Magneto-Transport Properties of $\hbox{La}_{0.7}\hbox{Ca}_{0.3-{\rm x}}\hbox{Sr}_{\rm x}\hbox{MnO}_{3}$ Thin Films Deposited by Pulsed Electron Deposition

We report the magneto-transport properties of La 0.7 Ca 0.3-x Sr x MnO 3 ( x =0 , 0.075, 0.1, 0.125, 0.15, 0.3) thin films on (100) LaAlO 3 substrates prepared by pulsed electron-beam deposition (PED). With increasing x from 0 to 0.3, both Curie temperature ( TC ) and metal-insulator transition temperature ( TMI ) of the films were increased from 206 and 212 K to 339 and 366 K, respectively. Except x =0.125 film, with increasing x , all other LCSMO films showed a tendency of gradual decrease in the maximum MR ratios ( MR MAX ) at increased maximum MR temperature ( T MAX, ) values. The film of x =0.125 exhibited extraordinary high MR MAX value of 16% at 306 K. After post-annealing in a pure oxygen atmosphere at 900 deg C, this film showed more enhanced MR MAX of 18% at 325 K.