Tunneling magnetoresistance and Hall effect of granular ferromagnetic metals

It is shown that two circumstances must be taken into account in order to describe the tunneling magnetoresistance and Hall effect in granular ferromagnetic metals: 1) the size variance of the metallic granules and 2) the percolation character of the tunneling conductivity of the system, determining the optimal (temperature-dependent) size of the granules through which current transport occurs. This complicates the dependences of the magnetoresistance and Hall resistance of the system on its magnetization and temperature. Pis’ma Zh. éksp. Teor. Fiz. 69, No. 8, 579–584 (25 April 1999)