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arXiv 1502.05769cond-mat.supr-con
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超导态狄拉克电子带间效应的迈斯纳效应

Meissner Effect of Dirac Electrons in Superconducting State due to Inter-band Effect

Tomonari Mizoguchi, Masao Ogata

摘要:

固体中的狄拉克电子由于其线性色散关系和双带性质而显示出特有的物理性质。尽管人们对正常态狄拉克电子的输运现象进行了深入的研究,但对超导态狄拉克电子的输运现象还没有完全了解。特别是,由于线性色散的结果,电流算符的抗磁项不存在,因此不清楚超导状态下的狄拉克电子是否表现出迈斯纳效应(ME)。本文从Kubo公式出发,研究了超导态三维重Dirac电子的ME,阐明了Meissner核在带间贡献的作用下是有限的.狄拉克电子的这种ME机制与一般金属中电子的ME机制完全不同。我们的结果表明,即使当超导能隙消失时,迈斯纳核仍然是有限的。这是在狄拉克电子系统中不可避免的问题,如在以前的工作中所报道的。因此,我们使用减去正常状态贡献的处方。为了证明这一处方,我们开发了一个特定的模型,迈斯纳内核是由处方。我们还利用Dirac哈密顿量的非相对论极限导出了电子气的结果,并阐明了Meissner核的抗磁项可以看作是电子和正电子在Dirac模型下的带间贡献.

英文摘要:

Dirac electrons in solids show characteristic physical properties due to their linear dispersion relation and two-band nature. Although the transport phenomena of Dirac electrons in a normal state have intensively been studied, the transport phenomena in a superconducting state have not been fully understood. In particular, it is not clear whether Dirac electrons in a superconducting state show Meissner effect (ME), since a diamagnetic term of a current operator is absent as a result of the linear dispersion. We investigate the ME of three dimensional massive Dirac electrons in a superconducting state on the basis of Kubo formula, and clarify that Meissner kernel becomes finite by use of the inter-band contribution. This mechanism of the ME for Dirac electrons is completely different from that for the electrons in usual metals. Our result shows that the Meissner kernel remains finite even when the superconducting gap vanishes. This is an unavoidable problem in the Dirac electron system as reported in the previous works. Thus, we use a prescription in which we subtract the normal state contribution. In order to justify this prescription, we develop a specific model where the Meissner kernel is obtained by the prescription. We also derive the result for the electron gas by taking the non-relativistic limit of Dirac Hamiltonian, and clarify that the diamagnetic term of the Meissner kernel can be regarded as the inter-band contribution between electrons and positrons in terms of the Dirac model.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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