Synthesis and properties of highly metallic orbital-ordered A-site manganites

In perovskite oxide materials, because of the insertion of multiple valence states ions (e.g., Mn in manganites) at atomic A-site (i.e., at the center of perovskite cubic cell), an enhancement of the ferromagnetic metallic state together with a strong orbital order of Mn-ions is established. Such a feature goes beyond the conventional theoretical framework for which the kinetic energy of the free charge carriers prevents the occurrence of a long-range orbital order. We do provide a complete physical characterization of these so-called A-site manganites by comparing transport and structural properties of La0.7Sr0.3MnO3 and LaMnO3 thin films with different excess Mn content and different oxygen content. A viable route to successfully grow such class of materials as a function of temperature and oxygen environment is provided. The observed multi-order phase coexistence opens unexplored perspectives toward the synthesis of new intrinsic multi-functional materials.