Influence of crystallographic orientation on electronic phase separation in manganite thin films

Abstract

Thin film epitaxy is a powerful method to control the strain and crystallographic orientation of the thin films using epitaxial relationship with the substrate. For colossal magnetoresistive (CMR) manganites thin films, the strong correlation between spin, charge, orbital and lattice degrees of freedom make their physical properties depend sensitively on the choice of substrate. This is especially true when considering the fact that the physical behaviors of manganites are often governed by electronic phase separation (EPS) phenomena, whose physical origin is strongly tied to lattice strain distribution. While many studies have been conducted on the substrate lattice mismatch induced strain effect, research on the substrate crystallographic orientation effect on EPS has received less attention. In this work, using (La2/3Pr1/3)5/8Ca3/8MnO3 (LPCMO) films grown on SrTiO3 (STO) substrate as a protype system, we show that EPS and its associated physical properties are strongly affected by the substrate crystallographic orientations. Specifically, we observed a clear boost of ferromagnetism in (110)-oriented LPCMO thin films with elongated EPS domains. First principles calculations show that the magnetic phase transitions of LPCMO are dominantly influenced by the spin-lattice coupling.