Electrical transport properties of topographically demorphed films of La 1-x Ba x MnO 3 grown on (00 l )-oriented LaAlO 3 substrate via spin-coating method

Herein, the crystal structure, valence, and electrical transport properties of La 1-x Ba x MnO 3 films were examined by preparing La 1-x Ba x MnO 3 films with varying Ba content ( x  = 0.22, 0.24, 0.26, 0.28) on LaAlO 3 substrates using the sol-gel spin coating technique. The La 1-x Ba x MnO 3 films prepared in the study exhibit topographically demorphed and non-dense characteristics in the microstructure, which is mainly caused by the Volmer-Weber growth mode of the films and the volatilization of organic matter during the sol-gel sintering process for films preparation. The increase of Ba doping leads to MnO 6 deformation, decrease in grain boundary scattering, increase in Mn 4+ ion content, and enhancement of both the double exchange mechanism and the Jahn-Teller effect. The four-probe results showed that the peak resistivity of the films decreased significantly with the increase in Ba 2+ doping, and the metal-insulator transition temperature ( T p ) shifted to higher temperatures. Peak temperature coefficient of resistivity ( TCR ) corresponding temperature ( T k ) increased from 283.05 K ( x  = 0.22) to 309.31 K ( x  = 0.28), which was consistent with the trend of T p ; the peak value of TCR decreased with the increase of Ba doping. When x  = 0.24, the T k of the La 1-x Ba x MnO 3 films reach room temperature (294.25 K) with TCR  = 9.01 % K −1. In conclusion, the electrical properties of La 1-x Ba x MnO 3 can be optimized by varying the amount of Ba doping to obtain La 1-x Ba x MnO 3 films with room-temperature T k and higher TCR values, providing reasonable data support and theoretical explanation for the Ba doping mechanism.