Pulsed laser deposition of La2/3Ca1/3MnO3 films at low oxygen pressures

Films deposited by pulsed laser ablation from La2/3Ca1/3MnO3 targets exhibit a large variety of properties depending on the exact preparation conditions. The as-deposited films at high enough oxygen pressures PO2, have transition temperatures (Tc) close to that of the target material (265 K). At lower PO2 the films can be made to have lower Tcʹs but as PO2 is decreased below a certain value, an insulating behavior in all the temperature range is observed. X-ray diffraction pole-figure measurements of these insulating films indicate an extremely strained structure. By post annealing in oxygen these films are recrystallised and a Tc of 265 K is restored. However the highest magnetoresistance value of (ρ(0)−ρ(H))/ρ(H)=109 000%, at H=50 kOe, was obtained for a film having a transition temperature of 135 K.