  In recent work it was shown that new anisotropic p-wave states of superfluid
3He can be stabilized within high porosity silica aerogel under uniform
positive strain [1]. In contrast, the equilibrium phase in an unstrained
aerogel, is the isotropic superfluid B-phase [2]. Here we report that this
phase stability depends on the sign of the strain. For negative strain of ~20%
achieved by compression, the B-phase can be made more stable than the
anisotropic A-phase resulting in a tricritical point for A, B, and normal
phases with a critical field of ~100 mT. From pulsed NMR measurements we
identify these phases and the orientation of the angular momentum.
