back because Weyl semimetals are extremely rare in nature. Here, we present the experimental discovery of the Weyl semimetal state in an inversion-symmetry-breaking single-crystalline solid, niobium arsenide (NbAs). Utilizing the combination of soft X-ray and ultraviolet photoemission spectroscopy, we systematically study both the surface and bulk electronic structure of NbAs. We experimentally observe both the Weyl cones in the bulk and the Fermi arcs on the surface of this system. Our ARPES data, in agreement with our theoretical band structure calculations, identify the Weyl semimetal state in NbAs, which provides a real platform to test the potential of Weyltronics. Experiments show that niobium arsenide is a Weyl semimetal.
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theoretical discovery prediction weyl semimetal states in the taas material taas nbas nbp tap class
Nature Communications, 2015Co-Authors: Shinming Huang, Nasser Alidoust, Ilya Belopolski, Guang Bian, Guoqing Chang, Chicheng Lee, B Wang, Madhab Neupane, A Bansil, Hsin LinAbstract:The recent discoveries of Dirac fermions in graphene and on the surface of topological insulators have ignited worldwide interest in physics and materials science. A Weyl semimetal is an unusual crystal where electrons also behave as massless quasi-Particles but interestingly they are not Dirac fermions. These massless Particles, Weyl fermions, were originally considered in massless quantum electrodynamics but have not been observed as a Fundamental Particle in nature. A Weyl semimetal provides a condensed matter realization of Weyl fermions, leading to unique transport properties with novel device applications. Here, we THEORETICALLY identify the first Weyl semimetal in a class of stoichiometric materials (TaAs, NbAs, NbP, TaP), which break crystalline inversion symmetry, including TaAs, TaP, NbAs and NbP. Our first-principles calculation-based predictions on TaAs reveal the spin-polarized Weyl cones and Fermi arc surface states in this compound. We also observe pairs of Weyl points with the same chiral charge which project onto the same point in the surface Brillouin zone, giving rise to multiple Fermi arcs connecting to a given Weyl point. Our results show that TaAs is the first topological semimetal identified which does not depend on fine-tuning of chemical composition or magnetic order, greatly facilitating an exploration of Weyl physics in real materials. (Note added: This theoretical prediction of November 2014 (see paper in Nature Communications) was the basis for the first experimental discovery of Weyl Fermions and topological Fermi arcs in TaAs recently published in Science (2015) at this http URL)
Hsin Lin - One of the best experts on this subject based on the ideXlab platform.
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theoretical discovery prediction weyl semimetal states in the taas material taas nbas nbp tap class
Nature Communications, 2015Co-Authors: Shinming Huang, Nasser Alidoust, Ilya Belopolski, Guang Bian, Guoqing Chang, Chicheng Lee, B Wang, Madhab Neupane, A Bansil, Hsin LinAbstract:The recent discoveries of Dirac fermions in graphene and on the surface of topological insulators have ignited worldwide interest in physics and materials science. A Weyl semimetal is an unusual crystal where electrons also behave as massless quasi-Particles but interestingly they are not Dirac fermions. These massless Particles, Weyl fermions, were originally considered in massless quantum electrodynamics but have not been observed as a Fundamental Particle in nature. A Weyl semimetal provides a condensed matter realization of Weyl fermions, leading to unique transport properties with novel device applications. Here, we THEORETICALLY identify the first Weyl semimetal in a class of stoichiometric materials (TaAs, NbAs, NbP, TaP), which break crystalline inversion symmetry, including TaAs, TaP, NbAs and NbP. Our first-principles calculation-based predictions on TaAs reveal the spin-polarized Weyl cones and Fermi arc surface states in this compound. We also observe pairs of Weyl points with the same chiral charge which project onto the same point in the surface Brillouin zone, giving rise to multiple Fermi arcs connecting to a given Weyl point. Our results show that TaAs is the first topological semimetal identified which does not depend on fine-tuning of chemical composition or magnetic order, greatly facilitating an exploration of Weyl physics in real materials. (Note added: This theoretical prediction of November 2014 (see paper in Nature Communications) was the basis for the first experimental discovery of Weyl Fermions and topological Fermi arcs in TaAs recently published in Science (2015) at this http URL)
