Preparation and colossal magnetoresistance in a trilayer La0.67Sr0.33MnO3/La0.75MnO3/La0.67Sr0.33MnO3 device by dc magnetron sputtering

Epitaxial trilayer films of La0.67Sr0.33MnO3 (LSMO)/La0.75MnO3 (L0.75MO)/La0.67Sr0.33MnO3 (LSMO) have been prepared on (0 0 1) oriented LaAlO3 substrates by dc magnetron sputtering. The structure and MR are studied. All as-deposited trilayer films exhibit a semiconductor to metal transition at temperature ranging from 116 to 185 K. The MR is also shown to be dependent on the thickness of the middle oxide layer. A maximum MR value of 32% (ΔR/R0) has been obtained at 132 K under 0.4 T magnetic field for a LSMO (300 nm)/L0.75MO (70 nm)/LSMO (300 nm) trilayer film. The MR of trilayer film prefers to that of both LSMO and L0.75MO single layer films.