半导体-金属复合结构中的异常磁电阻效应分析

Analysis of extraordinary magnetoresistance effects in semiconductor-metal hybrid structures

从电磁方程的解析解出发,分析高对称性van der Pauw disk装置的异常磁电阻效应,重点研究该体系的几何非均匀性与物理非均匀性对整体磁电阻效应的影响.通过定义三个非均匀参数表征体系的非均匀性,给出该装置中电磁输运性质随非均匀系数的变化.计算结果表明,体系的磁电阻比值在一定的几何非均匀结构下达到最优化,整个装置在磁场下呈现出良好的开关效应.同时,材料在迁移率和电阻率上的非均匀性对异常磁电阻效应产生明显影响.特别地,组分电阻率的差别导致异常磁电阻效应出现符号翻转.

Based on the analytic solutions of basic electromagnetic equations, the extraordinary magnetoresistance effects are calculated in van der Pauw disk structures, especially the effects of inhomogeneity on the magnetotransport properties. Three parameters have been defined to describe the inhomogeneous systems. The dependence of magneto- resistance on these parameters is calculated. The results show that the extraordinary magnetoresistance reaches its maximum in an optimal geometry so that the whole structure behaves as switches at applied fields. The calculated magnetoresisance also depends on the mobility and conductivity inhomogeneity. In particular, the mismatch between the component conductivities leads to the sign inverse of magnetoresistance.