Growth and Physical properties of full chemically ordered manganites

Chemical doping is a widely used method to control materials’ physical properties. The dopants are usually randomly distributed. This unavoidably introduces disordering into the materials, which may affect the physical properties of the materials. This is especially true for electronic phase separation (EPS) phenomena in manganites, which is known to have a close correlation with disordering. In this work, we use superlattice growth to form chemically ordered manganites, and compare with conventional manganites whose chemical dopants are randomly distributed. Specifically, one unit cell LaMnO3 / one unit cell PrMnO3 / one unite cell CaMnO3 tricolor superlattices have been grown on NGO (110) and STO (100) substrates by laser molecular beam epitaxy, forming chemically ordered La_1/3Pr_1/3Ca_1/3MnO₃ (O-LPCMO) thin films. In stark contrast to the conventional La_1/3Pr_1/3Ca_1/3MnO₃ (R-LPCMO) thin films which are characterized by large scale EPS, the O-LPCMO films show no signs of EPS. This indicates that dopants induced disordering plays a critical role in large scale EPS in manganites. Our experimental results show that the O-LPCMO system is in a charge-ordered insulating state which is consistent with the first principle calculations.