PULSED-LASER DEPOSITION OF LA2 3CA1/3MNO3 FILMS AT LOW-OXYGEN PRESSURES/

Films deposited by pulsed laser ablation from La2/3Ca1/3MnO3 targets e xhibit a large variety of properties depending on the exact preparatio n conditions. The as-deposited films at high enough oxygen pressures P -O2, have transition temperatures (T-c) close to that of the target ma terial (265 K). At lower P-O2 the films can be made to have lower T-c' s but as P-O2 is decreased below a certain value, an insulating behavi or in all the temperature range is observed. X-ray diffraction pole-fi gure measurements of these insulating films indicate an extremely stra ined structure. By post annealing in oxygen these films are recrystall ised and a T-c of 265 K is restored. However the highest magnetoresist ance value of (rho(0)- rho(H))/rho (H)= 109000%, at H= 50 kOe, was obt ained for a film having a transition temperature of 135 K. (C) 1998 El sevier Science S.A. All rights reserved.