RHEED study of stepped (0 0 1) surface of strontium titanate

Abstract

Low-temperature RHEED technique was employed to study the structure of the regular-stepped (0 0 1) surface of strontium titanate with a miscut angle of 7° between crystallographic planes and real surfaces. Specific diffraction images resulting from miscut demonstrate an additional periodicity with a characteristic length equal to the width of terraces. A histogram method was applied in order to obtain a complete set of characteristic lattice parameters at the surface. A relaxation parallel to the surface was found to be different along and across steps. Surface lattice parameters exhibit several anomalies as a function of temperature, which are interpreted as surface phase transitions promoted by a surface anisotropy which removes the three-fold degeneracy of titanium-centered oxygen octahedra rotations around [0 0 1] axes.