Hopping anomalous Hall effect in Fe-SiO2 granular films

It was established that the Hall effect in nanocomposite Fe/SiO2 under conditions of tunnel-activated conductivity is anomalous, that is the Hall resistivity Q(H) is proportional to the magnetization and results from the spin-orbit interaction. As this takes place, the parametric relation Q(H) proportional to Q(xx)(m) between the Hall resistivity and the longitudinal (Q(xx)) one (parameter is temperature) is characterized by a significantly smaller exponent m than for a homogeneous ferromagnetic metal. By analogy with the hopping conductivity, this behaviour was related to features of the Hall effect mechanism in the hopping regime. In our case, it is the amplitude interference of tunnel transitions within three granule-sets.