Procedure for LEED Ⅰ-Ⅴ structural analysis of metal oxide surfaces: Ca_(1.5)Sr_(0.5)RuO_4(001)

摘要

Transition metal oxides (TMOs) are famous for the intimate coupling between the lattice, electrons, and spin, creating exotic functionality. Creating a surface, breaking the symmetry, should result in lattice distortions that due to the close coupling could create different "surface phases." Historically it has been very difficult to use low energy electron diffraction Ⅰ- Ⅴ to quantitatively determine the surface structure of TMOs. A signature of this problem is the large values commonly reported in the literature of the Pendry reliability factor (R_P), which is used to quantify the agreement between experimental data and calculated diffraction. In this paper we describe a consistent procedure for determining the phase shifts using an optimized muffin-tin potential approach combined with an energy-dependent real and imaginary inner potential. This procedure is used to determine the surface structure of the layered TMO Ca_(1.5)Sr_(0.5)RuO_4. An acceptable Pendry reliability factor is achieved (R_P = 0.28).