A General Theory for Crystalline Order-Disorder Phase Coexistence Interfaces

A general theory is proposed to reveal the universal properties of crystalline order-disorder phase coexistence interfaces, in particular, the surface energy anisotropy and the decaying of atomic ordering into the disorder phase. The proposed theory is rooted in a Ginzburg-Landau free energy in which multiple order parameters are employed to represent amplitudes of density waves of desired symmetries. A universal relation between the underlying lattice symmetry and the surface energy anisotropy is derived. In addition, we show analytically how the Ginzburg-Landau free energy landscape affects the magnitude of interfacial anisotropy and the decaying profile of atomic ordering across the interface, which is relevant in connecting the interatomic potential of materials to their corresponding surface properties.