Preparation and colossal magnetoresistance in a trilayer La_(0.67)Sr_(0.33)MnO_3/La_(0.75)MnO_3/La_(0.67)Sr_(0.33)MnO_3 device by dc magnetron sputtering

摘要

Epitaxial trilayer films of La_(0.67)Sr_(0.33)MnO_3 (LSMO)/La_(0.75)MnO_3 (L0.75MO)/La_(0.67)Sr_(0.33)MnO_3 (LSMO) have been prepared on (001) oriented LaAlO_3 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/R_0) 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.