Spin-fluctuation stabilization of anisotropic superfluid states

Abstract

The role spin fluctuations play in determining the stable superfluid phases of ${\mathrm{He}}^{3}$ is investigated. It is shown that the feedback effects of the gap on the spin fluctuations can stabilize the anisotropic Anderson-Morel (AM) state if they are sufficiently strong. The effect is calculated both near ${T}_{c}$ and at zero temperature. It is found that the Balian-Werthamer (BW) state is more stable at low temperatures and that the slope of the calculated transition from the AM to BW states qualitatively agrees with the experimental slope of the $A \mathrm{to} B$ transition as a function of pressure.