Stability of superfluid 3He-B in compressed aerogel
  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. 
J.I.A. Li, A.M. Zimmerman, J. Pollanen, C.A. Collett, W.J. Gannon,   W.P. Halperin
cond-mat.supr-con