Influence of lattice strain on phase separation and percolative behaviors in La0.325Pr0.3Ca0.375MnO3 thin films

The (La_1-yPr_y)_1-xCa_xMnO₃ systems has been extensively studied in recent years as a typical electronic phase separation(PS) system. As well known, the average radius of A sites in the ABO₃ structure plays a key role in determining the band (W) and electronic characteristics of the perovskite manganites. Uehara et al has found that the chemical replacement of Pr for La (Pr is smaller than La) could reduce the W, as a result, the ferromagnetic metallic (FM) phase transforms into the charge/orbital ordering (COO) partially. Therefore, the coexistence and competition of the FM metallic phase with the COO insulating phase emerges upon Pr doping. On the other hand, the strain exerted by the lattice mismatch between the substrate and bulk also plays an important role in controlling the magnetic and transport properties of films, which can influence the balance of free energy between the coexistent COO and FM phases by adjusting the strength of the double exchange interaction and the Jahn-Teller (JT) electron-lattice coupling. Here, we report the strain effects on the phase separation and the competition between COO and FM phases in La_0.325Pr_0.3Ca_0.375MnO₃ (LPCMO) thin films.