论文标题
在列型超导体中的对称性，长度尺度，磁反应和天际链
Symmetries, Length Scales, Magnetic Response and Skyrmion Chains in Nematic Superconductors
论文作者
论文摘要
列神经系统是两个分量超导体，它们打破了旋转对称性，但表现出混合对称性，使空间旋转和相位差旋转。我们表明，这种诱导的空间各向异性的结果是混合正常模式，这是对系统围绕其基态的小扰动的线性响应，通常是伴侣的磁性和冷凝水自由度。我们将研究模式混合对列前系统磁反应的影响，因为应用场的强度增加。通常，我们表明耦合模式会产生垂直于应用场的磁场，从而导致磁反应自发扭曲方向。我们将研究Meissner效应的弱场以及更强大的应用领域，这些场产生了天际和复合涡流的混合物，形成了方向依赖性结合状态。我们还将计算结果的第一个和第二个关键字段的各向异性$ H_ {C_1} $和$ H_ {C_2} $。 $ H_ {C_1} \ Leq H \ Leq H_ {C_2} $中的Skyrmion晶格显示出结构上是复杂的，与传统超导体中的三角形或方形涡流Lattices相反。对于低场，系统的磁响应涉及平行的天空链的松散结合。随着外场的增加，链条相互吸引，从而导致晶胞在高施加场上变成三角形的过渡。这个独特的天空晶格和磁性扭曲是明确的指标，可以在实验上用于鉴定表现出列明超导性的材料。为了获得这些结果，我们开发并提出了一种新的方法，可以找到可以应用于其他类型的超导系统的涡旋晶格的晶胞。
Nematic systems are two component superconductors that break rotational symmetry, but exhibit a mixed symmetry that couples spatial rotations and phase difference rotations. We show that a consequence of this induced spatial anisotropy is mixed normal modes, that is the linear response to a small perturbation of the system about its ground state, generally couples magnetic and condensate degrees of freedom. We will study the effect of mode mixing on the magnetic response of a nematic system as the strength of applied field is increased. In general we show that the coupled modes generate magnetic field perpendicular to the applied field, causing the magnetic response to spontaneously twist direction. We will study this for the Meissner effect with weak fields and also for stronger applied fields, which produce a mixture of Skyrmions and composite vortices, forming orientation dependent bound states. We will also calculate the anisotropies of the resulting first and second critical fields $H_{c_1}$ and $H_{c_2}$. The Skyrmion lattices for $H_{c_1} \leq H \leq H_{c_2}$ in nematic superconductors are shown to be structurally complicated, in contrast to the triangular or square vortex lattices in conventional superconductors. For low fields the magnetic response of the system involves a loosely bound collection of parallel Skyrmion chains. As the external field is increased the chains attract one another, causing a transition where the unit cell becomes triangular for high applied fields. This unique Skyrmion lattice and the magnetic twisting are clear indicators that could be used experimentally to identify materials that exhibit nematic superconductivity. To obtain these results we develop and present a novel method to find the unit cell of a vortex lattice that can be applied to other kinds of superconducting systems.
