Giant Hall effect in nonmagnetic Mo/SnO2 granular films

Abstract

We have measured the resistivities and Hall coefficients, R-H, of a series of nonmagnetic Mo-x(SnO2)(1-x) nanogranular films with the Mo volume fraction x ranging from similar to 0.29 to 1. We found that the magnitude of R-H(2 K) largely increased by a factor of similar to 800 as x was reduced from similar to 0.8 to similar or equal to 0.36. Then, it slightly decreased with a further decrease in x down to similar or equal to 0.32, which was determined to be the classical percolation threshold, x(c), from the resistivity dependence on x. This nearly 3 orders of magnitude enhancement in R-H at a metal volume fraction x > x(c) is explained in terms of the recent theoretical concept of the local quantum-interference effect induced giant Hall effect in granular systems.