Contribution of the surface roughness of hexagonal crystal into the low temperature surface specific heat

Abstract

The effect of surface roughness on the low temperature surface specific heat of a hexagonal crystal is investigated in this paper by means of the Green's function method developed earlier, taking into account a considerable correction introduced into it. The surface whose contribution to the specific heat is being calculated is parallel on average to the basal plane of a hexagonal medium. An expression in analytical form is derived for the contribution of the weak roughness to the low temperature surface specific heat of a hexagonal medium which represents a correction to the result for the surface specific heat of a hexagonal crystal with a free flat boundary. In the limiting case of an isotropic medium the result coincides with that of earlier research. The analysis carried out proves that taking account of the surface roughness of a hexagonal crystal results on the whole in the increasing surface specific heat for roughness parameters corresponding to an optically smooth surface.