Separation of Curie temperature and insulator-metal transition temperature in the La0.7Sr0.3MnO3 polycrystalline films and its effect on low field magnetoresistance

Abstract The polycrystalline La 0.7 Sr 0.3 MnO 3 films were deposited on SiO 2 /Si substrates by pulsed laser deposition (PLD), and the temperature gap between Curie temperature ( T C ) and insulator-metal transition temperature ( T IM ) was tuned successfully by the deposition temperature and its influence on the LFMR properties was investigated. The results showed that the T C was sensitive to the Mn 3+ /Mn 4+ ratios, whereas the T IM was sensitive to the microstructures in the LSMO films. The LFMR properties of the LSMO films were enhanced with increasing the Δ T values (Δ T  =  T C  −  T IM ). Our results provide an effective way to modulate the functional properties of LSMO films by modulating the temperature gap between T C and T IM .