Structural and microscopic analyses of (alpha-Fe2O3/Co(NiFe)/Cu/Co(NiFe) bottom GMR spin valves

The structural and microscopic analyses of Si/alpha -Fe2O3/Co(NiFe)/Cu/Co(N iFe) bottom GMR spin valves with Co or NiFe free and pinned layers were per formed from the point of view of material characteristics. The input sputte ring power, substrate bias, and sputtering power source (RF; or DC magnetro n) were used as experimental variables. It was confirmed that the crystal s tructure of alpha -Fe2O3 related to the anti-ferromagnetic crystalline anis otropy, the surface roughness associated with coupling field(bias field) be tween the free and the pinned layers through the nonmagnetic Cu layer, and the inter-diffusion were crucial factors in determining the GMR performance of Si/alpha -Fe2O3/Co(NiFe)/Cu/Co(NiFe). The increase of Ni-Cu intermixing region due to the Cu inter-diffusion was shown to be a much more dominant factor as compared to the interfacial surface roughness in reduction of GMR ratio in alpha -Fe2O3 bottom spin valve.