Crossover of magnetotransport process toward spin-polarized tunneling in manganite thin films

摘要

We report on the magnetoresistive features of well-characterized polycrystalline manganite thin films as a function of film thickness. A crossover of the magnetization process from domain wall displacement to magnetic rotation of each grain is observed around a thickness of 25 nm, accompanied with the maximum of the coercivity. The thickness dependence of the electrical resistivity clearly distinguishes the transport mechanism at 25 nm, below which the magnetoresistance can be well scaled by similar to(M/M-S)(2), using the magnetization M and the saturation magnetization M-S. Spin-polarized tunneling transport between adjacent grains provides a comprehensive picture for the magnetotransport data. (C) 2002 American Institute of Physics. References: 16