Crystallinity and magnetoresistance in La1−xCaxMnO3 thin films

Abstract

The crystallinity of La1−xCaxMnO3 (LCMO) thin films can be controlled by preparing the films on substrates with different lattice parameters. Closely lattice matched LCMO thin films on LaAlO3 (LAO) substrates exhibit a high degree of crystallinity and have magnetoresistance (MR) and MR ratio [R(H=0 T)-R(H=6 T)]/R(H=6 T) that is sharply peaked in the vicinity of the metal-insulator transition temperature (TMI). Notably, films grown on LAO(011) have TMI shifted up in temperature ∼20 K higher than the same films on LAO(001) substrates. LCMO films on Al2O3 and Y-ZrO2, that are not as closely lattice matched, have a lower degree of crystallinity, less sharply peaked MR and a nearly constant MR ratio below TMI over a broad temperature range.