Hole concentration dependence of Mn eg orbital state in bilayer manganites studied by magnetic Compton profile measurement Original Research Article

Magnetic Compton profiles (MCP) have been measured in the [100], [110] and [001] directions on the single crystals of La2−2xSr1+2xMn2O7 (x=0.30, 0.35 and 0.42) at 10 K. The occupation numbers in t2g and two eg type orbitals (x2−y2 and 3z2−r2) of Mn-3d state are evaluated from the line-shape analysis of MCPʹs in the [001] direction by using theoretical profiles derived from the ab initio calculations for (MnO6)8−cluster. It has been found that the eg state is dominated by the x2−y2 type orbital at every hole concentration, x, and the 3z2−r2 type orbital population decreases with increasing x. From the result, the connections of eg orbital state with the electron correlation effect, exchange interactions, lattice distortion and electronic inhomogeneity are discussed.