Interplay of Aerogel Anisotropy and Superfluid $^3$He Textures

The effect of aerogel anisotropy on the $^3$He superfluid order parameter and the relative stability of $A$ and $B$-phases has been investigated. We have performed pulsed NMR on $^3$He in high porosity aerogel samples that have different types of anisotropy, characterized with an optical, cross-polarization technique. One aerogel sample has $14.3\%$ growth-induced axial stretching. Its superfluid phase diagram is occupied by the $A$-phase. Linewidth analysis gives the distribution of the orbital angular momentum, $\vec{l}$. The orientation of $\vec{l}$ is consistent with an easy plane distribution that is perpendicular to the strain axis. A second aerogel sample is axially compressed mechanically by $22.5\%$. The major part of the zero magnetic field phase diagram is occupied by the $B$-phase. Additionally, our results show that aerogel anisotropy introduced by compressing and stretching have different orienting effects on the $^3$He superfluid order parameters. This work was supported by the National Science Foundation, DMR-1103625.