Preferred-orientation effects on the ferromagnetic properties of La _1-xSr_xMnO₃ films deposited on Si substrates

La1-x Srx MnO3 (LSMO) films of x∼0.1 with and without (100)-preferred orientation were fabricated on SiO2 Si substrates. A slight oxygen deficiency and high tensile stress were found in LSMO films. All the films exhibit a ferromagnetic transition at temperature (Tc) around 250 K and a metal-insulator transition at temperature (TM-I) much lower. However, a significant increase of saturated magnetization and a decrease of resistivity along with a significant raise of TM-I are observed in the film without (100)-preferred orientation. The change of ferromagnetic property is attributed to the alleviation of Jahn-Teller distortion induced by the thermal stress in films having different preferred orientations.