Defects induced huge magnetoresistance in epitaxial La1-xSrxMnO3 thin films deposited by magnetic sputtering

In this work, epitaxial La1-xSrxMnO3 (LSMO) films were fabricated on SrTiO3 substrates at temperatures (T-s) ranging from 550 to 750 degrees C by RF magnetron sputtering. Significant T-s-dependent structural, magnetic, and magnetotransport properties were observed. The LSMO (T-s = 750 degrees C) film exhibits the colossal magnetoresistance (CMR) of -47% under the magnetic field (H) of 5 T. In contrast, the LSMO (T-s = 650 degrees C) film demonstrates a huge magnetoresistance (MR) of -98% (H = 5 T) around the metal-insulator transition temperature and -59% at 5 K. The spin-glass-like behaviors indicate that the defects, particularly the oxygen vacancies, in the epitaxial LSMO (T-s = 650 degrees C) films destroy the double exchange. The huge MR is related to the defect modulated magnetic structures and spin-dependent magnetotransport properties. Our work helps to understand the physical mechanism of the CMR and provides a way for tuning the magnetotransport properties of the perovskite films.