New chiral phases of superfluid 3He stabilized by anisotropic silica aerogel

A rich variety of Fermi systems condense by forming bound pairs, including high-temperature(1) and heavy-fermion(2) superconductors, Sr2RuO4 (ref. 3), cold atomic gases(4) and superfluid He-3 (ref. 5). Some of these form exotic quantum states with non-zero orbital angular momentum. We have discovered, in the case of He-3, that anisotropic disorder, engineered from highly porous silica aerogel, stabilizes a chiral superfluid state that otherwise would not exist. Furthermore, we find that the chiral axis of this state can be uniquely oriented with the application of a magnetic field perpendicular to the aerogel anisotropy axis. At sufficiently low temperature we observe a sharp transition from a uniformly oriented chiral state to a disordered structure consistent with locally ordered domains, contrary to expectations for a superfluid glass phase(6).