Electronic and magnetic structures of double perovskite multifunctional La$_{2}$NiMnO$_{6}$ thin films*

Electronic and magnetic structures of the ordered double perovskite La$_{2}$NiMnO$_{6}$ (LNMO) thin films grown by pulsed laser deposition have been studied by x-ray absorption spectroscopy (XAS) and magnetic circular dichroism spectroscopy (XMCD). Based upon the results of XMCD, we find that the primary ion valence states to be Mn$^{4+}$/Ni$^{2+}$, and the ferromagnetism resulting from Mn$^{4+}$ -O - Ni$^{2+}$ superexchange interaction. Additionally, we show that the LNMO samples contain some Mn$^{3+}$ and Ni$^{3+}$ Jahn-Teller ions caused by oxygen or cation related defects. The orbital and spin magnetic moments of the Mn 3$d $and Ni 3$d $also have been deduced from the magneto-optical sum rules and compared with magnetization measurements.