The colossal magnetoresistance in wide temperature region of Pr0.7Sr0.3MnO3 film on Pb(Mg1/3Nb2/3)0.7Ti0.3O3 substrate

Abstract

The magnetotransport and colossal magnetoresistance (MR) in wide temperature region of Pr0.7Sr0.3MnO3 film grown on Pb(Mg1/3Nb2/3)0.7Ti0.3O3 (PMNPT) substrate have been studied in detail. The X-ray diffraction (XRD) measurement shows that the Pr0.7Sr0.3MnO3/PMNPT film reveal the out-of-plane single orientation and the atomic force microscopy (AFM) measurement indicates that the surface of the sample is very smooth. Moreover, some obvious interference peaks of the film and the full width at half maximum (FWHM) of 0.28° for (002) diffraction peak are observed in the XRD pattern. These phenomena suggest the high quality of the thin film. The magnetotransport and the MR effects associated to both the double exchange (DE) interaction and the spin polarized tunneling have been investigated using the temperature dependence of resistivity (ρ-T), the temperature dependence of MR (MR-T) and the magnetic filed dependence of resistivity (ρ-H). The ρ is increased gradually with decreasing the temperature, but a metal-insulator (MI) transition appears in the ρ-T curves. The MI temperature (TMI) is increased with increasing the applied field. The MR values (MR = [ρ-ρ0/ρ0]×100%) reach 25.2%, 47.8%, 69.4% and 77.8% at the applied fields of 1 , 2 , 4 and 6 T, respectively. At around TMI, the ρ changes significantly with the applied field. This indicates a colossal MR at around TMI, which can be explained by the DE mechanism. Compared with other works on Pr0.7Sr0.3MnO3, the Pr0.7Sr0.3MnO3 film on PMNPT exhibits the colossal MR in wide temperature region. Remarkably, there is two types of MR mechanisms in this work, i.e., the MR effect at around TMI caused by the DE interaction and the MR effect at low temperature (below TMI) resulted from the spin polarized tunneling, which lead to the wide temperature region of the MR.