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Katsuya Shimizu - One of the best experts on this subject based on the ideXlab platform.

  • superconductivity in room temperature stable electride and high pressure phases of alkali Metals
    Philosophical Transactions of the Royal Society A, 2015
    Co-Authors: Hideo Hosono, Satoru Matsuishi, Shigeki Tanaka, Atsushi Miyake, T Kagayama, Katsuya Shimizu
    Abstract:

    S-band Metals such as alkali and Alkaline Earth Metals do not undergo a superconducting transition (SCT) at ambient pressure, but their high-pressure phases do. By contrast, room-temperature stable electride [Ca24Al28O64]4+⋅4e− (C12A7:e−) in which anionic electrons in the crystallographic sub-nanometer-size cages have high s-character exhibits SCT at 0.2–0.4 K at ambient pressure. In this paper, we report that crystal and electronic structures of C12A7:e− are close to those of the high-pressure superconducting phase of alkali and Alkaline Earth Metals and the SCT of both materials is induced when electron nature at Fermi energy ( E F) switches from s- to sd-hybridized state.

  • superconductivity in room temperature stable electride and high pressure phases of alkali Metals
    Philosophical Transactions of the Royal Society A, 2015
    Co-Authors: Hideo Hosono, Satoru Matsuishi, Shigeki Tanaka, Atsushi Miyake, T Kagayama, Sung Wng Kim, Katsuya Shimizu
    Abstract:

    S-band Metals such as alkali and Alkaline Earth Metals do not undergo a superconducting transition (SCT) at ambient pressure, but their high-pressure phases do. By contrast, room-temperature stable electride [Ca24Al28O64]4+⋅4e− (C12A7:e−) in which anionic electrons in the crystallographic sub-nanometer-size cages have high s-character exhibits SCT at 0.2–0.4 K at ambient pressure. In this paper, we report that crystal and electronic structures of C12A7:e− are close to those of the high-pressure superconducting phase of alkali and Alkaline Earth Metals and the SCT of both materials is induced when electron nature at Fermi energy ( E F) switches from s- to sd-hybridized state.

Hideo Hosono - One of the best experts on this subject based on the ideXlab platform.

  • superconductivity in room temperature stable electride and high pressure phases of alkali Metals
    Philosophical Transactions of the Royal Society A, 2015
    Co-Authors: Hideo Hosono, Satoru Matsuishi, Shigeki Tanaka, Atsushi Miyake, T Kagayama, Katsuya Shimizu
    Abstract:

    S-band Metals such as alkali and Alkaline Earth Metals do not undergo a superconducting transition (SCT) at ambient pressure, but their high-pressure phases do. By contrast, room-temperature stable electride [Ca24Al28O64]4+⋅4e− (C12A7:e−) in which anionic electrons in the crystallographic sub-nanometer-size cages have high s-character exhibits SCT at 0.2–0.4 K at ambient pressure. In this paper, we report that crystal and electronic structures of C12A7:e− are close to those of the high-pressure superconducting phase of alkali and Alkaline Earth Metals and the SCT of both materials is induced when electron nature at Fermi energy ( E F) switches from s- to sd-hybridized state.

  • superconductivity in room temperature stable electride and high pressure phases of alkali Metals
    Philosophical Transactions of the Royal Society A, 2015
    Co-Authors: Hideo Hosono, Satoru Matsuishi, Shigeki Tanaka, Atsushi Miyake, T Kagayama, Sung Wng Kim, Katsuya Shimizu
    Abstract:

    S-band Metals such as alkali and Alkaline Earth Metals do not undergo a superconducting transition (SCT) at ambient pressure, but their high-pressure phases do. By contrast, room-temperature stable electride [Ca24Al28O64]4+⋅4e− (C12A7:e−) in which anionic electrons in the crystallographic sub-nanometer-size cages have high s-character exhibits SCT at 0.2–0.4 K at ambient pressure. In this paper, we report that crystal and electronic structures of C12A7:e− are close to those of the high-pressure superconducting phase of alkali and Alkaline Earth Metals and the SCT of both materials is induced when electron nature at Fermi energy ( E F) switches from s- to sd-hybridized state.

Shuichi Murakami - One of the best experts on this subject based on the ideXlab platform.

  • topological dirac nodal lines and surface charges in fcc Alkaline Earth Metals
    Nature Communications, 2017
    Co-Authors: Motoaki Hirayama, Ryo Okugawa, Takashi Miyake, Shuichi Murakami
    Abstract:

    In nodal-line semiMetals, the gaps close along loops in k space, which are not at high-symmetry points. Typical mechanisms for the emergence of nodal lines involve mirror symmetry and the π Berry phase. Here we show via ab initio calculations that fcc calcium (Ca), strontium (Sr) and ytterbium (Yb) have topological nodal lines with the π Berry phase near the Fermi level, when spin–orbit interaction is neglected. In particular, Ca becomes a nodal-line semimetal at high pressure. Owing to nodal lines, the Zak phase becomes either π or 0, depending on the wavevector k, and the π Zak phase leads to surface polarization charge. Carriers eventually screen it, leaving behind large surface dipoles. In materials with nodal lines, both the large surface polarization charge and the emergent drumhead surface states enhance Rashba splitting when heavy adatoms are present, as we have shown to occur in Bi/Sr(111) and in Bi/Ag(111). The nodal-line semiMetals exhibit an intriguing interplay between topology, symmetry and materials science. Here, Hirayamaet al. predict a nodal-line semimetal phase resulting from the pi Berry phase in Alkaline-Earth Metals, and show that the nodal lines give rise to surface polarization charge, which is eventually screened by bulk carriers.

  • topological dirac nodal lines and surface charges in fcc Alkaline Earth Metals
    Nature Communications, 2017
    Co-Authors: Motoaki Hirayama, Ryo Okugawa, Takashi Miyake, Shuichi Murakami
    Abstract:

    In nodal-line semiMetals, the gaps close along loops in k space, which are not at high-symmetry points. Typical mechanisms for the emergence of nodal lines involve mirror symmetry and the π Berry phase. Here we show via ab initio calculations that fcc calcium (Ca), strontium (Sr) and ytterbium (Yb) have topological nodal lines with the π Berry phase near the Fermi level, when spin-orbit interaction is neglected. In particular, Ca becomes a nodal-line semimetal at high pressure. Owing to nodal lines, the Zak phase becomes either π or 0, depending on the wavevector k, and the π Zak phase leads to surface polarization charge. Carriers eventually screen it, leaving behind large surface dipoles. In materials with nodal lines, both the large surface polarization charge and the emergent drumhead surface states enhance Rashba splitting when heavy adatoms are present, as we have shown to occur in Bi/Sr(111) and in Bi/Ag(111).

T Kagayama - One of the best experts on this subject based on the ideXlab platform.

  • superconductivity in room temperature stable electride and high pressure phases of alkali Metals
    Philosophical Transactions of the Royal Society A, 2015
    Co-Authors: Hideo Hosono, Satoru Matsuishi, Shigeki Tanaka, Atsushi Miyake, T Kagayama, Katsuya Shimizu
    Abstract:

    S-band Metals such as alkali and Alkaline Earth Metals do not undergo a superconducting transition (SCT) at ambient pressure, but their high-pressure phases do. By contrast, room-temperature stable electride [Ca24Al28O64]4+⋅4e− (C12A7:e−) in which anionic electrons in the crystallographic sub-nanometer-size cages have high s-character exhibits SCT at 0.2–0.4 K at ambient pressure. In this paper, we report that crystal and electronic structures of C12A7:e− are close to those of the high-pressure superconducting phase of alkali and Alkaline Earth Metals and the SCT of both materials is induced when electron nature at Fermi energy ( E F) switches from s- to sd-hybridized state.

  • superconductivity in room temperature stable electride and high pressure phases of alkali Metals
    Philosophical Transactions of the Royal Society A, 2015
    Co-Authors: Hideo Hosono, Satoru Matsuishi, Shigeki Tanaka, Atsushi Miyake, T Kagayama, Sung Wng Kim, Katsuya Shimizu
    Abstract:

    S-band Metals such as alkali and Alkaline Earth Metals do not undergo a superconducting transition (SCT) at ambient pressure, but their high-pressure phases do. By contrast, room-temperature stable electride [Ca24Al28O64]4+⋅4e− (C12A7:e−) in which anionic electrons in the crystallographic sub-nanometer-size cages have high s-character exhibits SCT at 0.2–0.4 K at ambient pressure. In this paper, we report that crystal and electronic structures of C12A7:e− are close to those of the high-pressure superconducting phase of alkali and Alkaline Earth Metals and the SCT of both materials is induced when electron nature at Fermi energy ( E F) switches from s- to sd-hybridized state.

Atsushi Miyake - One of the best experts on this subject based on the ideXlab platform.

  • superconductivity in room temperature stable electride and high pressure phases of alkali Metals
    Philosophical Transactions of the Royal Society A, 2015
    Co-Authors: Hideo Hosono, Satoru Matsuishi, Shigeki Tanaka, Atsushi Miyake, T Kagayama, Katsuya Shimizu
    Abstract:

    S-band Metals such as alkali and Alkaline Earth Metals do not undergo a superconducting transition (SCT) at ambient pressure, but their high-pressure phases do. By contrast, room-temperature stable electride [Ca24Al28O64]4+⋅4e− (C12A7:e−) in which anionic electrons in the crystallographic sub-nanometer-size cages have high s-character exhibits SCT at 0.2–0.4 K at ambient pressure. In this paper, we report that crystal and electronic structures of C12A7:e− are close to those of the high-pressure superconducting phase of alkali and Alkaline Earth Metals and the SCT of both materials is induced when electron nature at Fermi energy ( E F) switches from s- to sd-hybridized state.

  • superconductivity in room temperature stable electride and high pressure phases of alkali Metals
    Philosophical Transactions of the Royal Society A, 2015
    Co-Authors: Hideo Hosono, Satoru Matsuishi, Shigeki Tanaka, Atsushi Miyake, T Kagayama, Sung Wng Kim, Katsuya Shimizu
    Abstract:

    S-band Metals such as alkali and Alkaline Earth Metals do not undergo a superconducting transition (SCT) at ambient pressure, but their high-pressure phases do. By contrast, room-temperature stable electride [Ca24Al28O64]4+⋅4e− (C12A7:e−) in which anionic electrons in the crystallographic sub-nanometer-size cages have high s-character exhibits SCT at 0.2–0.4 K at ambient pressure. In this paper, we report that crystal and electronic structures of C12A7:e− are close to those of the high-pressure superconducting phase of alkali and Alkaline Earth Metals and the SCT of both materials is induced when electron nature at Fermi energy ( E F) switches from s- to sd-hybridized state.