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

The polycrystalline La0.7Sr0.3MnO3 films were deposited on SiO2/Si substrates by pulsed laser deposition (PLD), and the temperature gap between Curie temperature (TC) and insulator-metal transition temperature (TIM) was tuned successfully by the deposition temperature and its influence on the LFMR properties was investigated. The results showed that the TC was sensitive to the Mn3+/Mn4+ ratios, whereas the TIM was sensitive to the microstructures in the LSMO films. The LFMR properties of the LSMO films were enhanced with increasing the ΔT values (ΔT = TC − TIM). Our results provide an effective way to modulate the functional properties of LSMO films by modulating the temperature gap between TC and TIM.