On the Mn4+ R-line Intensity and energy in the perovskite layer of SrLaAlO4 and Sr2TiO4: A comparative study with LaAlO3 and SrTiO3

Abstract The Ruddlesden-Popper (RP) phases of SrLaAlO4 and Sr2TiO4 crystallize in the tetragonal A2BX4 structure that consists of an intergrowth of rocksalt (AX) and perovskite (ABX3) layers. In this article, the spectroscopic properties of Mn4+ embedded in the perovskite layer of SrLaAlO4 and Sr2TiO4 are compared with those in the perovskites, LaAlO3 and SrTiO3. For both RP phases, we find that energy of the zero-phonon line (ZPL; R-line) is essentially the same as in the corresponding perovskites. Despite the presence of inversion symmetry about the Mn4+ ion, the R-line is intense in the RP compounds while they appear with weak intensity in the emission spectrum of the corresponding perovskites. In SrLaAlO4 this is attributed to the removal of inversion symmetry by Al3+ vacancy and to the random distribution of Sr2+ and La3+ cations. In Sr2TiO4, the removal of inversion symmetry is hypothesized to occur via the off-center displacement of the Mn4+ ion.