Anisotropy of Surface Stiffness, Growth Kinetics and Roughening Transition in ⁴He

Abstract

The solid-superfluid interface in ⁴He has attracted the attention of theoreticians and experimentalists during the last decade. Many essential problems concerning the thermodynamics and growth kinetics of the interface are still unsolved. The surface free energy α and the surface stiffness $\tilde{\alpha }{{i}_{ij}}$ ≡ α + +∂² α/∂θ _i ∂θ _j ( i=1,2; θ _i are the angles which determine the crystallographic orientahiori of the surface) determine the equilibrium properties of the interface. The growth dynamics are characterized by the kinetic growth coefficient K ≡ m v/δµ ( v is the growth rate along the normal to the surface $\vec{n}$, m is the ⁴He atomic mass, and δµ is the difference between the chemical potentials of the two phases) which is also a function of the surface orientation θ _i.