Zimmerman A M, Nguyen M D, Scott J W, Halperin W P
Northwestern University, Evanston, Illinois 60208, USA.
Phys Rev Lett. 2020 Jan 17;124(2):025302. doi: 10.1103/PhysRevLett.124.025302.
It is known that both magnetic and nonmagnetic impurities suppress unconventional superconductivity. Here we compare their effect on the paradigm unconventional superconductor, superfluid ^{3}He, using highly dilute silica aerogel. Switching magnetic to nonmagnetic scattering in the same physical system is achieved by coating the aerogel surface with ^{4}He. We find a marginal influence on the transition temperature itself. However, we have discovered that the A phase, which breaks time reversal symmetry, is strongly influenced, while the isotropic B phase is unchanged. Importantly, this occurs only if the impurities are anisotropically distributed on a global scale.
众所周知，磁性和非磁性杂质都会抑制非常规超导性。在此，我们使用高度稀释的二氧化硅气凝胶，比较它们对典型非常规超导体超流³He的影响。在同一物理系统中，通过用⁴He覆盖气凝胶表面，实现从磁性散射到非磁性散射的转变。我们发现这对转变温度本身的影响很小。然而，我们发现破坏时间反演对称性的A相受到强烈影响，而各向同性的B相则没有变化。重要的是，只有当杂质在全局尺度上呈各向异性分布时，才会出现这种情况。
