Nonsaturating magnetoresistance of inhomogeneous conductors: Comparison of experiment and simulation
Nonsaturating magnetoresistance of inhomogeneous conductors: Comparison of experiment and simulation
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DOI：
10.1103/physrevb.75.214203
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发表时间：
2007-06-01
影响因子：
3.7
通讯作者：
Rosenbaum, T. F.
中科院分区：
文献类型：
--
作者：
Hu, Jingshi;Parish, Meera M.;Rosenbaum, T. F.
银硫属化物提供了一个不完美的好处的突出例子。过量银的纳米线引起电流的畸变，产生线性和非饱和横向磁阻（MR）。与大的正MR相关联的是负纵向MR。纵向MR仅发生在三维极限中，从而允许确定由空间不均匀性设置的特征长度尺度。我们发现，这个基本的不均匀性长度可以高达10 μ m。在各种样品几何形状的电阻率张量的对角和非对角分量的系统测量显示出明确的证据，在理论模拟中假设的扭曲的电流路径。我们使用一个随机电阻网络模型来拟合线性MR，并将其从二维扩展到三维来描述第三（厚度）维的电流失真。当直接比较Ag 2 +/-δ Se和Ag 2 +/-δ Te的实验，在高达55 T的磁场中，该模型确定了由于宏观不均匀性的电导率波动作为基本的物理机制。它还合理地定量解释了实验中观察到的电阻率张量的各个分量。
The silver chalcogenides provide a striking example of the benefits of imperfection. Nanothreads of excess silver cause distortions in the current flow that yield a linear and nonsaturating transverse magnetoresistance (MR). Associated with the large and positive MR is a negative longitudinal MR. The longitudinal MR only occurs in the three-dimensional limit and thereby permits the determination of a characteristic length scale set by the spatial inhomogeneity. We find that this fundamental inhomogeneity length can be as large as 10 mu m. Systematic measurements of the diagonal and off-diagonal components of the resistivity tensor in various sample geometries show clear evidence of the distorted current paths posited in theoretical simulations. We use a random-resistor network model to fit the linear MR, and expand it from two to three dimensions to depict current distortions in the third (thickness) dimension. When compared directly to experiments on Ag2 +/-delta Se and Ag2 +/-delta Te, in magnetic fields up to 55 T, the model identifies conductivity fluctuations due to macroscopic inhomogeneities as the underlying physical mechanism. It also accounts reasonably quantitatively for the various components of the resistivity tensor observed in the experiments.