Spin-Polarized Tunnelling Magnetoresistance Effects in La0.833K0.167MnO3/SrTiO3 Polycrystalline Perovskite Manganites
WU Jian1,2, ZHANG Shi-Yuan1, HU Xiu-Kun1
1National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093
2Department of Mathematics and Physics, Hohai University, Nanjing 210098
Spin-Polarized Tunnelling Magnetoresistance Effects in La0.833K0.167MnO3/SrTiO3 Polycrystalline Perovskite Manganites
WU Jian1,2;ZHANG Shi-Yuan1;HU Xiu-Kun1
1National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093
2Department of Mathematics and Physics, Hohai University, Nanjing 210098
Abstract： A sample of La0.833K0.167MnO3-SrTiO3(LKMO/STO) is fabricated by the sol-gel method. The microstructure, magnetic and transportation properties have been studied. X-ray diffraction patterns indicate that the structure of LKMO/STO is a homogeneous solid solution phase. The resistivity of LKMO/STO shows the insulator behaviour, which is different from La0.833K0.167MnO3 (LKMO) whose resistivity shows metal--insulator transition with decreasing temperature. The low-field (mLa0.833K0.167MnO3/SrTiO0 H=0.02T) magnetoresistance decreases from 11% to 0.2% with the increasing temperature from 4K to 220K for the LKMO/STO sample. The magnitude of magnetoresistance in a strong field (La0.833K0.167MnO3/SrTiO0H=5.5T) almost increases linearly with decreasing temperature and reaches the maximum of 65% at the low temperature of 4.2K, which is much higher than that of LKMO (40%). The enhanced low-field magnetoresistance effects are quantitatively explained by the spin-polarized tunnelling at grain boundaries.
2005, Vol. 22 
