GIANT MAGNETORESISTANCE EFFECT IN LA0.8SR0.2MNO3 THIN-FILMS

The resistivity and magnetoresistivity behavior of highly oriented La0 .8Sr0.2MnO3 thin films have been studied in the temperature range 4.2 K less than or equal to T less than or equal to 300 K, in magnetic fie lds up to 4.5 T. The films exhibit a temperature-dependent giant magne toresistance (GMR) effect, with a maximum GMR of the order of similar to 60% in a field of 4.5 T, at 210 K. The temperature dependence of th e magnetization shows that the films are ferromagnetic below similar t o 200 K. The peak in GMR and zero-field resistivity is observed to lie near the magnetic transition temperature. Our results show that the f unctional dependence of the magnetoresistivity on the field H, changes from linear at 4.2 K to root H at 210 K. Above the Curie temperature, on the other hand, it shows a H-2 dependence. The resistivity, magnet oresistivity, and magnetization behavior of the present films exhibit a strong correlation as seen through their temperature dependences.