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Bernd Lorenz - One of the best experts on this subject based on the ideXlab platform.
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Ba1-xNaxTi2Sb2O (0.0 <= x <= 0.33): A Layered Titanium-based Pnictide Oxide Superconductor
arXiv, 2012Co-Authors: Phuong Doan, Melissa Gooch, Joshua Tapp, Angela Möller, Zhongjia Tang, Paul C W Chu, Bernd Lorenz, A. M. GuloyAbstract:A new layered Ti-based pnictide oxide superconductor, Ba1-xNaxTi2Sb2O (0.0 <= x <= 0.33), is reported. X-ray studies reveal it crystallizes in the tetragonal CeCr2Si2C structure. The undoped parent compound, BaTi2Sb2O (P4/mmm; a=4.1196(1){\AA}; c=8.0951(2){\AA}), exhibits a CDW/SDW transition at 54K. Upon chemical doping with Na, the CDW/SDW transition is systematically suppressed and super-conductivity arises with the critical temperatures, Tc, increasing to 5.5 K. Bulk superconductivity is confirmed by resistivity, magnetic and heat capacity measurements. Like the high-Tc Cuprates and the iron pnictides, superconductivity in BaTi2Sb2O arises from an ordered state. Similarities and differences to the cuprate and iron pnictide supercon-ductors are discussed.
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Ba1-xNaxTi2Sb2O (0.0
Journal of the American Chemical Society, 2012Co-Authors: Phuong Doan, Melissa Gooch, Angela Mo, Zhongjia Tang, Bernd Lorenz, Joshua TappAbstract:A new layered Ti-based pnictide oxide superconductor, Ba1−xNaxTi2Sb2O (0.0 ≤ x ≤ 0.33), is reported. X-ray studies revealed that it crystallizes in the tetragonal CeCr2Si2C structure. The undoped parent compound, BaTi2Sb2O[P4/mmm; a = 4.1196(1) Å; c = 8.0951(2) Å], exhibits a charge density wave (CDW)/spin density wave (SDW) transition at 54 K. Upon chemical doping with Na, the CDW/SDW transition is systemati- cally suppressed, and superconductivity arises with the critical temperature (Tc) increasing to 5.5 K. Bulk superconductivity was confirmed by resistivity, magnetic, and heat capacity measurements. Like the high-Tc Cuprates and the iron pnictides, the superconductivity in BaTi2Sb2O arises from an ordered state. Similarities and differences between BaTi2Sb2O and the cuprate and iron pnictide superconductors are discussed. T
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Ba 1– x Na x Ti 2 Sb 2 O (0.0 ≤ x ≤ 0.33): A Layered Titanium-Based Pnictide Oxide Superconductor
Journal of the American Chemical Society, 2012Co-Authors: Phuong Doan, Melissa Gooch, Joshua Tapp, Angela Möller, Zhongjia Tang, Paul C W Chu, Bernd Lorenz, A. M. GuloyAbstract:A new layered Ti-based pnictide oxide superconductor, Ba1–xNaxTi2Sb2O (0.0 ≤ x ≤ 0.33), is reported. X-ray studies revealed that it crystallizes in the tetragonal CeCr2Si2C structure. The undoped parent compound, BaTi2Sb2O [P4/mmm; a = 4.1196(1) Å; c = 8.0951(2) Å], exhibits a charge density wave (CDW)/spin density wave (SDW) transition at 54 K. Upon chemical doping with Na, the CDW/SDW transition is systematically suppressed, and superconductivity arises with the critical temperature (Tc) increasing to 5.5 K. Bulk superconductivity was confirmed by resistivity, magnetic, and heat capacity measurements. Like the high-Tc Cuprates and the iron pnictides, the superconductivity in BaTi2Sb2O arises from an ordered state. Similarities and differences between BaTi2Sb2O and the cuprate and iron pnictide superconductors are discussed.
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The Nature of the Superconducting State in Rutheno-Cuprates
Ruthenate and Rutheno-Cuprate Materials, 2002Co-Authors: Bernd Lorenz, R. L. MengAbstract:The magnetism and superconductivity (SC) of rutheno-Cuprates RuSr2LCu2O8−δ (Ru1212) and RuSr2(L,Ce)2Cu2O10+δ (Ru1222) were investigated, where L = Gd or Eu. The normal state carrier concentration p, the T c, the intragrain penetration depth λ, and the diamagnetic field-cooled magnetization were measured in various annealed rutheno-cuprate samples. The p varies with annealing only slightly (from 0.09 to 0.12 holes/CuO2), but the intragrain T c by a factor of 2.3 (from 17 to 40 K). The 1/λ 2, on the other hand, was enhanced more than tenfold (from 0.3 to 6 µm−2). The data are in disagreement with both the universal T c vs. p and T c vs. 1/λ 2 proposed for bulk Cuprates. These, together with the unusually large dT c/dH ≈ 100 K/T observed in both Ru1212 and Ru1222, suggest that even the intragrain SC of rutheno-Cuprates is granular. A Josephson-junction-array model was then proposed to interpret the data. The memory effect observed in Ru1222 far above the main magnetic transition temperature further suggests that the root of the granularity may be a phase separation, resulting in the mesoscopic ferromagnetic and antiferromagnetic species in these rutheno-Cuprates.
M K Chan - One of the best experts on this subject based on the ideXlab platform.
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hourglass dispersion and resonance of magnetic excitations in the superconducting state of the single layer cuprate hgba2cuo4 δ near optimal doping
Physical Review Letters, 2016Co-Authors: M K Chan, Y C Tang, C J Dorow, Jaehong Jeong, L Manginthro, M VeitAbstract:We use neutron scattering to study magnetic excitations near the antiferromagnetic wave vector in the underdoped single-layer cuprate HgBa_{2}CuO_{4+δ} (superconducting transition temperature T_{c}≈88 K, pseudogap temperature T^{*}≈220 K). The response is distinctly enhanced below T^{*} and exhibits a Y-shaped dispersion in the pseudogap state, whereas the superconducting state features an X-shaped (hourglass) dispersion and a further resonancelike enhancement. A large spin gap of about 40 meV is observed in both states. This phenomenology is reminiscent of that exhibited by bilayer Cuprates. The resonance spectral weight, irrespective of doping and compound, scales linearly with the putative binding energy of a spin exciton described by an itinerant-spin formalism.
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spectroscopic evidence for fermi liquid like energy and temperature dependence of the relaxation rate in the pseudogap phase of the Cuprates
Proceedings of the National Academy of Sciences of the United States of America, 2013Co-Authors: S I Mirzaei, D Stricker, Jason Hancock, Christophe Berthod, Antoine Georges, Erik Van Heumen, M K Chan, X ZhaoAbstract:Cuprate high-Tc superconductors exhibit enigmatic behavior in the nonsuperconducting state. For carrier concentrations near “optimal doping” (with respect to the highest Tcs) the transport and spectroscopic properties are unlike those of a Landau–Fermi liquid. On the Mott-insulating side of the optimal carrier concentration, which corresponds to underdoping, a pseudogap removes quasi-particle spectral weight from parts of the Fermi surface and causes a breakup of the Fermi surface into disconnected nodal and antinodal sectors. Here, we show that the near-nodal excitations of underdoped Cuprates obey Fermi liquid behavior. The lifetime τ(ω, T) of a quasi-particle depends on its energy ω as well as on the temperature T. For a Fermi liquid, 1/τ(ω, T) is expected to collapse on a universal function proportional to (ℏω)2 + (pπkBT)2. Magneto-transport experiments, which probe the properties in the limit ω = 0, have provided indications for the presence of a T2 dependence of the dc (ω = 0) resistivity of different cuprate materials. However, Fermi liquid behavior is very much about the energy dependence of the lifetime, and this can only be addressed by spectroscopic techniques. Our optical experiments confirm the aforementioned universal ω- and T dependence of 1/τ(ω, T), with p ∼ 1.5. Our data thus provide a piece of evidence in favor of a Fermi liquid-like scenario of the pseudogap phase of the Cuprates.
Phuong Doan - One of the best experts on this subject based on the ideXlab platform.
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Ba1-xNaxTi2Sb2O (0.0 <= x <= 0.33): A Layered Titanium-based Pnictide Oxide Superconductor
arXiv, 2012Co-Authors: Phuong Doan, Melissa Gooch, Joshua Tapp, Angela Möller, Zhongjia Tang, Paul C W Chu, Bernd Lorenz, A. M. GuloyAbstract:A new layered Ti-based pnictide oxide superconductor, Ba1-xNaxTi2Sb2O (0.0 <= x <= 0.33), is reported. X-ray studies reveal it crystallizes in the tetragonal CeCr2Si2C structure. The undoped parent compound, BaTi2Sb2O (P4/mmm; a=4.1196(1){\AA}; c=8.0951(2){\AA}), exhibits a CDW/SDW transition at 54K. Upon chemical doping with Na, the CDW/SDW transition is systematically suppressed and super-conductivity arises with the critical temperatures, Tc, increasing to 5.5 K. Bulk superconductivity is confirmed by resistivity, magnetic and heat capacity measurements. Like the high-Tc Cuprates and the iron pnictides, superconductivity in BaTi2Sb2O arises from an ordered state. Similarities and differences to the cuprate and iron pnictide supercon-ductors are discussed.
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Ba1-xNaxTi2Sb2O (0.0
Journal of the American Chemical Society, 2012Co-Authors: Phuong Doan, Melissa Gooch, Angela Mo, Zhongjia Tang, Bernd Lorenz, Joshua TappAbstract:A new layered Ti-based pnictide oxide superconductor, Ba1−xNaxTi2Sb2O (0.0 ≤ x ≤ 0.33), is reported. X-ray studies revealed that it crystallizes in the tetragonal CeCr2Si2C structure. The undoped parent compound, BaTi2Sb2O[P4/mmm; a = 4.1196(1) Å; c = 8.0951(2) Å], exhibits a charge density wave (CDW)/spin density wave (SDW) transition at 54 K. Upon chemical doping with Na, the CDW/SDW transition is systemati- cally suppressed, and superconductivity arises with the critical temperature (Tc) increasing to 5.5 K. Bulk superconductivity was confirmed by resistivity, magnetic, and heat capacity measurements. Like the high-Tc Cuprates and the iron pnictides, the superconductivity in BaTi2Sb2O arises from an ordered state. Similarities and differences between BaTi2Sb2O and the cuprate and iron pnictide superconductors are discussed. T
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Ba 1– x Na x Ti 2 Sb 2 O (0.0 ≤ x ≤ 0.33): A Layered Titanium-Based Pnictide Oxide Superconductor
Journal of the American Chemical Society, 2012Co-Authors: Phuong Doan, Melissa Gooch, Joshua Tapp, Angela Möller, Zhongjia Tang, Paul C W Chu, Bernd Lorenz, A. M. GuloyAbstract:A new layered Ti-based pnictide oxide superconductor, Ba1–xNaxTi2Sb2O (0.0 ≤ x ≤ 0.33), is reported. X-ray studies revealed that it crystallizes in the tetragonal CeCr2Si2C structure. The undoped parent compound, BaTi2Sb2O [P4/mmm; a = 4.1196(1) Å; c = 8.0951(2) Å], exhibits a charge density wave (CDW)/spin density wave (SDW) transition at 54 K. Upon chemical doping with Na, the CDW/SDW transition is systematically suppressed, and superconductivity arises with the critical temperature (Tc) increasing to 5.5 K. Bulk superconductivity was confirmed by resistivity, magnetic, and heat capacity measurements. Like the high-Tc Cuprates and the iron pnictides, the superconductivity in BaTi2Sb2O arises from an ordered state. Similarities and differences between BaTi2Sb2O and the cuprate and iron pnictide superconductors are discussed.
Joshua Tapp - One of the best experts on this subject based on the ideXlab platform.
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Ba1-xNaxTi2Sb2O (0.0 <= x <= 0.33): A Layered Titanium-based Pnictide Oxide Superconductor
arXiv, 2012Co-Authors: Phuong Doan, Melissa Gooch, Joshua Tapp, Angela Möller, Zhongjia Tang, Paul C W Chu, Bernd Lorenz, A. M. GuloyAbstract:A new layered Ti-based pnictide oxide superconductor, Ba1-xNaxTi2Sb2O (0.0 <= x <= 0.33), is reported. X-ray studies reveal it crystallizes in the tetragonal CeCr2Si2C structure. The undoped parent compound, BaTi2Sb2O (P4/mmm; a=4.1196(1){\AA}; c=8.0951(2){\AA}), exhibits a CDW/SDW transition at 54K. Upon chemical doping with Na, the CDW/SDW transition is systematically suppressed and super-conductivity arises with the critical temperatures, Tc, increasing to 5.5 K. Bulk superconductivity is confirmed by resistivity, magnetic and heat capacity measurements. Like the high-Tc Cuprates and the iron pnictides, superconductivity in BaTi2Sb2O arises from an ordered state. Similarities and differences to the cuprate and iron pnictide supercon-ductors are discussed.
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Ba1-xNaxTi2Sb2O (0.0
Journal of the American Chemical Society, 2012Co-Authors: Phuong Doan, Melissa Gooch, Angela Mo, Zhongjia Tang, Bernd Lorenz, Joshua TappAbstract:A new layered Ti-based pnictide oxide superconductor, Ba1−xNaxTi2Sb2O (0.0 ≤ x ≤ 0.33), is reported. X-ray studies revealed that it crystallizes in the tetragonal CeCr2Si2C structure. The undoped parent compound, BaTi2Sb2O[P4/mmm; a = 4.1196(1) Å; c = 8.0951(2) Å], exhibits a charge density wave (CDW)/spin density wave (SDW) transition at 54 K. Upon chemical doping with Na, the CDW/SDW transition is systemati- cally suppressed, and superconductivity arises with the critical temperature (Tc) increasing to 5.5 K. Bulk superconductivity was confirmed by resistivity, magnetic, and heat capacity measurements. Like the high-Tc Cuprates and the iron pnictides, the superconductivity in BaTi2Sb2O arises from an ordered state. Similarities and differences between BaTi2Sb2O and the cuprate and iron pnictide superconductors are discussed. T
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Ba 1– x Na x Ti 2 Sb 2 O (0.0 ≤ x ≤ 0.33): A Layered Titanium-Based Pnictide Oxide Superconductor
Journal of the American Chemical Society, 2012Co-Authors: Phuong Doan, Melissa Gooch, Joshua Tapp, Angela Möller, Zhongjia Tang, Paul C W Chu, Bernd Lorenz, A. M. GuloyAbstract:A new layered Ti-based pnictide oxide superconductor, Ba1–xNaxTi2Sb2O (0.0 ≤ x ≤ 0.33), is reported. X-ray studies revealed that it crystallizes in the tetragonal CeCr2Si2C structure. The undoped parent compound, BaTi2Sb2O [P4/mmm; a = 4.1196(1) Å; c = 8.0951(2) Å], exhibits a charge density wave (CDW)/spin density wave (SDW) transition at 54 K. Upon chemical doping with Na, the CDW/SDW transition is systematically suppressed, and superconductivity arises with the critical temperature (Tc) increasing to 5.5 K. Bulk superconductivity was confirmed by resistivity, magnetic, and heat capacity measurements. Like the high-Tc Cuprates and the iron pnictides, the superconductivity in BaTi2Sb2O arises from an ordered state. Similarities and differences between BaTi2Sb2O and the cuprate and iron pnictide superconductors are discussed.
Yu He - One of the best experts on this subject based on the ideXlab platform.
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raman and fluorescence characteristics of resonant inelastic x ray scattering from doped superconducting Cuprates
Scientific Reports, 2016Co-Authors: H Y Huang, Brian Moritz, T P Devereaux, Z Y Chen, Krzysztof Wohlfeld, W B Wu, J Okamoto, M Hashimoto, Yu HeAbstract:Measurements of spin excitations are essential for an understanding of spin-mediated pairing for superconductivity; and resonant inelastic X-ray scattering (RIXS) provides a considerable opportunity to probe high-energy spin excitations. However, whether RIXS correctly measures the collective spin excitations of doped superconducting Cuprates remains under debate. Here we demonstrate distinct Raman- and fluorescence-like RIXS excitations of Bi1.5Pb0.6Sr1.54CaCu2O8+δ. Combining photon-energy and momentum dependent RIXS measurements with theoretical calculations using exact diagonalization provides conclusive evidence that the Raman-like RIXS excitations correspond to collective spin excitations, which are magnons in the undoped Mott insulators and evolve into paramagnons in doped superconducting compounds. In contrast, the fluorescence-like shifts are due primarily to the continuum of particle-hole excitations in the charge channel. Our results show that under the proper experimental conditions RIXS indeed can be used to probe paramagnons in doped high-Tc cuprate superconductors.
