Epitaxial thin films of biferroic Bi1−xLax 2NiMnO6 have been grown on SrTiO3 001 substrates. High resolution electron microscopy, energy-loss spectroscopy and synchrotron radiation have been used to demonstrate that, under appropriate growth conditions, stoichiometric, and fully oxidized thin films with long-range order of Ni2+ and Mn4+ ions can be obtained, despite the presence of randomly distributed dissimilar cations Bi, La at the A-site. This ordering leads to Ni2+
O
Mn4+ ferromagnetic interactions and its preservation in thin films is key for implementation of these biferroic materials in practical devices.