Annealing effect on magnetic characteristics on (La,Sr)MnO sub(3) sputtered films

A perovskite type of (La,Sr)MnO sub(3) films were deposited on SiO sub(2)/Si substrates with amorphous surface by using the facing targets sputtering apparatus. Although the film as-deposited at P sub(O(2)) of 0.3 mTorr was not fully crystallized and MR ratio was as small as 0.03% at the applied field of 5 kOe, it increased up to 2.5% for the film post-annealed at 850 degree C in air for 10 min. The partial O sub(2) pressure P sub(O(2)) strongly affected their crystallinity as well as the Mn content C sub(Mn). The film as-deposited at P sub(O(2)) of 0.04 mTorr was composed of crystallites with excellent (100) orientation at relatively low substrate temperature T sub(s) up to 500 degree C and the large MR ratio of 3.8% was attained even at room-temperature measurement. Since this MR response exhibits excellent linearity, these LSMO films seem to be applied for magnetic sensor devices. It is clarified that annealing process in preparation of LSMO film is effective to increase the MR ratio of the film with insufficient crystallinity, and is not effective for the fully crystallized film.