Hidden order as a source of interface superconductivity
Hidden order as a source of interface superconductivity
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DOI：
10.1103/physrevb.91.064511
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发表时间：
2015-01
影响因子：
3.7
通讯作者：
A. Moor;A. Volkov;K. Efetov
中科院分区：
文献类型：
--
作者：
A. Moor;A. Volkov;K. Efetov
在由不同材料组成的各种异质结构中，包括超导和非超导（在适当的掺杂和温度下）铜酸盐和铁基嘌呤，可以观察到界面超导性。在许多情况下，这种超导性的起源仍然不清楚。在这里，我们提出了具有竞争序参数的系统的界面超导的一般机制。我们假设表征材料的参数允许形成另一阶，如电荷或自旋密度波，在体中竞争和盛行超导性（隐藏超导性）。界面上的扩散电子散射抑制了这一阶，释放了超导性。我们的理论是基于适用于广泛系统的金兹堡-朗道方程的使用。我们证明了局部超导性出现在界面附近，超导序参量~$\Delta(x)$的空间依赖关系由Gross—Pitaevskii方程描述。求解这个方程，我们得到了~$\Delta(x)$出现时的温度和掺杂水平的量子化值。值得注意的是，即使在竞争序被轻微抑制的情况下，局部超导性也会出现，并且也可能出现在样品表面（表面超导性）。
Interfacial superconductivity is observed in a variety of heterostructures composed of different materials including superconducting and nonsuperconducting (at appropriate doping and temperatures) cuprates and iron-based pnictides. The origin of this superconductivity remains in many cases unclear. Here, we propose a general mechanism of interfacial superconductivity for systems with competing order parameters. We assume that parameters characterizing the material allow formation of another order like charge- or spin-density wave competing and prevailing superconductivity in the bulk (hidden superconductivity). Diffusive electron scattering on the interface results in a suppression of this order and releasing the superconductivity. Our theory is based on the use of Ginzburg--Landau equations applicable to a broad class of systems. We demonstrate that the local superconductivity appears in the vicinity of the interface and the spatial dependence of the superconducting order parameter~$\Delta(x)$ is described by the Gross--Pitaevskii equation. Solving this equation we obtain quantized values of temperature and doping levels at which~$\Delta(x)$ appears. Remarkably, the local superconductivity shows up even in the case when the rival order is only slightly suppressed and may arise also on the surface of the sample (surface superconductivity).