Vortex matter in mesoscopic two-gap superconducting disks: Influence of Josephson and magnetic coupling
Vortex matter in mesoscopic two-gap superconducting disks: Influence of Josephson and magnetic coupling
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DOI：
10.1103/physrevb.81.214514
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发表时间：
2010-05
影响因子：
3.7
通讯作者：
R. Geurts;M. Milovsevi'c;F. Peeters
中科院分区：
文献类型：
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作者：
R. Geurts;M. Milovsevi'c;F. Peeters
在金兹堡-朗道理论的基础上，利用有限差分技术研究了双间隙介观超导体中两个电子凝聚体之间耦合的影响。在外加磁场中，我们推导了涡旋大小与样本大小和约瑟夫森耦合强度的关系。此外，我们还详细讨论了临界温度和场与耦合凝析油参数的关系。进一步证明了两种凝析物具有不同涡度的分数态的存在性和稳定性。此外，我们还发现了明显的不对称分数态，并展示了它们在实验中可观察到的磁响应。最后，引入凝聚体之间的磁耦合，重点研究了一带为II型，一带为I型的情况，即试样有效为I - x型。计算出的$M(H)$环显示出明显的混合型超导特征，我们发现这受到两种凝聚体中相干长度比的强烈影响。
The effects of the coupling between two electronic condensates in two-gap mesoscopic superconductors are studied within the Ginzburg-Landau theory using a finite difference technique. In applied magnetic field, we derive the dependency of the size of the vortex on the sample size and the strength of the Josephson coupling. In addition, we elaborate on the dependence of the critical temperature and field on the parameters of the coupled condensates. We demonstrate further the existence and stability of fractional states, for which the two condensates comprise different vorticity. Moreover, we also found pronounced asymmetric fractional states and we show their experimentally observable magnetic response. Finally, we introduce the magnetic coupling between condensates, and study in particular the case where one band is type II and the other is type I, i.e., the sample is effectively of I.x type. The calculated $M(H)$ loops show a clear signature of the mixed type of superconductivity, which we find to be strongly affected by the ratio of the coherence lengths in the two condensates.