In this letter we use the replica trick together with a variational method in order to compute the effective conductivity tensor of a disordered binary composite in a static magnetic field. When only of the two components percolates, the effective magnetoresistivity ρxx(e) saturates for strong magnetic fields h as in a homogeneous material. When both components percolate, the effective magnetoresistivity displays an anomalous behaviour and scales like the magnetic field h. At the percolation threshold of one component (denoted by pc), the scaling exponent ν (ρxx(e)∼hν) is equal to 2/3 and there is a scaling behaviour with both h and p−pc (where p denotes the volume fraction). This indicates that there is a field-dependent correlation length at strong fields that is distinct from the percolation correlation length. In all cases the effective Hall constant RH saturates at strong fields.

Original languageEnglish
Pages (from-to)305-310
Number of pages6
JournalJournal de Physique (Paris), Lettres
Issue number4
StatePublished - 1 Aug 1994


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