  Despite the great technological and scientific importance, a well-controlled
coupled behavior in magnetoelectric multiferroic materials at room temperature
remains challenging. We demonstrate that the self-ordered A2BBO6 (e.g., A = La,
B = Mn, and B = Ni) double perovskites provide a unique alternative opportunity
to control and/or to induce such behavior in oxides. In this paper, we outline
and discuss the various challenges and bottleneck issues related to this class
of materials using La2NiMnO6 as a prototype. Details of the synthesis
strategies, using pulsed laser deposition as a central tool, to obtain a
meticulous control over cation ordering is illustrated. The possible impact of
Ni/Mn cation ordering on the magnetic ground states, ferromagnetic transition
temperature, phonon behavior, and spin-phonon coupling are presented. Our
results are also compared with the current literature on related compounds.
