Effects of charge-orbital order-disorder phenomena on the unoccupied electronic states in the single-layered half-doped Pr 0.5 Ca 1.5 MnO 4

Here we report a study on the unoccupied states of the half-doped Pr0.5Ca1.5MnO4 (PCMO). Our investigation, based on temperature dependent x-ray absorption linear dichroism (XLD) and density-functional theory discloses the role of the charge-orbital ordering-disordering mechanisms on the unoccupied density of states. In particular, the lowest unoccupied band has a Mn eg d3z2−r2 character, proving that the physical properties of the two-dimensional (2D) PCMO are also determined by the out-of-plane orbital. Yet, the difference in energy between the d3z2−r2 and dx2−y2 states is observed to increase when a charge-orbital ordering is established, hence revealing that the Mn 3d electronic hopping is frustrated when the MnO6 cluster orthorhombic strain is increased. This finding addresses the question concerning the complex interplay between the in-plane and out-of plane orbitals in these 2D half-doped single layered manganites.