科研之友
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摘要
Based on a simple model of spin-dependent scattering, an improved microscopic approach is proposed to describe the magnetoresistance in granular magnetic systems. The feature is the explicit account of correlated scattering of conduction electrons between granule pairs and of transitions between spin-up and spin-down states. Besides the usual term, proportional to the square of the magnetization, an extra contribution to the magnetoresistance ratio Delta rho/rho is obtained, proportional to the correlator [cos theta(12)], where theta(12) is the angle between magnetic moments of neighbor granules. The field dependence of Delta rho/rho, together with its dependencies on granule concentration, granule mean size, granule size distribution, temperature and annealing effects, are considered, leading to a reasonable agreement with available experimental data. [S0163-1829(98)02925-7].
- 出版日期1998-7-1
