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We have determined the dependence of the exchange coupling on both the thickness of the antiferromagnetic (AF) layer (tAF) and that of the ferromagnetic (FM) layer (tFM) in a Fe50Mn50/permalloy bilayer, where the thickness of the FeMn layer varies from 0.5 to 32 nm with a fixed permalloy layer of 30 nm, and that of the permalloy layer varies from 3.5 to 45 nm with the uniform FeMn layer fixed at 10 nm. For tAF>3 nm, the exchange field Hex varies as 1/tAF0.3 at both 80 and 300 K, whereas the coercivity does not vary with tAF. The dependence of Hex on tFM displays a behaviour varying as 1/tFM0.9, and HC a behaviour varying as 1/tFM1.7 which is close to the theoretical prediction based on a random field at the interface of a FM/AF bilayer.

A series of NiO(110 A)/FeNi(tF A)/Cu(24 A)/FeNi(tF A) spin-valve-structure samples were fabricated using ion beam sputtering. The exchange bias HE of the pinned FeNi layer increases as the FeNi thickness tF decreases. For tF

A series of (Co0.35Fe0.65)x(Al2O3)(1-x) (volume fraction) nanogranular films was fabricated using magnetron sputtering. The Hall effect of the films increases as the volume fraction of Co0.35Fe0.65 decreases near percolation. The saturated Hall resistivity of (Co0.35Fe0.65)0.43(Al2O3)0.57 is about 5.5 µΩ cm at room temperature. This suggests that the giant Hall effect (GHE) may be due to the percolation phenomenon. The correlation of the Hall effect and tunnelling magnetoresistance (TMR) with the alloy volume fraction is discussed.