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Andrea Cavalleri - One of the best experts on this subject based on the ideXlab platform.

  • anomalous relaxation kinetics and charge density wave correlations in underDoped bapb1 xbixo3
    Proceedings of the National Academy of Sciences of the United States of America, 2017
    Co-Authors: D Nicoletti, Eliza Casandruc, P Giraldogallo, I R Fisher, Andrea Cavalleri
    Abstract:

    Superconductivity often emerges in proximity of other symmetry-breaking ground states, such as antiferromagnetism or charge-density-wave (CDW) order. However, the subtle interrelation of these phases remains poorly understood, and in some cases even the existence of short-range correlations for superconducting compositions is uncertain. In such circumstances, ultrafast experiments can provide new insights by tracking the relaxation kinetics following excitation at frequencies related to the broken-symmetry state. Here, we investigate the transient terahertz conductivity of BaPb1−xBixO3––a material for which superconductivity is “adjacent” to a competing CDW phase––after optical excitation tuned to the CDW absorption band. In insulating BaBiO3 we observed an increase in conductivity and a subsequent relaxation, which are consistent with quasiparticles injection across a rigid semiconducting gap. In the Doped Compound BaPb0.72Bi0.28O3 (superconducting below TC = 7 K), a similar response was also found immediately above TC. This observation evidences the presence of a robust gap up to T ≃ 40 K, which is presumably associated with short-range CDW correlations. A qualitatively different behavior was observed in the same material for T ≳ 40 K. Here, the photoconductivity was dominated by an enhancement in carrier mobility at constant density, suggestive of melting of the CDW correlations rather than excitation across an optical gap. The relaxation displayed a temperature-dependent, Arrhenius-like kinetics, suggestive of the crossing of a free-energy barrier between two phases. These results support the existence of short-range CDW correlations above TC in underDoped BaPb1−xBixO3, and provide information on the dynamical interplay between superconductivity and charge order.

  • anomalous relaxation kinetics and charge density wave correlations in underDoped bapb1 xbixo3
    arXiv: Superconductivity, 2017
    Co-Authors: D Nicoletti, Eliza Casandruc, P Giraldogallo, I R Fisher, Andrea Cavalleri
    Abstract:

    Superconductivity often emerges in proximity of other symmetry-breaking ground states, such as antiferromagnetism or charge-density-wave (CDW) order. However, the subtle inter-relation of these phases remains poorly understood, and in some cases even the existence of short-range correlations for superconducting compositions is uncertain. In such circumstances, ultrafast experiments can provide new insights, by tracking the relaxation kinetics following excitation at frequencies related to the broken symmetry state. Here, we investigate the transient terahertz conductivity of BaPb1-xBixO3 - a material for which superconductivity is adjacent to a competing CDW phase - after optical excitation tuned to the CDW absorption band. In insulating BaBiO3 we observed an increase in conductivity and a subsequent relaxation, which are consistent with quasiparticles injection across a rigid semiconducting gap. In the Doped Compound BaPb0.72Bi0.28O3 (superconducting below Tc=7K), a similar response was also found immediately above Tc. This observation evidences the presence of a robust gap up to T=40 K, which is presumably associated with short-range CDW correlations. A qualitatively different behaviour was observed in the same material fo T>40 K. Here, the photo-conductivity was dominated by an enhancement in carrier mobility at constant density, suggestive of melting of the CDW correlations rather than excitation across an optical gap. The relaxation displayed a temperature dependent, Arrhenius-like kinetics, suggestive of the crossing of a free-energy barrier between two phases. These results support the existence of short-range CDW correlations above Tc in underDoped BaPb1-xBixO3, and provide new information on the dynamical interplay between superconductivity and charge order.

I R Fisher - One of the best experts on this subject based on the ideXlab platform.

  • anomalous relaxation kinetics and charge density wave correlations in underDoped bapb1 xbixo3
    Proceedings of the National Academy of Sciences of the United States of America, 2017
    Co-Authors: D Nicoletti, Eliza Casandruc, P Giraldogallo, I R Fisher, Andrea Cavalleri
    Abstract:

    Superconductivity often emerges in proximity of other symmetry-breaking ground states, such as antiferromagnetism or charge-density-wave (CDW) order. However, the subtle interrelation of these phases remains poorly understood, and in some cases even the existence of short-range correlations for superconducting compositions is uncertain. In such circumstances, ultrafast experiments can provide new insights by tracking the relaxation kinetics following excitation at frequencies related to the broken-symmetry state. Here, we investigate the transient terahertz conductivity of BaPb1−xBixO3––a material for which superconductivity is “adjacent” to a competing CDW phase––after optical excitation tuned to the CDW absorption band. In insulating BaBiO3 we observed an increase in conductivity and a subsequent relaxation, which are consistent with quasiparticles injection across a rigid semiconducting gap. In the Doped Compound BaPb0.72Bi0.28O3 (superconducting below TC = 7 K), a similar response was also found immediately above TC. This observation evidences the presence of a robust gap up to T ≃ 40 K, which is presumably associated with short-range CDW correlations. A qualitatively different behavior was observed in the same material for T ≳ 40 K. Here, the photoconductivity was dominated by an enhancement in carrier mobility at constant density, suggestive of melting of the CDW correlations rather than excitation across an optical gap. The relaxation displayed a temperature-dependent, Arrhenius-like kinetics, suggestive of the crossing of a free-energy barrier between two phases. These results support the existence of short-range CDW correlations above TC in underDoped BaPb1−xBixO3, and provide information on the dynamical interplay between superconductivity and charge order.

  • anomalous relaxation kinetics and charge density wave correlations in underDoped bapb1 xbixo3
    arXiv: Superconductivity, 2017
    Co-Authors: D Nicoletti, Eliza Casandruc, P Giraldogallo, I R Fisher, Andrea Cavalleri
    Abstract:

    Superconductivity often emerges in proximity of other symmetry-breaking ground states, such as antiferromagnetism or charge-density-wave (CDW) order. However, the subtle inter-relation of these phases remains poorly understood, and in some cases even the existence of short-range correlations for superconducting compositions is uncertain. In such circumstances, ultrafast experiments can provide new insights, by tracking the relaxation kinetics following excitation at frequencies related to the broken symmetry state. Here, we investigate the transient terahertz conductivity of BaPb1-xBixO3 - a material for which superconductivity is adjacent to a competing CDW phase - after optical excitation tuned to the CDW absorption band. In insulating BaBiO3 we observed an increase in conductivity and a subsequent relaxation, which are consistent with quasiparticles injection across a rigid semiconducting gap. In the Doped Compound BaPb0.72Bi0.28O3 (superconducting below Tc=7K), a similar response was also found immediately above Tc. This observation evidences the presence of a robust gap up to T=40 K, which is presumably associated with short-range CDW correlations. A qualitatively different behaviour was observed in the same material fo T>40 K. Here, the photo-conductivity was dominated by an enhancement in carrier mobility at constant density, suggestive of melting of the CDW correlations rather than excitation across an optical gap. The relaxation displayed a temperature dependent, Arrhenius-like kinetics, suggestive of the crossing of a free-energy barrier between two phases. These results support the existence of short-range CDW correlations above Tc in underDoped BaPb1-xBixO3, and provide new information on the dynamical interplay between superconductivity and charge order.

P Giraldogallo - One of the best experts on this subject based on the ideXlab platform.

  • anomalous relaxation kinetics and charge density wave correlations in underDoped bapb1 xbixo3
    Proceedings of the National Academy of Sciences of the United States of America, 2017
    Co-Authors: D Nicoletti, Eliza Casandruc, P Giraldogallo, I R Fisher, Andrea Cavalleri
    Abstract:

    Superconductivity often emerges in proximity of other symmetry-breaking ground states, such as antiferromagnetism or charge-density-wave (CDW) order. However, the subtle interrelation of these phases remains poorly understood, and in some cases even the existence of short-range correlations for superconducting compositions is uncertain. In such circumstances, ultrafast experiments can provide new insights by tracking the relaxation kinetics following excitation at frequencies related to the broken-symmetry state. Here, we investigate the transient terahertz conductivity of BaPb1−xBixO3––a material for which superconductivity is “adjacent” to a competing CDW phase––after optical excitation tuned to the CDW absorption band. In insulating BaBiO3 we observed an increase in conductivity and a subsequent relaxation, which are consistent with quasiparticles injection across a rigid semiconducting gap. In the Doped Compound BaPb0.72Bi0.28O3 (superconducting below TC = 7 K), a similar response was also found immediately above TC. This observation evidences the presence of a robust gap up to T ≃ 40 K, which is presumably associated with short-range CDW correlations. A qualitatively different behavior was observed in the same material for T ≳ 40 K. Here, the photoconductivity was dominated by an enhancement in carrier mobility at constant density, suggestive of melting of the CDW correlations rather than excitation across an optical gap. The relaxation displayed a temperature-dependent, Arrhenius-like kinetics, suggestive of the crossing of a free-energy barrier between two phases. These results support the existence of short-range CDW correlations above TC in underDoped BaPb1−xBixO3, and provide information on the dynamical interplay between superconductivity and charge order.

  • anomalous relaxation kinetics and charge density wave correlations in underDoped bapb1 xbixo3
    arXiv: Superconductivity, 2017
    Co-Authors: D Nicoletti, Eliza Casandruc, P Giraldogallo, I R Fisher, Andrea Cavalleri
    Abstract:

    Superconductivity often emerges in proximity of other symmetry-breaking ground states, such as antiferromagnetism or charge-density-wave (CDW) order. However, the subtle inter-relation of these phases remains poorly understood, and in some cases even the existence of short-range correlations for superconducting compositions is uncertain. In such circumstances, ultrafast experiments can provide new insights, by tracking the relaxation kinetics following excitation at frequencies related to the broken symmetry state. Here, we investigate the transient terahertz conductivity of BaPb1-xBixO3 - a material for which superconductivity is adjacent to a competing CDW phase - after optical excitation tuned to the CDW absorption band. In insulating BaBiO3 we observed an increase in conductivity and a subsequent relaxation, which are consistent with quasiparticles injection across a rigid semiconducting gap. In the Doped Compound BaPb0.72Bi0.28O3 (superconducting below Tc=7K), a similar response was also found immediately above Tc. This observation evidences the presence of a robust gap up to T=40 K, which is presumably associated with short-range CDW correlations. A qualitatively different behaviour was observed in the same material fo T>40 K. Here, the photo-conductivity was dominated by an enhancement in carrier mobility at constant density, suggestive of melting of the CDW correlations rather than excitation across an optical gap. The relaxation displayed a temperature dependent, Arrhenius-like kinetics, suggestive of the crossing of a free-energy barrier between two phases. These results support the existence of short-range CDW correlations above Tc in underDoped BaPb1-xBixO3, and provide new information on the dynamical interplay between superconductivity and charge order.

Hisashi Konaka - One of the best experts on this subject based on the ideXlab platform.

Yichun Liu - One of the best experts on this subject based on the ideXlab platform.

  • a single eu2 activated high color rendering oxychloride white light phosphor for white light emitting diodes
    Light-Science & Applications, 2016
    Co-Authors: Pengpeng Dai, Xintong Zhang, Xi Chen, Xiuli Wang, Yan Jia, Xiaojun Wang, Yichun Liu
    Abstract:

    Single-phased, high-color-rendering index (CRI) white-light phosphors are emerging as potential phosphor-converted white-light-emitting diodes (WLEDs) and as an alternative to blends of tricolor phosphors. However, it is a challenge to create a high CRI white light from a single-Doped activator. Here, we present a high CRI (Ra = 91) white-light phosphor, Sr5(PO4)3-x(BO3)xCl:Eu2+, composed of Sr5(PO4)3Cl as the beginning member and Sr5(BO3)3Cl as the end member. This work utilized the solid-solution method, and tunable Eu2+ emission was achieved. Color-tunable Eu2+ emissions in response to structural variation were observed in Sr5(PO4)3-x(BO3)xCl solid solutions. This was further confirmed using X-ray Rietveld refinement, electron paramagnetic resonance spectroscopy, and in the photoluminescence spectra. The color-tunable emissions included the white light that originated from the combination of the blue emission of Sr5(PO4)3Cl:Eu2+ and an induced Eu2+ yellow emission at approximately 550 nm in the solid solution. Importantly, the white-light phosphors showed a greater R9 = 90.2 under excitation at 365 nm. This result has rarely been reported in the literature and is greater than that of (R9 = 14.3) commercial Y3Al5O12:Ce3+-based WLEDs. These findings demonstrate the great potential of Sr5(PO4)3-x(BO3)xCl:0.04Eu2+ as a white-light phosphor for near-UV phosphor-converted WLEDs. These results also provide a shortcut for developing a high CRI white-light phosphor from a single Eu2+-Doped Compound. A white light-emitting diode with a very high colour rendering index is made using a phosphor based on a europium-Doped oxychloride material. A team of scientists from China, Switzerland and the USA investigated the white-light phosphor Sr5(PO4)3−x(BO3)xCl:Eu2+. Its structural and electronic properties were characterized by X-ray diffraction analysis, photoluminescence spectroscopy, and fluorescence decay analysis of the phosphor. When excited by ultraviolet light (365 nanometres) from a light-emitting diode, the phosphor emitted broadband photoluminescence with peaks in the blue (446 nanometres) and yellow (550 nanometres) regions. These emission characteristics resulted in high-quality white light with a very high colour rendering index that was significantly better than those of existing commercial white light-emitting diodes based on the phosphor YAG:Ce3+, indicating the potential of this new phosphor.