论文标题

单极与球形谐波超导体:拓扑排斥,共存和稳定性

Monopole versus spherical harmonic superconductors: Topological repulsion, coexistence and stability

论文作者

Muñoz, Enrique, Soto-Garrido, Rodrigo, Juričić, Vladimir

论文摘要

单极谐波超导体(SC)在掺杂的Weyl半学中提出,作为封闭Weyl点的费米表面之间的配对,这是非常不寻常的,因为它具有从母体金属阶段继承的单极电荷。但是,该状态可以与更常规的球形谐波配对竞争,例如$ s $波。我们在这里证明,在弱耦合平均值BCS理论的框架内,单极和常规的球形谐波SC非常一致地共存,而当单极电荷的绝对值与球形谐波的角度量子数匹配时,则可以进行排斥。如我们所示,此功能是单极SC的拓扑性质的直接结果,我们将其配置为\ emph {拓扑排斥}。我们以常规$ s-$和$(p_x \ pm ip_y)的示例说明上述原则 - $波配对与monopole sc $ y _ _ { - 1,1,0}(θ,ϕ)$竞争,该$在参数空间的有限区域中共同存在,并分别撤销。此外,当节点上的化学电位不等,并且在存在类似点的带电杂质的情况下,S波配对更加稳定。由于相变是不连续的,靠近相边界,我们预测具有单极和琐事阶段(例如$ s $ wave)之间界面的Majorana表面模式将是单台sc的实验签名。

The monopole harmonic superconductor (SC), proposed in doped Weyl semimetals as a pairing between the Fermi surfaces enclosing the Weyl points, is rather unusual, as it features the monopole charge inherited from the parent metallic phase. However, this state can compete with more conventional spherical harmonic pairings, such as an $s$-wave. We here demonstrate, within the framework of the weak coupling mean-field BCS theory, that the monopole and a conventional spherical harmonic SC quite generically coexist, while the repulsion can take place when the absolute value of the monopole charge matches the angular momentum quantum number of the spherical harmonic. As we show, this feature is a direct consequence of the topological nature of the monopole SC, and we dub it \emph{topological repulsion}. We illustrate the above principle with the example of the conventional $s-$ and $(p_x\pm ip_y)-$wave pairings competing with the monopole SC $Y_{-1,1,0}(θ,ϕ)$, which coexist in a finite region of the parameter space, and repel, respectively. Furthermore, the s-wave pairing is more stable both when the chemical potentials at the nodes are unequal, and in the presence of point-like charged impurities. Since the phase transition is discontinuous, close to the phase boundary, we predict that the Majorana surface modes at the interfaces between domains featuring the monopole and the trivial phases, such as an $s-$wave, will be the experimental signature of the monopole SC.

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