Quasi-Random Resistor Network Model for Linear Magnetoresistance of Metal--Semiconductor Composite

A new model for the linear magentoresistance (MR) of the Ag_2+δSe and Ag_2+δ Te thin films is proposed. The thin film is considered as a metal--semiconductor composite and dispersed into an N×N quasi-random resistor network. The network is constructed from four-terminal resistors and the mobility of carries μ within the network has a quasi-random distribution, i.e. a Gaussian distribution with two constraint conditions. The model predicts that the MR increases with the increasing magnetic fields, and increases linearly at high field. Moreover, the MR decreases with the increasing temperatures. A good agreement between the theoretical MR and the available experimental data is found.