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Physica
North-Holland
Physica

North-Holland

0921-4534

Physica/Journal Physica
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    Crack problem in a functionally graded superconductor cylinder under pulsed field magnetization

    Zhao, YufengLi, Tengjiao
    8页
    查看更多>>摘要：In the paper, the fracture of functionally graded superconductor under pulsed magnetic field is numerically analyzed, and the effect of electromagnetic stress and thermal stress on crack problem under pulsed magnetic field is studied. A FEM model based on H formula and heat transfer equation is proposed for the electromagnetic thermal behavior of inhomogeneous superconductors with central cracks. The influence of the gradient parameter eta of critical current density on the stress intensity factor was investigated. The numerical results show that the gradient parameter eta has a great influence on the change of stress intensity factor caused by electromagnetic force and thermal strain with time, which makes the crack easy to expand. In addition, the results show that the electromagnetic stress decreases gradually with the increase of crack length, and the thermal stress has a significant effect on the stress intensity factor.
      原文链接:
    • NSTL
    • Elsevier

    In-gap states of vortices at the surface of a topological insulator

    Schlottmann, P.
    5页
    查看更多>>摘要：By solving the Bogoliubov-de Gennes equations we study fermion bound states in the core of a vortex of a two-dimensional superconductor. The metallic surface states of a strong topological insulator become superconducting via proximity effect with an s-wave superconductor. The strong spin-orbit coupling locks the spin perpendicular to the momentum (Rashba interaction) giving rise to a zero-energy Majorana state. We investigate the case of a large first excitation energy of the order of the superconducting gap (delta(infinity)), i.e. for the Fermi level close to the apex of the Dirac cone. We obtain the local density of states (LDOS) for the bulk and the bound states. The particle-hole symmetry is broken in the LDOS for up-spin as a consequence of the spin-orbit coupling and the chirality of the vortex. On the other hand, the down-spin LDOS is particle-hole symmetric. The spin-polarization of the bound state peaks is studied in detail. We present a waterfall-like spectrum that shows that for a distance less than 3 times the coherence length xi from the core, the bound states can be observed.
      原文链接:
    • NSTL
    • Elsevier

    AC loss modeling of stacked HTS strips with economic analysis

    Shen, BoyangChen, YuZheng, PengfeiChe, Tong...
    11页
    查看更多>>摘要：In order to fabricate high-current superconducting conductors for engineering applications, the configuration of stacked high-temperature superconductor (HTS) strips is one of the most popular choices. AC losses in HTS stacks have been vastly studied, but the economic study towards the AC losses with respect to the capital investment and operating costs of HTS stacks is still missing. First, the modelling strategy using the finite element method (FEM) based on the H-formulation is explained, and the basic AC loss simulation of a single strip is verified by the Norris analytical methods. The HTS stack (16 strips) is used as an example, and the corresponding current distribution and magnetic field are analyzed. The relationship between the AC loss and current-carrying capability is studied for multiple stacks with different numbers of strips. Economic analysis is performed with regard to the relationship between the AC losses and investment/operating costs of multiple stacked HTS strips. In this article, the numerical modeling together with the economic analysis of stacked HTS strips bring new visions, which can be beneficial for the future designs of high-current superconducting conductors and cables.
      原文链接:
    • NSTL
    • Elsevier

    Superconducting critical temperature and isotope effect in the presence of electron-phonon,electron-paramagnon and electron-electron interactions in rhodium

    Bedi, Paramjeet Kaur Gumber
    5页
    查看更多>>摘要：An explicit expression for the superconducting critical temperature, T-C, and the exponent of vibrating ionic mass, alpha, has been derived in the simultaneous presence of attractive electron-phonon,repulsive electron-paramagnon and repulsive electron-electron interactions. The dependence of T-C, on these interactions is quite involved,but the observed value of T-C in transition element Rhodium can be explained using realistic physical parameters. Variation of T-C with lambda e(-s), electron-paramagnon coupling constant and Ee-s, electron-paramagnon energy, has also been studied. Rhodium shows inverse isotope effect in the presence of spin fluctuations.
      原文链接:
    • NSTL
    • Elsevier