Electronic Phase Separation in Manganite Superlattices

For manganite superlattices, it has been known that the interfacial effect can give rise to strikingly new physical properties. In this work, we investigate the influence of the superlattice periodicity on electronic phase separation (EPS) phenomena in manganites. We combine magnetic force microscopy (MFM) studies and model calculations to study the n-dependence of EPS of the (La_5/8Ca_3/8MnO₃)_2n/(Pr_5/8Ca_3/8MnO₃)_n superlattices, and found that the EPS length scale depends sensitively on n. Magnetic and transport measurements also indicate that the physical properties change non-monotonically with increasing n, reaching a minimum at n ~ 6 or 7 for both the Curie temperature and the metal-insulator transition temperature. With increasing n over 7, the physical properties of the superlattice are governed by those of the La_5/8Ca_3/8MnO₃ and the Pr_5/8Ca_3/8MnO₃ layers.