Anisotropic strong-coupling effects on superfluid He-3 in aerogels: Conventional spin-fluctuation approach

作者：Ikeda Ryusuke^*

来源：Physical Review B, 2015, 91(17): 174515.

DOI：10.1103/PhysRevB.91.174515

Motivated by recent experiments on liquid He-3 reporting emergence of novel superfluid phases in globally anisotropic aerogels, our previous theory on superfluid He-3 in globally anisotropic aerogels is extended to incorporate the effects of anisotropy of the quasiparticle scattering cross section on the strong-coupling (SC) contributions to the Ginzburg-Landau (GL) free energy on the basis of the spin-fluctuation (paramagnon) approach to the SC contributions developed by Brinkman et al. [Phys. Rev. A 10, 2386 (1974)]. In the globally isotropic case, impurity effects on the SC correction destabilize the A phase even at higher pressures of about 30 bar and make the B phase the only state in equilibrium, while SC contributions accompanied by a global stretched anisotropy to the GL quartic terms generally tend to broaden the stability region of the A phase compared with that of the B phase. In particular, in contrast to the cases in bulk and in the isotropic aerogel, the SC corrections to the GL quadratic terms are not negligible in the globally anisotropic case but may change the sign of the apparent anisotropy depending on the magnitude of the frequency cutoff of the normal paramagnon propagator. Based on this sign change of the apparent anisotropy, we discuss different strange observations on superfluid 3He in porous media such as the disappearance of the polar superfluid phase at higher pressures seen in nematically ordered aerogels and the absence of B and A phases with planar (I) over cap vector in a stretched aerogel.

• 出版日期2015-5-21