Recent advances in strong field magneto-transport in a composite medium

Macroscopic inhomogeneities have a profound effect on electrical conductivity in the presence of a strong magnetic field B. One expression of this is the appearance of a new physical length in the system, which increases with B and is unbounded. This length characterizes the extra distortions of the local current density which are produced by the strong Hall effect. In fractal clusters, different scaling behavior is found to occur at scales above and below this length. In random percolating systems, the new length competes with the percolation correlation length for dominance over the critical behavior. The divergence of each of these lengths is associated with a different fixed point. In metallic composites with a periodic microstructure, the new length is responsible for a strong anisotropy which appears in the magneto-resistance, even when the rotational symmetry is simple cubic or simple square.