Figure 2

(a) Schematic view of tilt distortion in an octahedron with tilt angle (θ). (b) Enlargement of the white square marked in the LEED pattern in Fig. 1e, showing the integer spots (1, 2) and (2, 1) and the fractional order spot (3/2, 3/2) induced by tilt. (c) Normalized line profile along the dashed line in (b) for x = 0 (black solid line) and 0.16 (blue solid line) at 87 K. The inset shows the doping dependence of the fractional spot intensity.