RECENT ADVANCES IN STRONG-FIELD MAGNETOTRANSPORT IN A COMPOSITE MEDIUM

Macroscopic inhomogeneities have a profound effect on electrical condu ctivity in the presence of a strong magnetic field B. One expression o f this is the appearance of a new physical length in the system, which increases with B and is unbounded. This length characterizes the extr a distortions of the local current density which are produced by the s trong Hall effect. In fractal clusters, different scaling behavior is found to occur at scales above and below this length. In random percol ating systems, the new length competes with the percolation correlatio n length for dominance over the critical behavior. The divergence of e ach of these lengths is associated with a different fixed point. In me tallic composites with a periodic microstructure, the new length is re sponsible for a strong anisotropy which appears in the magneto-resista nce, even when the rotational symmetry is simple cubic or simple squar e.