The 3$d$ Mn orbitals in Pr${}_{0.25}$Ca${}_{0.25}$MnO${}_3$ (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 $t_{2g}$ and the $e_g$ states for Mn. The analysis shows that the $t_{2g}$ states are found to be half-filled, whereas, the $e_g$ states are dominated mainly by $x^2-z^2$-type orbitals for both projected [100] and [110] principal directions. The observance of preferential filling of the $x^2-z^2$-orbital type is consistent with a cooperative Jahn-Teller distortion of the MnO${}_6$ octahedra leading to a local tetragonal compression along the $y$ axis for this system. As a result of this distortion, the 3$y^2-r^2$-type orbitals have a small population for PCMO; the ratio of the $x^2-z^2$-type orbitals to that of the 3$y^2-r^2$-type orbitals is greater than 2, similar to that seen for bilayered manganites.

• Received 12 July 2011

DOI:https://doi.org/10.1103/PhysRevB.85.045128