Butsuri
Online ISSN : 2423-8872
Print ISSN : 0029-0181
ISSN-L : 0029-0181
Volume 72 , Issue 11
Showing 1-19 articles out of 19 articles from the selected issue
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  • Michihisa Yamamoto, Ivan V. Borzenets, Seigo Tarucha
    Type: Reviews
    2017 Volume 72 Issue 11 Pages 774-782
    Published: November 05, 2017
    Released: August 06, 2018
    JOURNAL FREE ACCESS

    Graphene-based Josephson junction is electrically tunable and can achieve a clean ballistic regime, where the mean free path of the graphene weak link exceeds the junction length. Systematic analysis of the critical current reveals theoretically expected critical current scaling in both diffusive and ballistic regimes. In the long diffusive regime, the critical current scales with the Thouless energy. In the ballistic regime, it scales with the superconductor gap when the junction length is smaller than the coherence length (short junction regime), otherwise it scales with the energy proportional to the inverse junction length (long junction regime). We also show that we can spatially split two electrons of a Cooper pair in graphene-superconductor junctions. In particular, supercurrent can flow through a quantum Hall state, where a Cooper pair splits into opposite edge channels through the electron-hole hybrid modes formed in the superconductor-quantum Hall interfaces.

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  • Masahiro Sato, Shintaro Takayoshi, Takashi Oka
    Type: Reviews
    2017 Volume 72 Issue 11 Pages 783-792
    Published: November 05, 2017
    Released: August 06, 2018
    JOURNAL FREE ACCESS

    In this article, we explain our theoretical proposals, ultrafast ways of controlling magnetic properties of solid (magnetization, spin chirality, spin currents, etc.) by laser. We first review the Floquet theorem, which is useful for the prediction of novel laser-induced phenomena, then we turn to our recent results. We cover the following topics: laser-induced magnetization growing process, laser-driven spin chirality and spin current in multiferroics, and topological spin liquid state realized by laser in the honeycomb Kitaev model.

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