Quasiclassical Green's function in slab geometry: Application to A-B transition of superfluid3He in a slab

Abstract

We show that the quasiclassical Green's function method can be used in slab geometries when the separation is much longer than the Fermi wavelength; consequently, quantum interference effects due to the double walls can be averaged out. We apply the quasiclassical method to the A-B transition of superfluid3He in a slab with specular walls at arbitrary temperature. We consider the phase transition between the planar state and the BW state within the weak coupling theory. The phase transition is shown to be of second kind at all temperatures. We obtain the critical size at which the B phase becomes unstable as a function of temperature. AtT=0 K and at SVP, the critical size is estimated to be 0.78 µm.