Hysteresis and interaction between the magnetic layers in spin valves

Spin valve characteristics have been investigated in the samples of glass /Ta(X Å)/NiFe(Y_f Å)/Cu(Z Å)/NiFe(Y _p Å)/FeMn(150 Å)/Ta(50 Å) with various X, Y _f, Y_p and Z values. The pinning field of FeMn increases and saturates X, Y_f and Y_p, followed by an improvement of (111) texturing of the NiFe/Cu/NiFe/FeMn layers. GMR vs. field curves in the easy magnetization direction were studied for various Cu thicknesses, Z. With decreasing Z, the coercivity of the free layer begins to decrease, followed by a reduction of the GMR effect which finally disappears. This change can be explained semi-quantitatively by theoretical analysis which assumes some dispersion in the direction of the pinning field