Phase Separation in Ferromagnetic/Charge-ordered Superlattices

The coexistence of ferromagnetic metal (FFM) and charge-ordered insulator (COI) observed in manganites, such as La$_{5/8-y}$Pr$_{y}$Ca$_{3/8}$MnO$_{3}$, has been an intensive focus in the study of transition metal oxides (TMO). Theories related to structural nanoscale disorder of charge carrier dopants and self-organization caused by an intrinsic elastic energy landscape have been proposed. To understand the subtle balance and competition between the different electronic phases, we have grown La$_{5/8}$Ca$_{3/8}$MnO$_{3}$/Pr$_{5/8}$Ca$_{3/8}$MnO$_{3}$ superlattices with different stacking periods in order to control the chemical ordering of La/Pr ions and thus the elastic energy landscape. The magnetic and transport properties of FM/CO superlattices as well as La/Pr disordered La$_{5/16}$Pr$_{5/16}$Ca$_{3/8}$MnO$_{3}$ will be presented and the driving mechanism of FM/CO phase separation will be discussed. Research sponsored by the U. S. Department of Energy under contract DE-AC05-00OR22725 with the Oak Ridge National Laboratory, managed by UT-Battelle, LLC