Superfluid quantum criticality in liquid ³He in anisotropic aerogel

Abstract

In the novel superfluid polar phase realized in liquid ³He in highly anisotropic aerogels, a quantum transition to the polar-distorted A (PdA) phase may occur at low but finite pressure Pc(0). It is shown that the nontrivial quantum dynamics of the critical fluctuation of PdA order is induced by the presence of both columnar impurity scattering leading to Anderson's theorem for the polar phase and the line node of the quasiparticle gap in the state, and that, in contrast to the situation of the normal to B-phase transition in isotropic aerogels, a weakly divergent behavior of the compressibility appears in the quantum critical region close to Pc(0).