Magnetic properties of La–Sr–Mn–O/Si thin film as a function of RF magnetron power and O2 partial pressure

Abstract Polycrystalline perovskite compound sputtering target La 0.67 Sr 0.33 MnO 3 has been prepared by a conventional ceramic method. La–Sr–Mn–O/Si thin films have been produced under various applied RF sputtering power and oxygen partial pressure at 700°C. Deposited thin films were annealed for 1 h at 800°C in O 2 atmosphere. Structures, magnetic properties and compositions of the La–Sr–Mn–O films have been studied with X-ray diffraction, Rutherford back-scattering spectroscopy (RBS), atomic force microscopy, scanning electron microscopy and vibrating sample magnetometer. Crystalline La–Sr–Mn–O thin films was perovskite monoclinic. In the case of RF-power 2.46 W/cm 2 and P O 2 =20%, La 0.85 Sr 0.15 MnO 3 films have lattice parameters a 0 =5.489 A, b 0 =5.517 A, c 0 =7.769 A and β =89.07°. The thickness of La 0.85 Sr 0.15 MnO 3 film was found to be 900±50 A by α-step and RBS measurement. The coercive force and the saturation magnetization of the La 0.85 Sr 0.15 MnO 3 film at room temperature was H C∥ =5 Oe and M S∥ =235 emu/cm 2 with applied field 5 kOe. The temperature dependence of the resistance under zero and 15 kOe applied fields shows that a semiconductor–metal transition, T SC–M , occurs at 240 K. The relative magnetoresistance, MR, is about 9.6%.