A line current method, a theory of measurement of anisotropic resistivity, and a really exact universal correction function

Resistivity, especially anisotropic resistivity, is an interesting property in many materials. In this paper a line current (LC) method is presented. For large crystal samples, there is no difficulty in obtaining all components of their resistivity tensors by this LC method. However, it is difficult to measure the component in the vertical direction of thin films and one must make three independent measurements. For a given thin film, for the LC method, one can have only two independent designs for the probe configurations. In this paper, a theory for measuring the resistivity of anisotropic crystals based on two films with two orientations is proposed, which can be applied to films and bulk of high-T_c superconductors or semiconductors. The insensitivity of certain components in the measurement is solved through the arrangement of probes on the crystal. The method can be widely applied, and an exact universal correction function in practice, expressed by composite elementary functions, is obtained.