Imaging of 3d Mn orbitals in the ferromagnetic state for Ca-substituted manganite: Magnetic Compton investigation.

The 3d Mn orbitals in Pr0.25Ca0.25MnO3 (PCMO), in the ferromagnetic phase, were imaged by two-dimensional reconstruction of spin-polarized electron-momentum density projected along the [100] and [110] principal directions. The results were analyzed using a molecular-orbital scheme to understand the population distribution for the t2g and the eg states for Mn. The analysis shows that the t2g states are found to be half-filled, whereas, the eg states are dominated mainly by x2−z2-type orbitals for both projected [100] and [110] principal directions. The observance of preferential filling of the x2−z2-orbital type is consistent with a cooperative Jahn-Teller distortion of the MnO6 octahedra leading to a local tetragonal compression along the y axis for this system. As a result of this distortion, the 3y2−r2-type orbitals have a small population for PCMO; the ratio of the x2−z2-type orbitals to that of the 3y2−r2-type orbitals is greater than 2, similar to that seen for bilayered manganites. [ABSTRACT FROM AUTHOR]