Effects of surface/interface morphology on giant magnetoresistance and magnetic field sensitivity of NiO-based spin-valves

The effects of surface/interface morphology on the giant magnetoresistance (GMR) and magnetic field sensitivity (MFS) of NiFe/Co/Cu/Co/NiFe/NiO/Si and Co/Cu/Co/NiO/Si bottom spin-valve films were studied. The NiO-based spin valves were fabricated on NiO films with different surface roughnesses, A GMR of 4.02% and a MFS of 0.83%/Oe were obtained from the spin-valves with a smoother surface/interface. A GMR of 5.46% and a MFS of 0.22%/Oe in low field and a GMR of 6.26% and a MFS of 0.16%/Oe in high field were obtained from the spin-valve films with a rougher surface/interface. It was found that the smoother the surface of the spin-valve films, the smaller the GMR hut the larger the MFS. On the other hand, the rougher the surface of the spin-valve films, the larger the GMR but the smaller the MFS. The mechanism for surface/interface morphology affecting the GMR and MFS is also explored.