Effect of Magnetic Impurities on Superfluid He3

It is known that both magnetic and nonmagnetic impurities suppress unconventional superconductivity. Here we compare their effect on the paradigm unconventional superconductor, superfluid $^{3}\mathrm{He}$, using highly dilute silica aerogel. Switching magnetic to nonmagnetic scattering in the same physical system is achieved by coating the aerogel surface with $^{4}\mathrm{He}$. 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.