Magnetoresistivity effect in La0.67Sr0.33MnO3-delta/Pr0.7Ca0.3MnO3-delta/La0.67Sr0.33MnO3-delta trilayered films

The structure, magnetic and transport properties of high-quality La0.67Sr0. 33MnO3-delta/Pr0.7Ca0.3MnO3-delta/La0.67Sr0.33MnO3-delta (LPL) trilayered e pitaxial films have been studied systematically. It was found that there is a transition from spin cluster-glass phase to ferromagnetic phase in the L PL films, and the resistivity decreases and M-I transition temperature (T-p ) increases with the increase of middle-layered Pr0.7Ca0.3MnO3-delta (PCMO) thickness. It is interesting to notice that the maximum resistivity change Delta R/R-LPL(100 nm) is about -270% near 150 K, where Delta R = (R-LSMO-R -LPL(100 nm)). R-LSMO and R-LPL(100 nm) are the resistivities of La0.67Sr0. 33MnO3-delta (LSMO) and LPL (100 nm) films, respectively, in zero-magnetic field. These results imply that there may exist an intrainteraction between the LSMO and PCMO layers in the LPL films, and that the middle-layered PCM O may act as a role of intramagnetic field and induce the change of the den sity of state in the LSMO gap. Magnetoresistivity values of the LPL films i n a magnetic field of 0.75 T decrease with the increase of the thickness of middle-layered PCMO. [S0163-1829(99)13513-6].