Giant Hall effect in granular Fe–SiO2 film

Abstract

We have studied the resistivity, magnetoresistivity, and Hall resistivity for a few Fex(SiO2)1−x granular films with Fe volume fraction x near the metal insulator transition threshold xc. Both the ordinary Hall coefficient R0 and the saturated extraordinary Hall resistivity ρxys were found to be enhanced by a factor of 104 when x approaches xc. The largest measurable R0 and ρxys at room temperature are about 10−3 μΩ cm/G and 250 μΩ cm, respectively. By comparing with the Ni-rich NiFe–SiO2 system [A. B. Pakhomov, X. Yan, and B. Zhao, Appl. Phys. Lett. 67, 3497 (1995)], we found that the correlation between giant Hall effect and the resistivity with a −log T-like dependence is independent of the sign of the carrier. The feasibility of using such a system as a magnetic-field sensor is discussed.