Growth-parameters-dependent magnetoresistance in pulsed-laser-deposited (La0.5 Pr0.2) Ba0.3 Mn O3 thin films

Abstract

Epitaxial thin films of (La0.5 Pr0.2) Ba0.3 Mn O3 were deposited on LaAl O3 single-crystal substrates using pulsed laser deposition (PLD) technique with different growth parameters. Structural, surface morphological, electrical, and magnetotransport measurements on these films revealed that unoptimized growth parameters during the deposition using the third harmonic of a Q -switched Nd: YAG laser yielded structurally inhomogeneous epitaxial films having a columnar morphology, while the optimized growth parameters using an excimer laser during the PLD resulted in homogeneous epitaxial films with a smooth morphology. Interestingly, at a temperature of 5 K, the films with unoptimized growth parameters showed a large high-field magnetoresistance (MR) of ∼90% while the films with optimized growth parameters showed a high-field MR of only ∼15%. It is contemplated that this exceptionally large MR in the unoptimized films might be due to the phase separation and coexistence of metallic and insulating phases. © 2005 American Institute of Physics.