A POOR MANS INTERPRETATION OF THE NOZIERES-GALLET EFFECT

An interpretation of the effect proposed theoretically by Nozieres and Gallet (and experimentally observed in He-4), according to which the growth rate v of a crystal surface just below the roughening temperatu re T(R) is approximately linear in the disequilibrium DELTAmu, is give n in terms of the properties of the nucleation process in the presence of a characteristic length 1. The physical meaning of l is the distan ce over which information can propagate on the surface before a new la yer is formed. The nucleation barrier is lowered, because the size of a critical nucleus cannot exceed 1, the latter being in turn proportio nal to v-1/2. A self-consistency condition ensues. The effect takes pl ace when the correlation length xi, which diverges at T(R), becomes co mparable to l.