Anomalous Hall effect in granular Fe/SiO2 films in the tunneling-conduction regime

It is established that the Hall effect in Fe/SiO2 nanocomposite films in th e activational tunneling conduction range is anomalous, i.e., the Hall resi stivity rho(h) is proportional to the magnetization and is due to the spin- orbit interaction. The parametric coupling of the Hall and longitudinal (rh o(xx)) resistances rho(h)proportional to rho(xx)(m) (with temperature as th e parameter) is characterized by a much lower value of the exponent m than in a uniform ferromagnetic metal. This circumstance is attributed to the ch aracteristic features of the Hall effect mechanism in the hopping regime - in our case, the interference of the amplitudes of tunneling transitions in a set of three granules. (C) 1999 American Institute of Physics. [S0021-36 40(99)00514-9].