Realization of theπ-state in junctions formed by multiband superconductors with a spin density wave
Realization of theπ-state in junctions formed by multiband superconductors with a spin density wave
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自旋密度波多带超导体形成的结中π态的实现
DOI：
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发表时间：
2012
期刊：
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通讯作者：
K. Efetov
中科院分区：
文献类型：
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作者：
A. Moor;A. Volkov;K. Efetov
使用多带超导体的简单模型（特别适用于铁基磷族化物），我们计算了由此类超导体组成的隧道结中的约瑟夫森电流 IJ 。我们采用隧道哈密顿方法和准经典格林函数。我们研究了超导（Ⅲ）和磁（SDW——自旋密度波）有序参数共存的情况以及仅存在超导有序参数的情况。我们表明，在非理想嵌套的情况下，当超导参数和磁序参数可能共存时，电流 IJ 取决于 SDW 磁化强度的相互方向，就像铁基磷化物中发生的情况一样。发现两种情况下π结的实现都是可能的。我们将没有 SDW 的多带超导体的结果与之前获得的结果进行比较，发现如果隧道矩阵元素是真实的，它们是一致的。如果这些元素很复杂，则约瑟夫森临界电流的公式中会出现一个新术语。
Using a simple model of multi-band superconductors, which can be applied in particular to Fe-based pnictides, we calculate the Josephson current IJ in a tunnel junction composed by such superconductors. We employ the tunneling Hamiltonian method and quasiclassical Green’s functions. We study both the case of coexistence of the superconducting (¢) and magnetic (SDW—spin density wave) order parameters and the case when only the superconducting order parameter exists. We show that the current IJ depends on the mutual orientation of magnetization of the SDW in the case of non-ideal nesting when the coexistence of superconducting and magnetic order parameters is possible as it takes place in Fe-based pnictides. It is foundthat the realization of the π-junction is possible in both cases. We compare our results for multi-band superconductors without the SDW with those obtained earlier and find that they coincide if the tunneling matrixelements arereal. Iftheseelements arecomplex, anewtermappearsintheformulafor theJosephson critical current.